Note: Descriptions are shown in the official language in which they were submitted.
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BELOXEPIN, ITS ENANTIOMERS, AND ANALOGS THEREOF
FOR THE TREATMENT OF PAIN
1. CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C. 1.119(e) to
provisional application
No. 61/029,913 filed February 19, 2008, provisional application No. 61/029,915
filed
February 19, 2008, provisional application No. 61/029,916 filed February 19,
2008, and
provisional application No. 61/050,921 filed May 6, 2008, the disclosures of
which are
incorporated herein by reference in their entireties.
2. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0002] None.
3. PARTIES TO A JOINT RESEARCH AGREEMENT
[0003] None.
4. REFERENCE TO SEQUENCE LISTING, TABLE OR COMPUTER
PROGRAM
[0004] None.
5. BACKGROUND
[0005] Acute and chronic pain of both nociceptive and non-nociceptive origin
are disabling
conditions that affect significant numbers of individuals. Pain is frequently
characterized by
increased sensitivity to normally non-noxious stimuli (allodynia) and/or
painful stimuli
(hyperalgesia). Although antidepressants such as norepinephrine and serotonin
(5HT)
reuptake inhibitors have been used as a first-line therapy for treating
certain types of pain, for
example, pain associated with diabetic neuropathy, postherpetic neuralgia,
fibromyalgia,
irritable bowel syndrome and interstitial cystitis, none of these therapies
has proven to be
universally effective. Despite the number of therapies available, significant
numbers of
individuals still suffer debilitating pain on a daily basis. Accordingly,
there is a need in the
art for additional compounds and regimens useful for treating pain, whether
acute or chronic,
or due to nociceptive or non-nociceptive origin.
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6. SUMMARY
[0006] Racemic ( )-beloxepin, also known as "Org-4428" and "cis-1,2,3,4,4a,13b-
hexahydro-2,10-dimethyldiben-[2,3:6,7]oxepino [4,5c]pyridine-4a-ol]," is a
tetracyclic
compound that underwent clinical evaluation as a potential antidepressant in
the late 1990s.
According to published reports, beloxepin is a highly specific inhibitor of
noradrenaline
reuptake in synaptosomes from rat and primate brain in in vitro assays, having
greater than
100-fold less affinity for other monoamine carriers (i.e., serotonin and
dopamine
transporters), and no or very weak affinity for noradrenergic, histaminergic
and cholinergic
receptors (Sperling & Demling, 1997, Drugs of Today 33(2):95-102). It is also
reported to
have modest affinity for the 5HT2c receptor (Claghorn & Lesem, 1996, Progress
Drug Res
46:243-262).
[0007] In preclinical studies with animal models of depression, beloxepin was
noted to
exhibit antidepressant properties by offsetting acquired immobility behavior,
reserpine-
induced hypothermia, and conditioned avoidance behavior. In these tests,
beloxepin did not
cause sedation, motor impairment or other untoward side effects. Its profile
on EEG-defined
sleep/wake behavior is compatible with that of a nonsedative antidepressant
with sleep-
improving properties (Sperling & Demling, 1997, supra). Results of sleep
studies in human
volunteers have shown that beloxepin (25-400 mg) dose-dependently prolonged
REM
latency, both acutely and sub-chronically, and decreased total duration of
nocturnal REM
sleep as recorded by EEG (Van Bemmel et at., 1999, Neuropsychobiology
40(2):107-114).
No sedation or other side effects were observed. Based on these studies, it
was concluded
that beloxepin may reduce sleep continuity in depressed patients and may
improve the depth
of sleep.
[0008] In a single-dose safety study, beloxepin displayed linear kinetics over
a broad range,
with a dose-independent tmax of one to four hours and tj12 of 11 to 15 hr
following doses of 10
to 500 mg. Steady-state pharmacokinetic parameters obtained in healthy normal
subjects,
who participated in a multiple rising-dose safety and tolerance study, showed
that at doses of
50 to 800 mg, tmax was 1.17 hr and tj12 varied from 12 to 14 hr. No important
adverse effects
were observed in healthy volunteers who received up to 800 mg/day of
beloxepin. In a phase
IIA study in patients hospitalized for depression, 2/3 of patients had a
moderate to good
response, based on HAMD score reduction (Claghorn & Lesem, 1996, supra).
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[0009] In subsequent clinical trials, beloxepin exhibited insufficient
efficacy for the treatment
of major depression. Consequently further development of beloxepin was stopped
(Paanakker et at., 1998, J. Pharm. Biomed. Anal. 16(6):981-989).
[0010] As will be discussed further herein, it has been surprisingly
discovered by the present
inventors that beloxepin is not a selective inhibitor of the norepinephrine
transporter
("NET"), as reported in the literature. To the contrary, affinity testing with
over 125
receptors, channels and transporters indicates that beloxepin binds with only
modest affinity
to the NET (Ki = 700 nM), and also binds with modest affinity to the 5HT2A,
5HTzB and
5HT2c receptors (Ki = 440 nM, 1000 nM and 830 nM, respectively). In functional
assays,
beloxepin exhibited weak inhibition of norepinephrine reuptake (IC50 = 130 nM)
and
antagonist activity at the 5HT2A, 5HTzB and 5HT2c receptors (IC5os of 5200 nM,
>10,000 nM
and >10,000 nM, respectively). Moreover, beloxepin exhibited only marginal
affinity for the
serotonin (27% inhibition at 10 M in a competition assay) and dopamine (16%
inhibition at
M in a competition assay) transporters. Thus, it was surprisingly discovered
that
beloxepin, rather than being a selective NRI as reported in the literature, is
a dual NET
inhibitor/5HT2A,2B,2c antagonist.
[0011] Historically, antidepressants including those that inhibit reuptake of
NE (NRI5) and/or
5HT (SRIs) have been used as a first-line therapy for treating both acute and
chronic pain that
is either nociceptive or non-nociceptive in origin, for example, neuropathy,
post-herpetic
neuralgia (PHN), pain associated with fibromyalgia, pain associated with
irritable bowel
syndrome and interstitial cystitis (Sindrup and Jensen, 1999, Pain 83(3):389-
400; Collins et
at., 2000, J. Pain & Symptom Management 20(6):449-458; Crowell et at., 2004,
Current
Opin. Invest. Drugs 5(7):736-742). A recent study systematically evaluated the
relative
activity at the NE and/or 5HT transporter required for maximal efficacy in
rodent models of
pain (Leventhal et at., 2007, J. Pharmacol. Exper. Ther. 320(3):1178-1185).
The effects
observed replicate those observed clinically for treating neuropathic pain
conditions.
Namely, compounds with greater affinity for the NE transporter are more
effective at treating
pain, and compounds with greater affinity for the 5HT transporters have
limited efficacy (see,
e.g., Max et at., 1992; N. Engl. J. Med. 326(19):1250-1256; Collins et at.,
2000, supra).
Indeed, in a double-blind, placebo-controlled head-to-head study comparing the
tetracyclic
NRI maprotiline and the SRI paroxetine, reduction in pain intensity was
significantly greater
for study completers randomized to maprotiline (45%) as compared to paroxetine
(26%) or
placebo (27%) (Atkinson et at., 1999, Pain 83(2):137-145).
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[0012] Given its weak affinity for the NET and its weak, albeit selective,
inhibition of NE
reuptake, beloxepin would not be expected to be effective in treating pain.
Surprisingly, the
present inventors have discovered that not only is beloxepin extremely
effective in rodent
models of various different pain syndromes, its antiallodynic activity is
superior to that of
known NRI compounds (e.g., reboxetine), dual NRI/SRI compounds (e.g.,
duloxetine) and
tricyclic antidepressants (e.g., amitriptyline) currently used to treat pain
when dosed at the
same concentrations via IP administration.
[0013] Indeed, the magnitude of tactile allodynia observed for beloxepin in
the L5 SNL
rodent model of pain at 30 min post treatment is amongst the highest observed
by the
inventors in this model for drugs administered IP. Also see FIG. 11 and
Example 12,
presenting a comparison of the antiallodynic effects observed upon
administration beloxepin,
duloxetine, and esreboxitine using the rat L5 SNL model system.
[0014] As demonstrated in FIG. 3, beloxepin produced an observed mean
threshold of
approximately 15 g - nearly 5 times greater - under the same experimental
conditions than
reboxetine. With reference to FIG. 2, beloxepin produced a tactile
antiallodynic effect that
was 852% greater than that observed with vehicle-treated controls, and nearly
100% of that
observed with sham-operated animals.
[0015] Beloxepin also exhibited extremely robust activity in rodent models of
acute
nociceptive pain (FIGs. 6A and 6B), inflammatory pain (FIG. 7 and FIG. 9),
neuropathic pain
(FIG. 10 and Example 12), post-operative incisional pain (FIG. 12, FIG. 13,
FIG. 14, and
Example 13), and visceral pain (FIG. 8). For example, with reference to FIGS.
6A and 6B,
beloxepin exhibited anti-nociceptive activity almost equivalent to that of 3
mg/kg morphine.
With reference to FIG. 7, beloxepin exhibited nearly complete reversal of
hyperalgesia in rats
treated with Freund's Complete Adjuvant (FCA), and with reference to FIG. 8,
beloxepin
inhibited acetic acid-induced writhing in mice a dose-dependent fashion.
[0016] As noted above, beloxepin, i.e. ( )-beloxepin, is a racemic mixture of
two
enantiomers. The chemical structure of beloxepin is illustrated below:
N
HO H
0
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[0017] The OH and H substituents attached to the carbon atoms marked with
asterisks are in
the cis configuration with respect to one another. These carbon atoms are
chiral. As a
consequence, beloxepin is a racemic mixture of two cis enantiomers, a (+)
enantiomer and a
(-) enantiomer. The absolute configurations about the chiral carbons of the
(+) and (-)
enantiomers are unknown.
[0018] The biological activities of the (+) and (-) enantiomers of beloxepin
have not been
reported in the art. Studies carried out with these enantiomers by the present
inventors
reveals that they have distinct biological activities. Affinity and inhibitory
data at the NET
and 5HT2A, 5HT2B and 5HT2c receptors for these enantiomers, as well as the
data for racemic
( )-beloxepin are summarized in Table 1, below:
Table 1
Affinity and Activity of and (-)-beloxepin Data for Various Transporters and
Receptors
NET 5HT2A 5HT2B 5HT21
Ka, nM IC50, nM Ka, nM IC50, nM Ka, nM IC50, nM Ka, nM IC50, nM
(f) 700 130 440 5200 1000 >10,000 830 >10,000
antagonist antagonist antagonist
O 390 120 >10,000 nd >10,000 nd >10,000 nd
(+) 2920 1200 97 1600 170 690 84 7200
antagonist antagonist antagonist
nd = not determined
[0019] The (-) enantiomer binds with approximately 8-fold higher affinity at
the NET than
the (+) enantiomer, while being devoid of any significant affinity at the
5HT2A, 5HT2B and
5HT2c receptors. In stark contrast, the (+) enantiomer, which binds the NET
with only weak
affinity, displayed high affinity and antagonist activity at the 5HT2A, 5HT2B
and 5HT2c
receptors. These data reveal that each of the dual biological activities
discovered by the
present inventors for beloxepin are contributed almost exclusively by a single
enantiomer:
the NRI activity by the (-) enantiomer, and the 5HT2A,2B,2c antagonist
activity by the (+)
enantiomer. Thus, the present inventors have surprisingly discovered that
beloxepin, rather
than being a single compound with a single activity, is really three different
compounds with
three distinct biological activities: (i) racemic ( )-beloxepin, a dual
NRI/5HT2A,2B,2c
antagonist; (ii) (+)-beloxepin, a 5HT2A,2B,2c antagonist; and (iii) (-)-
beloxepin, an NRI. All of
these biological activities are known to correlate with therapeutic uses.
[0020] Accordingly, in one aspect, the present disclosure provides
compositions comprising
(-)-beloxepin and optionally one or more acceptable carriers, excipients or
diluents. The
(-)-beloxepin may be present in the composition as a non-racemic mixture
enriched in the
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(-) enantiomer. In some embodiments, the (-)-beloxepin is substantially
enantiomerically
pure (-)-beloxepin. In some embodiments, the (-)-beloxepin is enantiomerically
pure.
[0021] The (-)-beloxepin can be present in the composition in the form of the
free base, or in
the form of a salt. In some embodiments, the (-)-beloxepin is present in the
form of a
pharmaceutically acceptable acid addition salt.
[0022] The (-)-beloxepin composition can be used in vitro or in vivo, as will
be described in
more detail below. When used in vivo, the composition can be formulated for
administration
to animals in veterinary contexts, or for administration to humans via
virtually any route or
mode of administration, including but not limited to, oral, topical, ocular,
buccal, systemic,
nasal, injection, transdermal, rectal, vaginal, inhalation or insufflation. In
some
embodiments, the composition is formulated for oral administration, for
example, to humans.
[0023] Both selective and non-selective NRI compounds have proven effective in
the
treatment of a variety of diseases and disorders. It is expected that all of
these diseases and
disorders will likewise respond to treatment with (-)-beloxepin. Thus, in
another aspect, the
present disclosure provides methods of treating diseases and disorders
responsive to
treatment with NRI compounds. The methods generally comprise administering to
a
mammal, including a human, suffering from a disease or indication responsive
to treatment
with an NRI compound an amount of a (-)-beloxepin composition described herein
effective
to treat the disease or disorder. In some embodiments, the (-)-beloxepin
composition
comprises beloxepin that is enriched in the (-) enantiomer. In some
embodiments, the
beloxepin composition comprises substantially enantiomerically pure (-)-
beloxepin. In some
embodiments the beloxepin composition comprises enantiomerically pure (-)-
beloxepin.
[0024] One important class of diseases or disorders known to be responsive to
treatment with
NRIs is mental disease. Specific examples of such mental diseases or disorders
include, but
are not limited to, the various mental diseases and indications classified in
the Diagnostic and
Statistic Manual of Mental Disorders IV (Text Revision 2000; referred to
hereinafter as
"DSM-IV") as mood disorders (such as, for example, depression), anxiety
disorders (such as,
for example OCD), eating disorders, (such as, for example, anorexia nervosa
and bulimia
nervosa), impulse disorders (such as, for example, trichotillomania), sleep
disorders (such as,
for example, insomnia related to opioid withdrawal), personality disorders
(such as, for
example, ADHD), and somatoform disorders (such as certain types of pain).
Another
important class of diseases or indications known to be responsive to treatment
with selective
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NRI compounds is pain, including both acute and chronic pain, whether
nociceptive (for
example somatic or visceral) or non-nociceptive (for example neuropathic or
sympathetic) in
origin (discussed further below). All of these diseases or disorders are
expected to respond to
treatment with various embodiments of the (-)-beloxepin compositions described
herein.
[0025] The (-)-beloxepin composition can be administered alone, or it can be
administered in
combination with, or adjunctively to, one or more other drugs useful for
treating indications
responsive to NRI therapy and/or other indications. Specific non-limiting
examples of drugs
that can be used in combination with, or adjunctively to, the (-)-beloxepin
compositions
described herein in a regimen to treat diseases and/or disorders responsive to
NRI therapy are
provided in a later section.
[0026] In yet another aspect, the present disclosure provides methods of
inhibiting the NE
transporter. Inhibiting this transporter generally results in inhibition of
reuptake of NE. The
methods generally comprise contacting a NE transporter with an amount of (-)-
beloxepin
effective to inhibit the NET. In some embodiments, the method is carried out
in the absence
of (+)-beloxepin. In some embodiments, the NE transporter is contacted with a
(-)-beloxepin
composition as described herein. In some embodiments, the (-)-beloxepin
composition
comprises beloxepin that is enriched in the (-) enantiomer. In some
embodiments, the
(-)-beloxepin composition comprises substantially enantiomerically pure (-)-
beloxepin. In
some embodiments, the (-)-beloxepin composition comprises enantiomerically
pure
(-)-beloxepin.
[0027] The methods can be practiced in vitro with isolated transporters or
cells that express
the NE transporter, or in vivo as a therapeutic approach towards the treatment
of diseases or
disorders that are, at least in part, mediated by dysregulated reuptake of NE.
Specific
examples of diseases or disorders that are, at least in part, mediated by
reuptake of NE
include, but are not limited to, those listed above.
[0028] As noted above, compounds with greater affinity for the NE transporter
are more
effective at treating pain, and compounds with greater affinity for the 5HT
transporter have
limited efficacy (see, e.g., Max et al., 1992; N. Engl. J. Med. 326(19):1250-
1256; Collins et
at., 2000, supra). Therefore, in view of the moderate affinity of (-)-
beloxepin for the NET
(Ki = 390 nM), it would not have been predicted that this compound would be
useful to treat
pain. Notwithstanding that expectation, it has been surprisingly observed
that, in experiments
carried out by the applicants and reported herein, (-)-beloxepin exhibited
robust therapeutic
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efficacy in a rodent model of pain. These data indicate that that (-)-
beloxepin is ideally suited
for the treatment of many different types of pain syndromes.
[0029] Accordingly, in yet another aspect, the present disclosure provides
methods of treating
pain in mammals, including humans. The methods generally comprise
administering to a
mammal suffering from pain, including a human, an amount of a (-)-beloxepin
composition
described herein effective to treat the pain. In some embodiments, the (-)-
beloxepin
composition comprises beloxepin that is enriched in (-) enantiomer. In some
embodiments
the (-)-beloxepin composition comprises substantially enantiomerically pure (-
)-beloxepin.
In some embodiments, the (-)-beloxepin composition comprises enantiomerically
pure
(-)-beloxepin.
[0030] The methods can be used to treat numerous different types of pain
syndromes,
including acute or chronic pain that is either nociceptive in origin (for
example somatic or
visceral) or non-nociceptive in origin (for example neuropathic or
sympathetic). In some
embodiments, the pain is nociceptive pain including, but not limited to,
inflammatory pain
such as that associated with inflammatory bowel syndrome ("IBS") or rheumatoid
arthritis,
pain associated with cancer, and pain associated with osteoarthritis. In some
embodiments
the pain is non-nociceptive pain including, but not limited to, neuropathic
pain such as post-
herpetic neuralgia (PHN), trigeminal neuralgia, focal peripheral nerve injury,
anesthesia
clolorosa, central pain (for example, post-stroke pain, pain due to spinal
cord injury or pain
associated with multiple sclerosis), and peripheral neuropathy (for example,
diabetic
neuropathy, inherited neuropathy or other acquired neuropathies).
[0031] The (-)-beloxepin composition can be administered alone, or it can be
administered in
combination with, or adjunctively to, one or more other drugs useful for
treating pain and/or
other indications. Specific non-limiting examples of drugs that can be used in
combination
with, or adjunctively to, the (-)-beloxepin compositions described herein in a
pain treatment
or pain management regimen are provided in a later section.
[0032] Accordingly, in one aspect, the present disclosure provides
compositions comprising
(+)-beloxepin and optionally one or more acceptable carriers, excipients or
diluents. The
(+)-beloxepin may be present in the composition as a non-racemic mixture
enriched in the
(+) enantiomer. In some embodiments, the (+)-beloxepin is substantially
enantiomerically
pure (+)-beloxepin. In some embodiments, the (+)-beloxepin is enantiomerically
pure.
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[0033] The (+)-beloxepin can be present in the composition in the form of the
free base, or in
the form of a salt. In some embodiments, the (+)-beloxepin is present in the
form of a
pharmaceutically acceptable acid addition salt.
[0034] The (+)-beloxepin composition can be used in vitro or in vivo, as will
be described in
more detail below. When used in vivo, the composition can be formulated for
administration
to animals in veterinary contexts, or for administration to humans via
virtually any route or
mode of administration, including but not limited to, oral, topical, ocular,
buccal, systemic,
nasal, injection, transdermal, rectal, vaginal, inhalation or insufflation. In
some
embodiments, the composition is formulated for oral administration, for
example, to humans.
[0035] Selective and non-selective 5HT2 antagonists have proven effective in
the treatment of
a variety of diseases and disorders. For example, the 5HT2A receptor is known
to mediate, at
least in part, several CNS functions (e.g., neuronal excitation, behavior,
learning, anxiety),
smooth muscle contraction (including vasoconstriction and vasodilation) and
platelet
aggregation. Antagonists of the 5HT2A receptor having established therapeutic
utilities
include, but are not limited to nefazodone (used to treat depression);
trazodone (used to treat
depression with or without anxiety, chronic insomnia, fibromyalgia, control of
nightmares or
disturbed sleep and, off-label, panic disorder, diabetic neuropathy, bulimia
nervosa, obsessive
compulsive disorder, alcohol withdrawal and schizophrenia); mirtazipine (used
to treat
moderate to severe depression and, off-label, panic disorder, anxiety
disorder, obsessive
compulsive disorder, post traumatic stress disorder, sleep apnea, and
pruritis); ketanserin
(classified by the World Health Organization and the NIH as an
antihypertensive);
cyproheptadine (used to treat hay fever and other allergies, stimulate
appetite in underweight
individuals, combat SSRI-induced sexual dysfunction, to treat Cushing's
syndrome and as a
prophylactive for migraines); pizotifen (used as a prophylactive for migraines
and for
treatment of depression and anxiety or social phobia); sarpogrelate (a
selective 5HT2A
receptor antagonist introduced as a therapeutic agent for ischemia associated
with thrombosis
and shown to produce an antinociceptive effect in rat inflammatory pain
models, and to
attenuate primary thermal hyperalgesia and secondary mechanical allodynia
after thermal
injury in rats (Sasaki et at. 2006, Pain 122:130-136, and the references cited
therein),
volinanserin (currently evaluated in Phase III clinical trials for the
treatment of sleep
maintenance insomnia), eplivanserin (currently evaluated in Phase III clinical
trials for the
treatment of sleep maintenance insomnia) and atypical antipsychotics,
including clozapine,
risperidone, olanzapine, quetiepine, ziprasidone, aripiprazole, paliperidone,
asenapine,
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iloperidone, all of which are approved for use in the US, and sertindole,
zotepine,
amisulpride, bifeprunox and meperone, which are approved for use in countries
other than the
US (used to treat a variety of mood and sleep disorders, and in some cases,
psychotic
disorders such as schizophrenia, acute mania, bipolar mania, bipolar
maintenance and
psychotic agitation).
[0036] The potential clinical utility of 5HTzA antagonists has been noted in
WO
2006/100519, where it was stated that such compounds would be effective in the
treatment of
neurological conditions, including sleep disorders such as insomnia, psychotic
disorders such
as schizophrenia, and also depression, anxiety, panic disorder, obsessive-
compulsive
disorder, pain, eating disorders such as anorexia nervosa, and dependency or
acute toxicity
associated with narcotic agents such as LSD or MDMA. Such compounds were
further
alleged to be beneficial in controlling the extrapyramidal symptoms associated
with the
administration of neuroleptic agents. They were also alleged to be effective
in lowering of
intraocular pressure and hence in treating glaucoma, and as effective in
treating menopausal
symptoms, in particular, hot flushes.
[0037] The 5HTzA receptor is also associated with the contraction of vascular
smooth
muscle, platelet aggregation, thrombus formation and coronary artery spasms.
Accordingly,
selective 5HTzA antagonists may have potential in the treatment of
cardiovascular diseases.
For example, sarpogrelate, a selective 5HTzA antagonist, has been introduced
clinically as a
therapeutic agent for the treatment of ischemic diseases associated with
thrombosis
(Nagatomo, et at., 2004, Pharmacology & Therapeutics 104(1):59-81).
[0038] The 5HTzB receptor is known to mediate, at least in part, gastric
contractions.
Yohimbine, a 5HTzA and/or 5HTzB antagonist has been shown in clinical studies
to be useful
in treating male impotence, and has been prescribed for treatment of erectile
dysfunction,
SSRI-induced sexual dysfunction, female hypersexual disorder, post traumatic
stress disorder
(PTSD), and to facilitate recall of traumatic memories in patients with PTSD.
[0039] Antagonists of the 5HTzB receptor have also been asserted as useful for
the treatment
of disorders of the GI tract, especially disorders involving altered mobility,
including irritable
bowel syndrome (WO 01/08668), disorders of gastric motility, dyspepsia, GERD,
tachygastria, migraine/neurogenic pain (WO 97/44326); pain (U.S. Patent No.
5,958,934);
anxiety and depression (WO 97/44326); benign prostatic hyperplasia (U.S.
Patent No.
5,952,221); sleep disorders (WO 97/44326); panic disorder, obsessive-
compulsive disorder,
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alcoholism, hypertension, anorexia nervosa, and priapism (WO 97/44326); asthma
and
obstructive airway disease (U.S. Patent No. 5,952,331); incontinence and
bladder dysfunction
(WO 96/24351); disorders of the uterus, such as dysmenorrhea, pre-term labor,
post-partum
remodelling, endometriosis, and fibrosis; and pulmonary hypertension (Launay,
et at, 2002,
Nature Medicine 8(10):1129-1135).
[0040] The 5HT2c receptor is known to mediate, at least in part, several CNS
functions
(anxiety, choroid plexus), and cerebrospinal fluid (CSF) secretion.
Antagonists of the 5HT2c
receptor having established therapeutic utilities include, but are not limited
to, mesulergine
(possibly useful for treating Parkinson's disease); agomelatine (currently in
development for
treatment of depression by Novartis); and methysergide (useful for treating
and prophylaxis
of migraine headaches). It is expected that all of these diseases and
disorders will likewise
respond to treatment with (+)-beloxepin.
[0041] Antagonists of the 5HT2c receptor have also been asserted as useful for
the treatment
of CNS disorders such as anxiety, depression (both bipolar and unipolar),
single or recurrent
major depressive episodes, with or without psychotic features, catatonic
features, melancholic
features, atypical features or postpartum onset, dysthymic disorders with
early or late onset
and with or without atypical features, neurotic depression, post traumatic
stress disorder,
social phobia, vascular dementia with depressed mood, mood disorders induced
by alcohol,
amphetamines, cocaine, hallucinogens, inhalants, opioids, phencyclidine,
sedatives,
hypnotics, anxiolytics and the like; schizoaffective disorder of the depressed
type, adjustment
disorder with depressed mood, epilepsy, obsessive compulsive disorders,
migraine,
Alzheimer's disease, with early or late onset and/or with depressed mood;
cognitive disorders
including dementia, amnestic disorders and cognitive disorders not otherwise
specified, sleep
disorders (including disturbances of Circadian rhythm, dyssomnia, insomnia,
sleep apnea and
narcolepsy), feeding disorders such as anorexia, anorexia nervosa and bulimia;
panic attacks,
withdrawal from drug abuse such as of cocaine, ethanol, nicotine,
benzodiazepoines, caffeine,
phencyclidine, opiates (e.g. cannabis, heroin, morphine), sedative ipnotic,
amphetamines,
schizophrenia, and also disorders associated with spinal trauma and/or head
injury such as
hydrocephalus. Antagonists of the 5-HT2B receptor have also been asserted as
useful as
memory and/or cognition enhancers in healthy humans with no cognitive and/or
memory
deficit (see WO 02/14273).
[0042] Thus, in another aspect, the present disclosure provides methods of
treating diseases
and disorders responsive to treatment with 5HT2 antagonist compounds. The
methods
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generally comprise administering to a mammal, including a human, suffering
from a disease
or indication responsive to treatment with a 5HT2 antagonist compound an
amount of a
(+)-beloxepin composition described herein effective to treat the disease or
disorder. In some
embodiments, the disease or disorder is responsive to treatment with a
compound that
antagonizes one of the 5HT2A, 5HT2B or 5HT2c receptors. Non-limiting examples
of diseases
and disorders that respond to treatment with 5HT2A, 5HT2B, 5HT2c selective and
non-
selective antagonists are provided above (also see Leysen, 2004, Current Drug
Targets: CNS
& Neurological Disorders 3(1):11-26).
[0043] In some embodiments, the disease or disorder is responsive to treatment
with a dual
antagonist that antagonizes 5HT2A, 2B, 5HT2A, 2C, or 5HT2B, 2C.
[0044] In some embodiments the disease or disorder is responsive to treatment
with a triple
5HT2A, 2B, 2C antagonist.
[0045] In some embodiments, the (+)-beloxepin composition comprises beloxepin
that is
enriched in the (+) enantiomer. In some embodiments, the beloxepin composition
comprises
substantially enantiomerically pure (+)-beloxepin. In some embodiments the
beloxepin
composition comprises enantiomerically pure (+)-beloxepin.
[0046] The (+)-beloxepin composition can be administered alone, or it can be
administered in
combination with, or adjunctively to, one or more other drugs useful for
treating indications
responsive to 5HT antagonist compounds and/or other indications. Specific non-
limiting
examples of drugs that can be used in combination with, or adjunctively to,
the (+)-beloxepin
compositions described herein in a regimen to treat diseases and/or disorders
responsive to
5HT2 antagonist therapy are provided in a later section.
[0047] In yet another aspect, the present disclosure provides methods of
antagonizing 5HT2
receptors, including the 5HT2A, 5HT2B and/or 5HT2c receptor subtypes. The
methods
generally comprise contacting a 5HT2 receptor with an amount of (+)-beloxepin
effective to
antagonize the receptor (as measured in a conventional cellular assay). In
some
embodiments, the method is carried out in the absence of (-)-beloxepin. In
some
embodiments, the 5HT2 receptor is contacted with a (+)-beloxepin composition
as described
herein. In some embodiments, the (+)-beloxepin composition comprises beloxepin
that is
enriched in the (+) enantiomer. In some embodiments, the (+)-beloxepin
composition
comprises substantially enantiomerically pure (+)-beloxepin. In some
embodiments, the
(+)-beloxepin composition comprises enantiomerically pure (+)-beloxepin.
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[0048] The methods can be practiced in vitro with isolated receptors or cells
that express one
or more of the 5HT2 receptor subtypes 2A, 2B or 2C, or in vivo as a
therapeutic approach
towards the treatment of diseases or disorders that are, at least in part,
mediated by
antagonisms of the 5HT2 receptor, including one or more of the 5HT2A, 5HT2B
and 5HT2c
receptor subtypes. Specific examples of diseases or disorders that are, at
least in part,
mediated by such receptor antagonism include, but are not limited to, those
listed above.
[0049] The (+) enantiomer of beloxepin is also useful for treating pain.
Indeed, in
experiments carried out by the applicants and reported herein, (+)-beloxepin
exhibited
therapeutic efficacy in a rodent model of pain.
[0050] Accordingly, in yet another aspect, the present disclosure provides
methods of treating
pain in mammals, including humans. The methods generally comprise
administering to a
mammal suffering from pain, including a human, an amount of a (+)-beloxepin
composition
described herein effective to treat the pain. In some embodiments, the (+)-
beloxepin
composition comprises beloxepin that is enriched in (+) enantiomer. In some
embodiments
the (+)-beloxepin composition comprises substantially enantiomerically pure
(+)-beloxepin.
In some embodiments, the (+)-beloxepin composition comprises enantiomerically
pure
(+)-beloxepin.
[0051] The methods can be used to treat numerous different types of pain
syndromes,
including acute or chronic pain that is either nociceptive in origin (for
example somatic or
visceral) or non-nociceptive in origin (for example neuropathic or
sympathetic). In some
embodiments, the pain is nociceptive pain including, but not limited to,
inflammatory pain
such as that associated with IBS or rheumatoid arthritis, pain associated with
cancer, and pain
associated with osteoarthritis. In some embodiments the pain is non-
nociceptive pain
including, but not limited to, neuropathic pain (such as post-herpetic
neuralgia, trigeminal
neuralgia, focal peripheral nerve injury, anesthesia clolorosa), central pain
(for example, post-
stroke pain, pain due to spinal cord injury or pain associated with multiple
sclerosis), and
peripheral neuropathy (for example, diabetic neuropathy, inherited neuropathy
or other
acquired neuropathies).
[0052] The (+)-beloxepin composition can be administered alone, or it can be
administered in
combination with, or adjunctively to, one or more other drugs useful for
treating pain and/or
other indications. Specific non-limiting examples of drugs that can be used in
combination
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with, or adjunctively to, the (+)-beloxepin compositions described herein in a
pain treatment
or management regimen are provided in a later section.
[0053] Analogs of beloxepin are known in the art. For example, analogs of
beloxepin are
described in US Patent No. 4,977,158, the disclosure of which is incorporated
herein by
reference. These analogs are expected to exhibit anti-pain activities similar
to beloxepin.
[0054] Accordingly in one aspect, the present disclosure provide a method of
treating pain in
a mammal comprising administering to a mammal suffering from pain, including a
human, an
amount of beloxepin and/or a beloxepin analog effective to treat the pain.
[0055] The beloxepin or beloxepin analog can be administered as the compound
per se, or in
the form of a composition. The beloxepin or beloxepin analog can be included
in the
composition as the free base, or in the form of a salt. In some embodiments
the beloxepin
and/or beloxepin analog is included in the composition in the form of a
pharmaceutically
acceptable salt.
[0056] The composition can be formulated for administration to animals in
veterinary
contexts, or for administration to humans, via virtually any route or mode of
administration,
including, but not limited to, oral, topical, ocular, buccal, systemic, nasal,
injection,
transdermal, rectal, vaginal, inhalation or insufflation. In some embodiments,
the
composition is formulated for oral administration, for example, to humans.
[0057] The methods can be used to treat numerous different types of pain
syndromes,
including acute or chronic pain that is either nociceptive (for example
somatic or visceral) or
non-nociceptive (for example neuropathic or sympathetic) in origin. In some
embodiments,
the pain is nociceptive pain including, but not limited to, surgical pain,
inflammatory pain
such as that associated with inflammatory bowel syndrome ("IBS") or rheumatoid
arthritis,
pain associated with cancer, and pain associated with osteoarthritis. In some
embodiments,
the pain is non-nociceptive pain including, but not limited to, neuropathic
pain such as post-
herpetic neuralgia ("PHN"), trigeminal neuralgia, focal peripheral nerve
injury, anesthesia
clolorosa, central pain (for example, post-stroke pain, pain due to spinal
cord injury or pain
associated with multiple sclerosis), and peripheral neuropathy (for example,
diabetic
neuropathy, inherited neuropathy or other acquired neuropathies).
[0058] The beloxepin and/or beloxepin analog can be administered alone, or it
can be
administered in combination with, or adjunctively to, one or more other drugs
useful for
treating pain and/or other indications. Specific non-limiting examples of
drugs that can be
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used in combination with, or adjunctively to, the beloxepin and/or beloxepin
analogs in a pain
treatment or management regimen are provided in a later section. In one
specific
embodiment, beloxepin is administered in combination with, or adjunctively to,
one or more
beloxepin analogs.
[0059] As noted above, analogs of beloxepin have been reported in the art. For
example, US
Patent No. 4,977,158, the disclosure of which is incorporated herein by
reference, discloses
beloxepin analogs according to structural formula (I):
R5
( N
n
R3 R4
(I) R1 X R~
wherein:
n is 0 or 1;
Xis0orS;
Ri represents one or two identical or different substituents selected from H,
OH, halogen, Ci-C4 alkyl and Ci-C4 alkoxy;
R2 represents one or two identical or different substituents selected from H,
OH, halogen, Ci-C4 alkyl and Ci-C4 alkoxy;
R3 and R4 are two substituents which are in the cis configuration and R3 is OH
and R4 is H; and
R5 is H or Ci-C4 alkyl.
[0060] It is expected that these beloxepin analogs comprise racemates and (+)-
cis and (-)-cis
enantiomers having distinct biological activities that correlate with the
activities of the
corresponding ( )-, (+)- and (-)-beloxepin isomers. Accordingly, the various
enantiomers of
the beloxepin analogs of structural formula (I) that correspond to the (-)
enantiomer of
beloxepin can be used in the compositions and methods described herein.
7. BRIEF DESCRIPTION OF THE FIGURES
[0061] FIG. 1 provides a graph demonstrating the antiallodynic effect of
beloxepin (30 mg/kg
IP) in L5 SNL rats 14 days post surgery;
[0062] FIG. 2 provides a graph demonstrating the antiallodynic effect of
beloxepin (3, 10 and
30 mg/kg IP) in L5 SNL rats 16 days post surgery;
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[0063] FIG. 3 provides a graph illustrating the superior antiallodynic effect
of beloxepin (30
mg/kg IP) as compared to reboxetine, a selective norepinephrine reuptake
inhibitor (30 mg/kg
IP), in L5 SNL rats;
[0064] FIG. 4 provides a graph demonstrating the antiallodynic effect of
orally administered
beloxepin (60 mg/kg PO) in L5 SNL rats 8 days post surgery;
[0065] FIG. 5 provides a graph comparing the antiallodynic effects produced by
beloxepin,
duloxetine, amitriptyline, and reboxetine (each at a concentration of 30 mg/kg
IP) in L5 SNL
rats;
[0066] FIGS. 6A and 6B provide graphs demonstrating the robust anti-
nociceptive activity
of beloxepin in a rodent model of acute nociception;
[0067] FIG. 7 provides a graph illustrating the robust antihyperalgesia
activity of beloxepin
in an animal model of inflammatory pain (rats treated with Freund's Complete
Adjuvent);
[0068] FIG. 8 provides a graph illustrating the robust activity of beloxepin
in a rodent model
of visceral pain (mice treated with acetic acid);
[0069] FIG. 9 provides a graph comparing the mechanical antihyperalgesic
effects of
(30 mg/Kg IP) ( )-beloxepin and a reconstituted equimolar (racemic) mixture
(30 mg/Kg IP)
of (+)-beloxepin and (-)-beloxepin, in FCA-treated rats, 24 hours after FCA
injection;
[0070] FIG. 10 provides a graph demonstrating the antiallodynic effect of
orally administered
beloxepin (60 mg/kg PO) in L5 SNL rats 7 days post surgery;
[0071] FIG. 11 provides a graph comparing the antiallodynic effects of
beloxepin, duloxetine,
and esreboxetine (each compound dosed at 30 mg/kg IP) in L5 SNL rats;
[0072] FIG. 12 provides a graph demonstrating the antiallodynic effect of
beloxepin (30
mg/kg IP) in the rat hindpaw incisional model 24 hours post surgery;
[0073] FIG. 13 provides a graph demonstrating the antiallodynic effect of
orally-administered
beloxepin (60 mg/kg IP) in the rat hindpaw incisional model 24 hours post
surgery; and
[0074] FIG. 14 provides a graph demonstrating the antiallodynic effect of
intravenously-administered beloxepin (3 mg/kg IV) in the rat hindpaw
incisional model 24
hours post surgery.
[0075] FIG. 15 provides a graph illustrating the inhibition of CYP2D6
(dextromethorphan
O-demethylation) by beloxepin and quinidine.
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[0076] FIG. 16 provides a graph demonstrating the antiallodynic effect of (+)-
and
(-)-beloxepin (30 mg/kg IP) in L5 SNL rats 8 days post surgery;
[0077] FIG. 17 provides a graph demonstrating the antiallodynic effect of (-)-
beloxepin (30
mg/kg IP) in L5 SNL rats 14 days post surgery;
[0078] FIG. 18 provides a graph demonstrating the antiallodynic effect of
orally administered
(-)-beloxepin (60 mg/kg PO) in L5 SNL rats 7 days post surgery;
[0079] FIG. 19 provides a graph demonstrating the antiallodynic effect of
orally administered
(+)-beloxepin (60 mg/kg PO) in L5 SNL rats 14 days post surgery;
[0080] FIG. 20 provides a graph demonstrating the antiallodynic effect of (-)-
beloxepin (30
mg/kg IP) in the rat hindpaw incisional model 24 hours post surgery;
[0081] FIG. 21 provides a graph demonstrating the antiallodynic effect of (+)-
beloxepin (30
mg/kg IP) in the rat hindpaw incisional model 24 hours post surgery;
[0082] FIG. 22 provides a graph depicting the antinociceptive effects of (-)-
beloxepin
(30 mg/Kg) in the rat 50 C hot plate model; and
[0083] FIG. 23 provides a graph depicting the antinociceptive effects of (+)-
beloxepin
(30 mg/Kg) in the rat 50 C hot plate model.
8. DETAILED DESCRIPTION
[0084] The present disclosure concerns the use of beloxepin and/or its analogs
to treat pain.
The disclosure is based, in part, on the surprising discovery that beloxepin,
which is a weak
selective inhibitor of NE reuptake, nonetheless produces significant and
robust activity across
a broad spectrum of rodent models of various types of pain syndromes,
including rodent
models of acute nociceptive pain, inflammatory pain, visceral pain and
neuropathic pain. As
discussed in the Summary, inhibition of NE reuptake correlates with efficacy
in the treatment
of pain (see, Max et at., 1992, supra; Collins et at., 2000, supra; Atkinson
et at., 1999, supra;
Levental et at., 2007, supra). Based on its weak activity at the NET,
beloxepin would not be
expected to be useful in treating pain. Yet, it produces robust activity in
numerous animal
models of pain, and in the case of tactile anitallodynia, activity of
magnitude greater than that
observed with numerous compounds known to be effective in treating pain.
[0085] The present disclosure is also directed to, among other things,
compositions
comprising the (-) enantiomer of racemic ( )-beloxepin, and methods of use of
the
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(-)-enantiomer of racemic ( )-beloxepin and compositions comprising the (-)-
enantiomer of
racemic ( )-beloxepin
[0086] The present disclosure is further directed to, among other things,
compositions
comprising the (+) enantiomer of racemic ( )-beloxepin, and methods of use of
the
(+)-enantiomer of racemic ( )-beloxepin and compositions comprising the (+)-
enantiomer of
racemic ( )-beloxepin.
8.1 Beloxepin Compounds And Compositions
[0087] Racemic beloxepin (( )-beloxepin), i.e., "beloxepin," also known as
"Org-4428" and
"cis- 1,2,3,4,4a, 13b-hexahydro-2,10-dimethyldiben-[2,3:6,7]oxepino
[4,5c]pyridine-4a-ol]," is
illustrated below:
N
HO H
0
The OH and H substituents attached to the carbon atoms marked with asterisks
are in the cis
configuration with respect to one another. Since these carbons are chiral,
this cis geometric
isomer is a racemic mixture of two enantiomers, a (+) enantiomer and a (-)
enantiomer. The
absolute configurations about the chiral carbons of these (+) and (-)
enantiomers are not
presently known.
[0088] Analogs of beloxepin have been reported in the art. For example, US
Patent No.
4,977,158, the disclosure of which is incorporated herein by reference,
discloses beloxepin
analogs according to structural formula (I):
R5
( N
n
R4
(I) Wax ~ R2
wherein:
n is 0 or 1;
Xis0orS;
RI represents one or two identical or different substituents selected from H,
OH, halogen, CI-C4 alkyl and CI-C4 alkoxy;
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R2 represents one or two identical or different substituents selected from H,
OH, halogen, CI-C4 alkyl and CI-C4 alkoxy;
R3 and R4 are two substituents which are in the cis configuration, where R3 is
OH and R4 is H; and
R5 is H or CI-C4 alkyl.
[0089] These analogs are expected to have biological and pharmacological
properties similar
to beloxepin, and are therefore also expected to be effective in treating and
managing various
pain syndromes as described herein. Beloxepin analogs according to structural
formula (I)
are referred to herein as "beloxepin analogs," or other grammatical
equivalents. Thus, the
beloxepin analogs can be used in the various compositions and methods
described herein and
the various illustrative embodiments described for beloxepin apply also to the
beloxepin
analogs as if such embodiments were specifically described.
[0090] Beloxepin, its (+)- and (-)-enantiomers, and/or the analogs thereof
(i.e. analogs of
beloxepin, (+)- beloxepin, and (-)-beloxepin), can be used in the various
methods described
herein as the compound per se, or can be included in a composition formulated
for, among
other things, a specific mode of administration. The beloxepin or beloxepin
analog can be
present in the composition as the free base, or in the form of a salt, for
example, an acid
additional salt. In some embodiments, such salts are pharmaceutically
acceptable salts.
[0091] As used herein, a racemic composition is "enriched" in a particular
enantiomer when
that enantiomer is present in excess over the other enantiomer, i.e., when
that enantiomer
comprises more than 50% of the total beloxepin in the composition. A
composition that is
enriched in a particular enantiomer will typically comprise at least about
60%, 70%, 80%,
90%, or even more, of the specified enantiomer. The amount of enrichment of a
particular
enantiomer can be confirmed using conventional analytical methods routinely
used by those
skilled in the art, including NMR spectroscopy in the presence of chiral shift
reagents, gas
chromatographic analysis using chiral columns, and high pressure liquid
chromatographic
analysis using chiral columns.
[0092] In some embodiments, a single enantiomer will be substantially free of
the other
enantiomer. By "substantially free of is meant that the composition comprises
less than
about 10% of the specified undesired enantiomer, as established using
conventional analytical
methods routinely used by those of skill in the art, such as the methods
mentioned above. In
some embodiments, the amount of undesired enantiomer comprising the compound
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composition maybe less than 10%, for example, 9%,8%,7%,6%,5%,4%,3%,2%, 1% or
even less. Enantiomerically enriched compound compositions that contain at
least about 90%
of a specified enantiomer are referred to herein as "substantially
enantiomerically pure."
Thus, substantially enantiomerically pure compositions of chirally active
compounds can
contain in the range of at least about 90%, 91%, 92%, 93%, 94%, 95%, 96% or
97%, or even
more (including any amount falling with the range of about 90-100%) of a
specified
enantiomer. Compositions of chirally active compounds that contain at least
about 98% of a
specified enantiomer are referred to herein as "enantiomerically pure." Thus,
enantiomerically pure compositions of chirally active compounds can contain in
the range of
at least about 98%, 99%, or even more (including any amount falling with the
range of about
98-100%) of a specified enantiomer.
[0093] Structural formula (I) is beloxepin when X is 0, n is 1, R1 and R4 are
each H, R2 is
2-methyl, R3 is OH and R5 is methyl. Although various aspects of the instant
disclosure are
illustrated herein with (-)-beloxepin, it is expected that analogs of
beloxepin according to
structural formula (I), above, in which the configurations about the carbon
atoms marked
with asterisks relative to the oxepin ring are the same as those of (-)-
beloxepin (referred to
herein as "corresponding (-)-beloxepin analogs" or "corresponding enantiomers"
or other
grammatical equivalents) will have biological activities, and thus therapeutic
uses, similar to
those of (-)-beloxepin. Thus, the corresponding (-)-beloxepin analogs can also
be used in the
various compositions and methods described herein, and the various
illustrative embodiments
described for (-)-beloxepin apply also to the corresponding (-)-beloxepin
analogs as if such
embodiments were specifically described.
[0094] In the various (-)-beloxepin compositions described herein, the
beloxepin can be
present as a non-racemic mixture enriched in the (-) enantiomer, as the
substantially
enantiomerically pure (-) enantiomer or as the enantiomerically pure (-)
enantiomer. In
specific embodiments, the compositions comprise substantially enantiomerically
pure
(-)-beloxepin or enantiomerically pure (-)-beloxepin. Methods for synthesizing
racemic
beloxepin and isolating the (-) enantiomer via chiral separation are described
in a later
section.
[0095] Depending upon the intended use, the (-)-beloxepin can be present in
the composition
as the free base, or in the form of a salt, for example, an acid additional
salt. In some
embodiments, the (-)-beloxepin is present in the composition in the form of a
pharmaceutically acceptable salt. Generally, pharmaceutically acceptable salts
are those salts
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that retain substantially one or more of the desired pharmacological
activities of the parent
compound and which are suitable for administration to humans. Pharmaceutically
acceptable
salts include acid addition salts formed with inorganic acids or organic
acids. Inorganic acids
suitable for forming pharmaceutically acceptable acid addition salts include,
by way of
example and not limitation, hydrohalide acids (e.g., hydrochloric acid,
hydrobromic acid,
hydriodic, etc.), sulfuric acid, nitric acid, phosphoric acid and the like.
Organic acids suitable
for forming pharmaceutically acceptable acid addition salts include, by way of
example and
not limitation, acetic acid, trifluoroacetic acid, propionic acid, hexanoic
acid,
cyclopentanepropionic acid, glycolic acid, oxalic acid, pyruvic acid, lactic
acid, malonic acid,
succinic acid, malic acid, maleic acid, fumaric acid, tartaric acid, citric
acid, palmitic acid,
benzoic acid, 3-(4-hydroxybenzoyl) benzic acid, cinnamic acid, mandelic acid,
alkylsulfonic
acids (e.g., methanesulfonic acid, ethanesulfonic acid, 1,2-ethane-disulfonic
acid, 2-
hydroxyethanesulfonic acid, etc.), arylsulfonic acids (e.g., benzenesulfonic
acid,
4-chlorobenzenesulfonic acid, 2-naphthalenesulfonic acid, 4-tuluenesulfonic
acid,
camphorsulfonic acid, etc.), 4-methylbicyclo[2.2.2]-oct-2-ene-l-carboxylic
acid,
glucoheptonic acid, 3-phenylpropionic acid, trimethylacetic acid, tertiary
butylacetic acid,
lauryl sulfuric acid, gluconic acid, glutamic acid, hydroxynaphthoic acid,
salicylic acid,
stearic acid, muconic acid, and the like.
[0096] In some embodiments, the (-)-beloxepin is present in the composition as
the free base.
In some embodiments, the (-)-beloxepin is present in the composition as an
organic acid
addition salt.
[0097] Structural formula (I) is beloxepin when X is 0, n is 1, R1 and R4 are
each H, R2 is
2-methyl, R3 is OH and R5 is methyl. Although various aspects of the instant
disclosure are
illustrated herein with (+)-beloxepin, it is expected that analogs of
beloxepin according to
structural formula (I), above, in which the configurations about the carbon
atoms marked
with asterisks relative to the oxepin ring are the same as those of (+)-
beloxepin (referred to
herein as "corresponding (+)-beloxepin analogs" or "corresponding enantiomers"
or other
grammatical equivalents) will have biological activities, and thus therapeutic
uses, similar to
those of (+)-beloxepin. Thus, the corresponding (+)-beloxepin analogs can also
be used in
the various compositions and methods described herein and the various
illustrative
embodiments described for the (+)-beloxepin apply also to the corresponding
(+)-beloxepin
analogs as if such embodiments were specifically described.
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[0098] In the various (+)-beloxepin compositions described herein, the
beloxepin can be
present as a non-racemic mixture enriched in the (+) enantiomer, as the
substantially
enantiomerically pure (+) enantiomer or as the enantiomerically pure (+)
enantiomer. In
specific embodiments, the compositions comprise substantially enantiomerically
pure
(+)-beloxepin or enantiomerically pure (+)-beloxepin. Methods for synthesizing
racemic
beloxepin and isolating the (+) enantiomer via chiral separation are described
in a later
section.
[0099] Depending upon the intended use, the (+)-beloxepin can be present in
the composition
as the free base, or in the form of a salt, for example, an acid additional
salt. In some
embodiments, the (+)-beloxepin is present in the composition in the form of a
pharmaceutically acceptable salt. Generally, pharmaceutically acceptable salts
are those salts
that retain substantially one or more of the desired pharmacological
activities of the parent
compound and which are suitable for administration to humans. Pharmaceutically
acceptable
salts include acid addition salts formed with inorganic acids or organic
acids. Inorganic acids
suitable for forming pharmaceutically acceptable acid addition salts include,
by way of
example and not limitation, hydrohalide acids (e.g., hydrochloric acid,
hydrobromic acid,
hydriodic, etc.), sulfuric acid, nitric acid, phosphoric acid and the like.
Organic acids suitable
for forming pharmaceutically acceptable acid addition salts include, by way of
example and
not limitation, acetic acid, trifluoroacetic acid, propionic acid, hexanoic
acid,
cyclopentanepropionic acid, glycolic acid, oxalic acid, pyruvic acid, lactic
acid, malonic acid,
succinic acid, malic acid, maleic acid, fumaric acid, tartaric acid, citric
acid, palmitic acid,
benzoic acid, 3-(4-hydroxybenzoyl) benzic acid, cinnamic acid, mandelic acid,
alkylsulfonic
acids (e.g., methanesulfonic acid, ethanesulfonic acid, 1,2-ethane-disulfonic
acid, 2-
hydroxyethanesulfonic acid, etc.), arylsulfonic acids (e.g., benzenesulfonic
acid,
4-chlorobenzenesulfonic acid, 2-naphthalenesulfonic acid, 4-tuluenesulfonic
acid,
camphorsulfonic acid, etc.), 4-methylbicyclo[2.2.2]-oct-2-ene-l-carboxylic
acid,
glucoheptonic acid, 3-phenylpropionic acid, trimethylacetic acid, tertiary
butylacetic acid,
lauryl sulfuric acid, gluconic acid, glutamic acid, hydroxynaphthoic acid,
salicylic acid,
stearic acid, muconic acid, and the like.
[0100] In some embodiments the (+)-beloxepin is present in the composition as
the free base.
In some embodiments, the (+)-beloxepin is present in the composition as an
organic acid
addition salt.
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[0101] Generally, "pharmaceutically acceptable salts" are those salts that
retain substantially
one or more of the desired pharmacological activities of the parent compound
and which are
suitable for administration to humans. Pharmaceutically acceptable salts
include, but are not
limited to, acid addition salts formed with inorganic or organic acids.
Inorganic acids
suitable for forming pharmaceutically acceptable acid addition salts include,
by way of
example and not limitation, hydrohalide acids (e.g., hydrochloric acid,
hydrobromic acid,
hydriodic, etc.), sulfuric acid, nitric acid, phosphoric acid and the like.
Organic acids suitable
for forming pharmaceutically acceptable acid addition salts include, by way of
example and
not limitation, acetic acid, trifluoroacetic acid, propionic acid, hexanoic
acid,
cyclopentanepropionic acid, glycolic acid, oxalic acid, pyruvic acid, lactic
acid, malonic acid,
succinic acid, malic acid, maleic acid, fumaric acid, tartaric acid, citric
acid, palmitic acid,
benzoic acid, 3-(4-hydroxybenzoyl) benzic acid, cinnamic acid, mandelic acid,
alkylsulfonic
acids (e.g., methanesulfonic acid, ethanesulfonic acid, 1,2-ethane-disulfonic
acid, 2-
hydroxyethanesulfonic acid, etc.), arylsulfonic acids (e.g., benzenesulfonic
acid, 4-
chlorobenzenesulfonic acid, 2-naphthalenesulfonic acid, 4-tuluenesulfonic
acid,
camphorsulfonic acid, etc.), 4-methylbicyclo[2.2.2]-oct-2-ene-l-carboxylic
acid,
glucoheptonic acid, 3-phenylpropionic acid, trimethylacetic acid, tertiary
butylacetic acid,
lauryl sulfuric acid, gluconic acid, glutamic acid, hydroxynaphthoic acid,
salicylic acid,
stearic acid, muconic acid, and the like.
8.2 Methods Of Synthesis
[0102] Beloxepin can be synthesized or prepared using methods described in the
literature,
for example, beloxepin can be synthesized as described in US Patent No.
4,977,158, the
disclosure of which is incorporated herein by reference, and the (+) and (-)
enantiomers
isolated by conventional chiral chromatography (see, e.g., Chiral Separation
Techniques: A
Practical Approach, 2nd ed., Wiley-VCH, Weinheim, 2001). Beloxepin analogs can
also be
synthesized using the methods described in US Patent No. 4,977,158 and the
corresponding
(+) and (-) enantiomers isolated by conventional chiral chromatography.
[0103] A specific method for synthesizing racemic beloxepin which can be
routinely adapted
to synthesize racemic beloxepin analogs, and from which the corresponding (+)
and (-)
enantiomers can be isolated is illustrated in Scheme 1, below:
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Scheme 1
CS2CO3,CUCI \
TDA, DM F
80 C, 24-48 hr / PPA O
OH OH 45-50% yield sulfolane a ,,,0" HO \ 120 C
0 80%
TDA B C
4 O HO
NH2Me,TBTU HN
Br--'~-O TFA/DCM 0 O DIEA, THE** O O
4rD, NaH/THF, 0 C 94% 93%
\ 78% / 0 / \ -
E F
NH NH BH DMS -N
NaBH4 O OH 3 OH BOC2O
MeOH/THF THE T~ OH
97% I / 0 / \ 802% 0 100%
G H 0
I
O
NH
1. Ms-Cl N O /
TEA, DCM HCl in Et20 2N HCl N
_ DCM _ Formaldehyde
2. DBU 91 % I / / \ 5 JHO H
Toluene 0 66%
0
56% 0 66/o
K L
/ /
N N
Chiral separation HO H HO H
M N
[0104] Specific synthetic details, as well as the conditions used for the
chiral separation of
the (+) and (-) beloxepin enantiomers are provided in the Examples section.
8.3 Uses Of Beloxepin And Its Analogs
[0105] Pain is generally understood to refer to the perception or condition of
unpleasant
sensory or emotional experience, which may or may not be associated with
actual damage to
tissues. It is generally understood to include two broad categories: acute and
chronic (see,
e.g., Analgesics, Buschmann et al., Wiley-VCH, Verlag GMbH & Co. KgaA,
Weinheim,
2002; Jain, 2000, Emerging Drugs 5(2):241-257) that is either of nociceptive
origin (for
example somatic or visceral) or non-nociceptive origin (for example
neuropathic or
sympathetic). Acute pain generally includes nociceptive pain arising from
strains/sprains,
bums, myocardial infarction, acute pancreatitis, surgery, trauma and cancer.
Chronic pain
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generally includes nociceptive pain, including, but not limited to,
inflammatory pain such as
that associated with IBS or rheumatoid arthritis, pain associated with cancer
and pain
associated with osteoarthritis; and non-nociceptive pain, including, but not
limited to,
neuropathic pain such as post-herpetic neuralgia, trigeminal neuralgia, focal
peripheral nerve
injury, anesthesia clolorosa, central pain (for example, post-stroke pain,
pain due to spinal
cord injury or pain associated with multiple sclerosis), and peripheral
neuropathy (for
example, diabetic neuropathy, inherited neuropathy or other acquired
neuropathies).
[0106] Data presented in the Examples section confirm that beloxepin is
surprisingly
effective at treating pain in rodent models of neuropathic, acute nociceptive,
inflammatory
and visceral pain. Based upon this animal data, it is expected that beloxepin
and beloxepin
analogs will be useful in treating various different pain syndromes including,
but not limited
to, acute pain of nociceptive origin, such as, for example, surgical pain,
chronic pain of
nociceptive origin, such as, for example, inflammatory pain or cancer pain,
and chronic pain
of non-nociceptive origin, such as, for example, neuropathic pain.
[0107] In general, a "therapeutically effective" amount of a compound or
composition is an
amount that eradicates or ameliorates the underlying disease or indication
being treated
and/or that eradicates or ameliorates one or more of the symptoms associated
with the
underlying disorder such that the patient reports an improvement in feeling or
condition, not
withstanding that the patient may still be afflicted with the underlying
disease or indication.
Therapeutic benefits also includes halting or slowing the progression of the
disease or
indication, regardless of whether improvement is realized.
[0108] In the context of depression, a therapeutically effective amount is an
amount of
composition that eradicates or ameliorates the depression or the symptoms
thereof, including,
but not limited to, changes in mood, feeling of intense sadness, despair,
mental slowing, loss
of concentration, pessimistic worry, agitation, self-deprecation, insomnia,
anorexia, weight
loss, decreased energy and libido, and hormonal circadian rhythms.
[0109] In the context of anxiety disorder, a therapeutically effective amount
is an amount of
composition that eradicates or ameliorates the anxiety disorder or one of the
symptoms
thereof including, but are not limited to, a fear of losing control of one's
own actions, a sense
of terror arising from no apparent reason, a dread of catastrophe, uneasiness,
nervousness,
nagging uncertainty about future events, headaches, fatigue, and sub-acute
autonomic
symptoms.
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[0110] In the context of pain, a therapeutically effective amount is an amount
of composition
that eradicates or ameliorates the pain or the symptoms thereof, including,
but not limited to,
shooting sensations, burning sensations, electrical sensations, aching,
discomfort, soreness,
tightness, stiffness, sleeplessness, numbness, and weakness. An effective
amount may also
be an amount of a composition that blocks the onset of pain or the symptoms
thereof. Thus,
the composition may be administered therapeutically after the onset of
sensation of pain or
one or more of its symptoms, and/or prophylactically prior to the onset of
sensation of pain or
one or more of its symptoms. Is some embodiments, the composition may be
administered in
response to the sensation of pain or one or more of its symptoms and
prophylactically
thereafter to avoid its recurrence.
[0111] As described in more detail in Example 2, (-)-beloxepin binds the
norepinephrine
("NE") transporter, and inhibits NE reuptake. The use of NRI compounds to
treat a variety of
diseases and disorders mediated, at least in part, by dysregulated NE reuptake
is well
documented. For example, the NRI atomoxetine (sold under the tradename
STATTERA by
Eli Lilly & Co.) is approved in the US for the treatment of attention deficit
disorder (ADD)
and attention deficit hyperactivity disorder (ADHD); the NRI reboxetine (sold
under the
tradename EDRONAX by Pharmacia-Upjohn) is approved in the UK and Ireland for
the
treatment of depressive illness; the NRI viloxazine (sold under the tradename
VIVALAN by
AstraZeneca) is approved in the US for the treatment of depression; the NRI
maprotiline
(sold under the tradename LUDIOMIL by Ciba-Geigy Corporation) is approved in
the US for
the treatment of depressive illness in patients with depressive neurosis
(dysthymic disorder),
manic-depressive illness, major depressive disorder and the relief of anxiety
associated with
depression; and the NRI nortriptyline (sold under the tradename Aventyl by
Eli Lilly) is
approved in the US for the treatment of depressive disorders.
[0112] The ability of racemic ( )-beloxepin to cross the blood-brain barrier
has been
established in the literature (beloxepin has a reported logBB of 0.82; Kelder
et at., 1999,
Pharm. Res. 16:1514). Accordingly, the (-)-beloxepin compositions described
herein are
expected to be useful to treat any disease and/or disorder mediated, at least
in part, by
dysregulated NE reuptake. In some specific embodiments, it is expected that
the
(-)-beloxepin compositions described herein will be useful to treat all of the
various diseases
that respond to treatment with other NRI agents, including, by way of example
and not
limitation, atomoxetine, reboxetine, maprotiline, and nortriptyline. Diseases
and disorders
known to be mediated, at least in part, by dysregulated NE reuptake, and that
are known to
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respond to treatment with NRI compounds, and that are expected to be treatable
with the
(-)-beloxepin compositions described herein, include, but are not limited to,
urinary disorders,
including urinary incontinence; mood disorders such as depression and seasonal
affective
disorder (SAD); cognitive disorders such as dementia; psychotic disorders such
as
schizophrenia and mania; anxiety disorders; personality disorders such as
ADHD; eating
disorders such as anorexia nervosa and bulimia nervosa; chemical dependencies
resulting
from addictions to drugs or substances of abuse such as addictions to
nicotine, alcohol,
cocaine, heroin, phenobarbital and benzodiazepines; withdrawal syndromes;
endocrine
disorders such as hyperprolactinaemia; impulse disorders such as
trichotillomania and
kleptomania; tic disorders such as Tourette's syndrome; gastrointestinal tract
disorders such
as irritable bowel syndrome (IBS), ileus, gastroparesis, peptic ulcer,
gastroesophageal reflux
disease (GORD, or its synonym GERD), flatulence and other functional bowel
disorders such
as dyspepsia (e.g., non-ulcerative dyspepsia (NUD)) and non-cardiac chest pain
(NCCP);
vascular disorders including vasospasms such as in the cerebral vasculature;
and
miscellaneous other disorders, including Parkinson's disease, shock and
hypertension, sexual
dysfunction, pre-menstrual syndrome and fibromyalgia syndrome.
[0113] One important class of diseases or disorders known to be responsive to
treatment with
NRIs is mental disease. Specific examples of such mental diseases or disorders
include, but
are not limited to, the various mental diseases and indications classified in
the Diagnostic and
Statistic Manual of Mental Disorders IV (Text Revision 2000; referred to
hereinafter as
"DSM-IV") as mood disorders (such as, for example, depression), anxiety
disorders (such as,
for example OCD), eating disorders, (such as, for example, anorexia nervosa
and bulimia
nervosa), impulse disorders (such as, for example, trichotillomania), sleep
disorders (such as,
for example, insomnia related to opioid withdrawal), personality disorders
(such as, for
example, ADHD), and somatoform disorders (such as certain types of pain). In
some
embodiments, the (-)-compositions described herein are used to treat such mood
disorders.
[0114] Pain is also thought to be mediated at least in part by NE reuptake.
Pain is generally
understood to refer to the perception or condition of unpleasant sensory or
emotional
experience, which may or may not be associated with actual damage to tissues.
It is generally
understood to include two broad categories, acute and chronic (see, e.g.,
Buschmann et at.,
(2002) "Analgesics," Wiley VCH, Verlag GMbH & Co. KgaA, Weinheim; Jain, 2000,
"Emerging Drugs" 5(2):241 257), and can be of either nociceptive origin (for
example
somatic or visceral) or non-nociceptive origin (for example neuropathic or
sympathetic).
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Acute pain generally includes nociceptive pain arising from strains/sprains,
bums, myocardial
infarction, acute pancreatitis, surgery, trauma and cancer. Chronic pain
generally includes
nociceptive pain, including, but not limited to, inflammatory pain such as
that associated with
IBS or rheumatoid arthritis, pain associated with cancer and pain associated
with
osteoarthritis; and non-nociceptive pain, including, but not limited to,
neuropathic pain (for
example post-herpetic neuralgia, trigeminal neuralgia, focal peripheral nerve
injury,
anesthesia clolorosa), central pain (for example, post-stroke pain, pain due
to spinal cord
injury or pain associated with multiple sclerosis), and peripheral neuropathy
(for example,
diabetic neuropathy, inherited neuropathy or other acquired neuropathies).
[0115] Data presented in the Examples section confirms that (-)-beloxepin is
effective at
treating pain in a rodent model of neuropathic pain. Based upon this animal
data, it is
expected that the (-)-beloxepin compositions described herein will be useful
in treating
various different pain syndromes, including chronic pain of nociceptive
origin, such as, for
example, inflammatory pain, and chronic pain of non-nociceptive origin, such
as, for
example, neuropathic pain. Accordingly, in some embodiments, the (-)-beloxepin
compositions described herein are used to treat pain, including the various
types pain
discussed above. It is also expected that the (-)-beloxepin compositions
described herein will
also be useful for blocking the onset of pain. In some embodiments, such
compositions
comprise beloxepin that is enriched in the (-) enantiomer. In some
embodiments, such
compositions comprise substantially enantiomerically pure (-)-beloxepin. In
some
embodiments, such compositions comprise enantiomerically pure (-)-beloxepin.
[0116] The therapy can be applied following the onset of pain and/or one or
more of its
symptoms, or prophylactically to avoid or delay its onset.
[0117] When used to treat various diseases or disorders discussed herein, the
(-)-beloxepin
composition will generally be administered in amounts effective to treat the
particular disease
or disorder. As will be recognized by skilled artisans, what is understood to
be
"therapeutically effective" and providing therapeutic benefit oftentimes
depends upon the
specific disease or disorder being treating. Skilled artisans will be able to
ascertain a
therapeutically effective amount based upon long established criteria for the
particular
indication.
[0118] In general, a "therapeutically effective" amount of a composition is an
amount that
eradicates or ameliorates the underlying disease or indication being treated
and/or that
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eradicates or ameliorates one or more of the symptoms associated with the
underlying
disorder such that the patient reports an improvement in feeling or condition,
not
withstanding that the patient may still be afflicted with the underlying
disease or indication.
Therapeutic benefits also includes halting or slowing the progression of the
disease or
indication, regardless of whether improvement is realized.
[0119] In the context of depression, a therapeutically effective amount is an
amount of
composition that eradicates or ameliorates the depression or the symptoms
thereof, including,
but not limited to, changes in mood, feeling of intense sadness, despair,
mental slowing, loss
of concentration, pessimistic worry, agitation, self-deprecation, insomnia,
anorexia, weight
loss, decreased energy and libido, and hormonal circadian rhythms.
[0120] In the context of anxiety disorder, a therapeutically effective amount
is an amount of
composition that eradicates or ameliorates the anxiety disorder or one of the
symptoms
thereof including, but are not limited to, a fear of losing control of one's
own actions, a sense
of terror arising from no apparent reason, a dread of catastrophe, uneasiness,
nervousness,
nagging uncertainty about future events, headaches, fatigue, and sub-acute
autonomic
symptoms.
[0121] In the context of pain, a therapeutically effective amount is an amount
of composition
that eradicates or ameliorates the pain or the symptoms thereof, including,
but not limited to,
shooting sensations, burning sensations, electrical sensations, aching,
discomfort, soreness,
tightness, stiffness, sleeplessness, numbness, and weakness. An effective
amount may also
be an amount of a composition that blocks the onset of pain or the symptoms
thereof. Thus,
the composition may be administered therapeutically after the onset of
sensation of pain or
one or more of its symptoms, and/or prophylactically prior to the onset of
sensation of pain or
one or more of its symptoms. Is some embodiments, the composition may be
administered in
response to the sensation of pain or one or more of its symptoms and
prophylactically
thereafter to avoid its recurrence
[0122] As described in more detail in Example 2, (+)-beloxepin binds to and
antagonizes the
5HT2A, 5HT2B and 5HT2c receptor subtypes. Antagonists of the 5HT2 receptors
are useful for
treating a variety of different diseases and disorders, mediated at least in
party by dysfunction
of 5-HT uptake, including but not limited to the following: neurological
conditions, including
sleep disorders (including disturbances of Circadian rhythm, dyssomnia,
insomnia, sleep
apnea and narcolepsy); psychotic disorders such as schizophrenia, depression,
anxiety, panic
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disorder, obsessive compulsive disorder, pain; eating disorders (anorexia,
anorexia nervosa
and anorexia bulimia), mood disorders (including social phobia, vascular
dementia with
depressed mood), extrapyramidal symptoms associated with the administration of
neuroleptic
agents; lowering of intraocular pressure and hence in treating glaucoma,
treatment of
menopausal symptoms, in particular, hot flushes; cardiovascular diseases;
disorders of the GI
tract, especially disorders involving altered mobility, including irritable
bowel syndrome;
disorders of gastric motility, dyspepsia, GERD, tachygastria, pain (e.g.
migraine/neurogenic
pain); benign prostatic hyperplasia, hypertension, priapism, asthma,
obstructive airway
disease, incontinence, bladder dysfunction, disorders of the uterus
(dysmenorrhea, pre term
labor, post partum remodeling, endometriosis, and fibrosis); pulmonary
hypertension;
epilepsy, Alzheimer's disease, cognitive disorders including dementia,
amnestic and
cognitive disorders; disorders associated with spinal trauma and/or head
injury such as
hydrocephalus. The compositions and methods disclosed herein are also useful
as memory
and/or cognition enhancers in healthy humans.
[0123] The ability of racemic ( )-beloxepin to cross the blood-brain barrier
has been
established in the literature (beloxepin has a reported logBB of 0.82; Kelder
et at., 1999,
Pharm. Res. 16:1514). Accordingly, the (+)-beloxepin compositions described
herein are
expected to be useful to treat any disease and/or disorder mediated, at least
in part, by
dysregulation of the 5HTz receptor, e.g., 5HTz receptor antagonism generally,
and 5HT2A,
5HT2B and/or 5HT2c receptor antagonism specifically. In some specific
embodiments, it is
expected that the (+)-beloxepin compositions described herein will be useful
to treat many
different diseases that respond to treatment with other 5HTz antagonists,
including, by way of
example and not limitation, neurological conditions, including sleep disorders
(including
disturbances of Circadian rhythm, dyssomnia, insomnia, sleep apnea and
narcolepsy);
psychotic disorders such as schizophrenia, depression, anxiety, panic
disorder, obsessive
compulsive disorder, pain; eating disorders (anorexia, anorexia nervosa and
anorexia
bulimia), mood disorders (including social phobia, vascular dementia with
depressed mood),
extrapyramidal symptoms associated with the administration of neuroleptic
agents; lowering
of intraocular pressure and hence in treating glaucoma, treatment of
menopausal symptoms,
in particular, hot flushes; cardiovascular diseases; disorders of the GI
tract, especially
disorders involving altered mobility, including irritable bowel syndrome;
disorders of gastric
motility, dyspepsia, GERD, tachygastria, pain (e.g. migraine/neurogenic pain);
benign
prostatic hyperplasia, hypertension, priapism, asthma, obstructive airway
disease,
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incontinence, bladder dysfunction, disorders of the uterus (dysmenorrhea, pre-
term labor,
post partum remodelling, endometriosis, and fibrosis); pulmonary hypertension;
epilepsy,
Alzheimer's disease, cognitive disorders including dementia, amnestic and
cognitive
disorders; disorders associated with spinal trauma and/or head injury such as
hydrocephalus.
The compositions and methods disclosed herein are also useful as memory and/or
cognition
enhancers in healthy humans.
[0124] Animal data presented herein establishes that (+)-beloxepin is also
useful for treating
pain. Pain is generally understood to refer to the perception or condition of
unpleasant
sensory or emotional experience, which may or may not be associated with
actual damage to
tissues. It is generally understood to include two broad categories; acute and
chronic (see,
e.g., Buschmann et at., 2002, "Analgesics," Wiley VCH, Verlag GMbH & Co. KgaA,
Weinheim; Jain, 2000, Expert Opinion on Emerging Drugs 5(2):241-257), and can
be of
nociceptive origin (for example somatic or visceral) or non-nociceptive origin
(for example
neuropathic or sympathetic). Acute pain generally includes nociceptive pain
arising from
strains/sprains, bums, myocardial infarction, acute pancreatitis, surgery,
trauma and cancer.
Chronic pain generally includes nociceptive pain, including, but not limited
to, inflammatory
pain such as that associated with IBS or rheumatoid arthritis, pain associated
with cancer and
pain associated with osteoarthritis; and non-nociceptive pain, including, but
not limited to,
neuropathic pain such as post-herpetic neuralgia, trigeminal neuralgia, focal
peripheral nerve
injury, anesthesia clolorosa, central pain (for example, post-stroke pain,
pain due to spinal
cord injury or pain associated with multiple sclerosis), and peripheral
neuropathy (for
example, diabetic neuropathy, inherited neuropathy or other acquired
neuropathies).
[0125] Data presented in the Examples section confirms that (+)-beloxepin is
effective at
treating pain in a rodent model of pain. Based upon this animal data, it is
expected that the
(+)-beloxepin compositions described herein will be useful in treating various
different pain
syndromes, including chronic pain of nociceptive origin, such as, for example,
inflammatory
pain, and chronic pain of non-nociceptive origin, such as, for example,
neuropathic pain.
Accordingly, in some embodiments, the (+)-beloxepin compositions described
herein are
used to treat pain, including the various types pain discussed above. It is
also expected that
the (+)-beloxepin compositions disclosed herein will be useful for blocking
the onset of pain.
In some embodiments, the (+)-beloxepin composition comprises beloxepin that is
enriched in
the (+) enantiomer. In some embodiments, such compositions comprise
substantially
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enantiomerically pure (+)-beloxepin. In some embodiments, such compositions
comprise
enantiomerically pure (+)-beloxepin.
[0126] When used to treat various diseases or disorders discussed herein, the
(+)-beloxepin
composition will generally be administered in amounts effective to treat the
particular disease
or disorder. As will be recognized by skilled artisans, what is understood to
be
"therapeutically effective" and providing therapeutic benefit oftentimes
depends upon the
specific disease or disorder being treating. Skilled artisans will be able to
ascertain a
therapeutically effective amount based upon long established criteria for the
particular
indication.
[0127] In general, a "therapeutically effective" amount of a composition is an
amount that
eradicates or ameliorates the underlying disease or indication being treated
and/or that
eradicates or ameliorates one or more of the symptoms associated with the
underlying
disorder such that the patient reports an improvement in feeling or condition,
not
withstanding that the patient may still be afflicted with the underlying
disease or indication.
Therapeutic benefits also includes halting or slowing the progression of the
disease or
indication, regardless of whether improvement is realized, including those
diseases,
conditions, and indications disclosed above.
[0128] In the context of pain, a therapeutically effective amount is an amount
of composition
that eradicates or ameliorates the pain or the symptoms thereof, including,
but not limited to,
shooting sensations, burning sensations, electrical sensations, aching,
discomfort, soreness,
tightness, stiffness, sleeplessness, numbness, and weakness. An effective
amount may also
be an amount of a composition that blocks the onset of pain or the symptoms
thereof. An
effective amount may also be an amount of a composition comprising (+)-
beloxepin that
blocks the onset of pain or the symptoms thereof.
[0129] The therapy can be applied following the onset of pain and/or one more
of its
symptoms, or prophylactically to avoid or delay its onset.
8.4 Combination Therapies
[0130] Beloxepin, (-)-beloxepin, (+)-beloxepin, and/or their analogs can be
used alone, or in
combination with, or adjunctively to, other therapeutic agents to treat pain.
[0131] Accordingly, beloxepin and/or its analogs can be combined with other
analgesics,
including but not limited to, cannabinoids and opioids. A number of
cannabinoids are
available that may be suitable for use in combination therapy, including, but
not limited to, a
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cannabinoid that is selected from a A9-tetrahydrocannabinol and cannabidiol,
and mixtures
thereof.
[0132] It is also expected that the (-)-beloxepin compositions described
herein will be useful
in combination therapy for the treatment of pain. Accordingly, the (-)-
beloxepin
compositions described herein can be combined with other analgesics, including
but not
limited to, cannabinoids and opioids. A number of cannabinoids are available
that may be
suitable for use in combination therapy, including, but not limited to, a
cannabinoid that is
selected from a A9-tetrahydrocannabinol and cannabidiol, and mixtures thereof.
[0133] It is also expected that the (+)-beloxepin compositions described
herein will be useful
in combination therapy for the treatment of pain. Accordingly, the (+)-
beloxepin
compositions can be combined with other analgesics, including but not limited
to,
cannabinoids and opioids. A number of cannabinoids are available that may be
suitable for
use in combination therapy, including, but not limited to, a cannabinoid that
is selected from
a A9-tetrahydrocannabinol and cannabidiol, and mixtures thereof.
[0134] Alternatively, beloxepin (-)-beloxepin, (+)-beloxepin, and/or their
analogs may be
used in combination with at least one opioid. A wide variety of opioids are
available that
may be suitable for use in combination therapy to treat pain. As such, the
combination
therapy may involve an opioid that is selected from, but not limited to,
alfentanil,
allylprodine, alphaprodine, anileridine, benzyl-morphine, bezitramide,
buprenorphine,
butorphanol, clonitazene, codeine, cyclazocine, desomorphine, dextromoramide,
dezocine,
diampromide, diamorphone, dihydrocodeine, dihydromorphine, dimenoxadol,
dimepheptanol, dimethylthiambutene, dioaphetylbutyrate, dipipanone,
eptazocine,
ethoheptazine, ethylmethylthiambutene, ethylmorphine, etonitazene, fentanyl,
heroin,
hydrocodone, hydromorphone, hydroxypethidine, isomethadone, ketobemidone,
levallorphan, levorphanol, levophenacylmorphan, lofentanil, loperamide,
meperidine
(pethidine), meptazinol, metazocine, methadone, metopon, morphine, myrophine,
nalbuphine, narceine, nicomorphine, norlevorphanol, normethadone, nalorphine,
normorphine, norpinanone, opium, oxycodone, oxymorphone, papaveretum,
pentazocine,
phenadoxone, phenomorphan, phanazocine, phenoperidine, piminodine,
piritramide,
propheptazine, promedol, properidine, propiram, propoxyphene, sulfentanil,
tilidine,
tramadol, diastereoisomers thereof, pharmaceutically acceptable salts thereof,
complexes
thereof, and mixtures thereof. In some embodiments, the opioid is selected
from morphine,
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codeine, oxycodone, hydrocodone, dihydrocodeine, propoxyphene, fentanyl,
tramadol, and
mixtures thereof.
[0135] The opioid component of the combination therapy may further include one
or more
other active ingredients that may be conventionally employed in analgesic
and/or
cough-cold-antitussive combination products. Such conventional ingredients
include, for
example, aspirin, acetaminophen, phenylpropanolamine, phenylephrine,
chlorpheniramine,
caffeine, and/or guaifenesin. Typical or conventional ingredients that may be
included in the
opioid component are described, for example, in the Physicians' Desk
Reference, 1999, the
disclosure of which is hereby incorporated herein by reference, in its
entirety.
[0136] The opioid component may further include one or more compounds that may
be
designed to enhance the analgesic potency of the opioid and/or to reduce
analgesic tolerance
development. Such compounds include, for example, dextromethorphan or other
NMDA
antagonists (Mao et at., 1996, Pain 67:361), L-364,718 and other CCK
antagonists (Dourish
et at., 1988, Eur. J. Pharmacol 147:469), NOS inhibitors (Bhargava et at.,
1996,
Neuropeptides 30:2), PKC inhibitors (Bilsky et at., 1996, J. Pharmacol. Exp.
Ther. 277:484),
and dynorphin antagonists or antisera (Nichols et at., 1997, Pain 69:317). The
disclosures of
each of the foregoing documents are hereby incorporated herein by reference,
in their
entireties.
[0137] Alternatively, beloxepin, (-)-beloxepin, (+)-beloxepin, and/or their
analogs may be
used with at least one non opioid analgesic, such as for example, diclofenac,
a COX2
inhibitor, aspirin, acetaminophen, ibuprophen, naproxen, and the like, and
mixtures thereof.
[0138] Other agents that may be used in combination with the beloxepin, (-)-
beloxepin,
(+)-beloxepin, and/or their analogs, include anti-inflammatories (NSAIDS).
Specific
examples of suitable anti-inflammatories include, but are not limited to,
corticosteroids,
aminoarylcarboxylic acid derivatives such as, but not limited to, etofenamate,
meclofenamic
acid, mefanamic acid, niflumic acid; arylacetic acid derivatives such as, but
not limited to,
acemetacin, amfenac cinmetacin, clopirac, diclofenac, fenclofenac, fenclorac,
fenclozic acid,
fentiazac, glucametacin, isozepac, lonazolac, metiazinic acid, oxametacine,
proglumetacin,
sulindac, tiaramide and tolmetin; arylbutyric acid derivatives such as, but
not limited to,
butibufen and fenbufen; arylcarboxylic acids such as, but not limited to,
clidanac, ketorolac
and tinoridine; arylpropionic acid derivatives such as, but not limited to,
bucloxic acid,
carprofen, fenoprofen, flunoxaprofen, ibuprofen, ibuproxam, oxaprozin,
piketoprofen,
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pirprofen, pranoprofen, protizinic acid and tiaprofenic add; pyrazoles such
as, but not limited
to, mepirizole; pyrazolones such as, but not limited to, clofezone, feprazone,
mofebutazone,
oxyphenbutazone, phenylbutazone, phenyl pyrazolidininones, suxibuzone and
thiazolinobutazone; salicylic acid derivatives such as, but not limited to,
bromosaligenin,
fendosal, glycol salicylate, mesalamine, 1-naphthyl salicylate, olsalazine and
sulfasalazine;
thiazinecarboxamides such as, but not limited to, droxicam, isoxicam and
piroxicam; and
other anti-inflammatory agents such as, but not limited to, e-acetamidocaproic
acid, s-
adenosylmethionine, 3-amino-4-hydroxybutyric acid, amixetrine, bendazac,
bucolome,
carbazones, difenpiramide, ditazol, guaiazulene, heterocyclic aminoalkyl
esters of
mycophenolic acid and derivatives, nabumetone, nimesulide, orgotein,
oxaceprol, oxazole
derivatives, paranyline, pifoxime, 2-substituted-4,6-di-tertiary-butyl-s-
hydroxy-1,3-
pyrimidines, proquazone and tenidap.
[0139] beloxepin, (-)-beloxepin, (+)-beloxepin, and/or their analogs, can also
be used in
combination with each other. Thus, in some embodiments, the combination
therapy involves
administration of two or more beloxepin analogs, or beloxepin and one or more
beloxepin
analogs.
[0140] Compounds that inhibit NE reuptake have been used in combination with
other
therapies to treat various indications. For example, amitryptiline has been
used in
combination with chlordiazepoxide to treat anxiety disorder and major
depressive disorder,
and has been used in combination with perphenazine to treat anxiety disorder,
schizophrenia
and major depressive disorder. Nortryptiline has been used in combination with
budenoside
to treat asthma. It is expected that the (-)-beloxepin compositions described
herein will also
be useful in combination therapies.
[0141] When used in combination therapy, the (-)-beloxepin compositions
described herein
may be used in combination with, or as an adjunct to, other agents. When the (-
)-beloxepin
compositions described herein are used in combination with other agents, the
two agents may
be administered in a single pharmaceutical compositor or they may be
administered in
separate pharmaceutical compositions. The two components may be administered
by the
same route of administration or by a different route of administration. The
two components
also may be administered simultaneously with each other or sequentially. Thus
each
component of the combination therapy may be administered separately but
sufficiently
closely in time to the administration of the other component as to provide the
desired effect.
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[0142] While combination therapy involving the (-)-beloxepin compositions
described herein
is useful in many contexts, the other agent used with the (-)-beloxepin
composition will
depend on the specific disease or indication being treated. The skilled
artisan will be able to
ascertain what other agent to use in combination with the (-)-beloxepin
compositions based
upon long established criteria for the particular indication.
[0143] While not intending to be bound by any theory of operation, the
combination therapy
may include the administration of the (-)-beloxepin compositions described
herein with other
agents known to inhibit reuptake of NE. Alternatively, the combination therapy
may include
the administration of the (-)-beloxepin compositions with agents which do not
inhibit the
reuptake of NE. In some embodiments, the (-)-beloxepin compositions are
administered in
combination with compounds that inhibit other monoamine transporters, such as
the 5HT
transporter. In some specific embodiments, the (-)-beloxepin compositions are
administered
in combination with a selective serotonin reuptake inhibitor (SSRI), such as,
but not limited
to, fluoxetine, paroxetine, fluvoxamine, citaprolam, or sertraline, to treat
depression.
Combination therapy for the treatment of depression may also involve a
monoamine oxidase
inhibitor (MAOIs), such as, but not limited to, tranylcypromine, phenelzine,
or isocarboxazid.
[0144] Compounds that antagonize 5HT2 receptors have been used in combination
with
other therapies to treat various indications. It is expected that the (+)-
beloxepin compositions
described herein will also be useful in combination therapies.
[0145] When used in combination therapy, the (+)-beloxepin compositions may be
used in
combination with, or as an adjunct to, other agents. When the (+)-beloxepin
compositions
are used in combination with other agents, the two agents may be administered
in a single
pharmaceutical compositor or they may be administered in separate
pharmaceutical
compositions. The two components may be administered by the same route of
administration
or by a different route of administration. The two components also may be
administered
simultaneously with each other or sequentially. Thus each component of the
combination
therapy may be administered separately but sufficiently closely in time to the
administration
of the other component as to provide the desired effect.
[0146] While combination therapy involving the (+)-beloxepin compositions
described
herein is useful in many contexts, the other agent used with the (+)-beloxepin
compositions
will depend on the specific disease or indication being treated. The skilled
artisan will be
able to ascertain what other agent to use in combination with the (+)-
beloxepin compositions
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based upon long established criteria for the particular indication. While not
intending to be
bound by any theory of operation, the combination therapy may include the
administration of
the (+)-beloxepin compositions described herein with other agents known to
antagonize
5HT2 receptors generally, and 5HT2A, 5HT2B and/or 5HT2c receptors
specifically.
Alternatively, the combination therapy may include the administration of the
(+)-beloxepin
compositions described herein with agents which do not antagonize 5HT2
receptors.
8.5 Additional Properties of Beloxepin
[0147] As indicated in Example 3, an initial, screening study suggested that
beloxepin
inhibits the polymorphic cytochrome P450 isoenzyme CYP2D6 (IC50 = 536 nM). A
subsequent, more definitive analysis in which CYP2D6 inhibition by beloxepin
was
measured human hepatic microsomes using dextromethorphan as the model. There,
beloxepin caused direct inhibition of CYP2D6 with an IC50 value of only 31.7
M (Figure
15), indicating that, CYP inhibition would therefore be negligible for
beloxepin. Cytochrome
P450 enzymes play important roles in drug metabolism. For example, many
tricyclic
antidepressants used off-label to treat pain are metabolized by CYP2D6. Use of
inhibitors of
this enzyme in combination therapy regimens can therefore dramatically
increase their levels.
Co-administration of CYP2D6 inhibitors with substrates of CYP2D6 can also
prolong the QT
interval, leading to arrythmias.
[0148] Certain prodrugs are acted upon by CYP2D6 to release the active drug.
CYP2D6
inhibitors would likely reduce the efficacy of such CYP2D6-activated drugs. As
a specific
example, clinical evidence suggest that CYP2D6-activated prodrugs such as
codeine and
tramadol are less effective in patients who are genetically deficient in
CYP2D6 or in patients
receiving potent CYP2D6 inhibitors.
[0149] Cytochrome P4502D6 (CYP2D6) is a polymorphic member of the P450
superfamily,
which is absent in 5-9% of the Caucasian population, resulting in a deficiency
in drug
oxidation known as debrisoquine/sparteine polymorphism. Metabolism by
polymorphic
isoenzymes such as CYP2D6 can be problematic in drug development because of
the wide
variation in the pharmacokinetics of the patient population. CYP2D6
metabolises many
currently used drugs, which include (3-blockers, antidepressants, and
neuroleptics (Bertz and
Granneman, 1997, Clin. Pharmokinet. 32(3):210-58). Polymorphisms of 2D6 have
been
associated with a reduced capacity to dispose important drugs; this leads to
undesirable
clinical consequences (Ingelman-Sundberg et at., 1999, Trends. Pharmacol. Sci.
20(8):342-
349). The impact of human P450 polymorphisms on drug treatment in poor
metabolizers is
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indicated in Table 2 below (Ingelman-Sundberg et at., 1999, Trends. Pharmacol.
Sci.
20(8):342-349).
Table 2
Impact of human P450 polymorphisms on drug treatment in poor metabolizers
Polymorphic enzyme Decreased clearance Adverse effects Reduced prodrug
activation
CYP 2C9 S-Warfarin Bleeding Losartan
PHenytoin Ataxia
Losartan
Tolbutamide Hypoglycaemia
NSAIDs GI bleeding
CYP 2C19 Omeprazole Proguanil
Diazepam Sedation
CP2D6 Tricyclic Cardiotoxicity Tramadol
antidepressants Codeine
Haloperidol Parkinsonism Ethylmorphine
Anti-arrhythmic drugs Arrhythmias
Perphenazine
Perhexiline Neuropathy
SSRIs Nausea
Zuclopenthixol
S-Mianserin
Tolterodine
Abbreviations: NSAIDs, nonsteroidal anti-inflammatory drugs; SSRIs, selective
serotonin reuptake
inhibitors
[0150] Thus, in view of the above and the data of Example 3, skilled artisans
will appreciate
that in the various combination therapies discussed herein, dosages may need
to be adjusted
when beloxepin and/or its analogs are administered in combination with, or
adjunctively to,
drugs that are either metabolized by or activated by, CYP2D6.
[0151] As indicated above, preliminary screening assays for inhibition of cDNA-
expressed
human CYP450 isozymes by beloxepin at 10 M, suggested extensive inhibition of
CYP2D6
(97%). The potential inhibition of CYP2D6 was re-evaluated using
dextromethorphan as the
model substrate, and measuring inhibition of CYP2D6 by beloxepin in human
hepatic
microsomes. In these definitive studies, beloxepin caused direct inhibition of
CYP2D6 with
an IC50 value of 31.7 M (Figure 15). At anticipated therapeutic plasma
concentrations, CYP
inhibition would therefore be negligible for beloxepin. This suggests that
beloxepin has little
potential for drug-drug interactions.
[0152] As evidenced by Example 4, (-)-beloxepin does not appreciably inhibit
the
polymorphic cytochrome P450 isoenzyme CYP2D6 (IC50 = 4370 nM). Many drugs that
would be useful in compositions described herein are metabolized or activated
by CYP2D6.
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Since (-)-beloxepin does not appreciably inhibit this P450 isoenzyme,
combination therapy
with (-)-beloxepin can be applied without having to alter dosages of drugs
metabolized by or
activated by CPY2D6.
[0153] As indicated in Example 3, (+)-beloxepin is an inhibitor of the
polymorphic
cytochrome P450 isoenzyme CYP2D6 (IC50 = 236 nM), that is approximately 18-
fold more
active (as an inhibitor of CYP2D6) than the (-) enantiomer in this assay.
[0154] Thus, skilled artisans will appreciate that in the various combination
therapies
discussed herein, dosages may need to be adjusted when the (+)-beloxepin
compositions are
administered in combination with, or adjunctively to, drugs that are either
metabolized by or
activated by, CYP2D6.
8.6 Formulations And Administration
[0155] Beloxepin, (-)-beloxepin, (+)-beloxepin, and/or their analogs (or salts
thereof) may be
combined with a pharmaceutical carrier selected on the basis of the chosen
route of
administration and standard pharmaceutical practice as described, for example,
in
Remington's Pharmaceutical Sciences, 2005, the disclosure of which is hereby
incorporated
herein by reference, in its entirety. The relative proportions of active
ingredient and carrier
may be determined, for example, by the solubility and chemical nature of the
compounds,
chosen route of administration and standard pharmaceutical practice.
[0156] The beloxepin, (-)-beloxepin, (+)-beloxepin, and/or their analogs (or
salts thereof)
compositions described herein, may be administered to a mammalian subject in a
variety of
forms adapted to the chosen route of administration, e.g., orally or
parenterally. Parenteral
administration in this respect includes administration by the following
routes: intravenous,
intramuscular, subcutaneous, intraocular, intrasynovial, transepithelial
including transdermal,
ophthalmic, sublingual and buccal; topically including ophthalmic, dermal,
ocular, rectal and
nasal inhalation via insufflation, aerosol and rectal systemic.
[0157] Compositions comprising beloxepin, (-)-beloxepin, (+)-beloxepin, and/or
their
analogs, (and salts thereof) may be formulated for oral administration, for
example, with an
inert diluent or with an assimilable edible carrier, or it may be enclosed in
hard or soft shell
gelatin capsules, or it may be compressed into tablets, or it may be
incorporated directly with
the food of the diet. For oral therapeutic administration, the active compound
may be
incorporated with excipient and used in the form of ingestible tablets, buccal
tablets, troches,
capsules, elixirs, suspensions, syrups, wafers, and the like. The amount of
active
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compound(s) in such therapeutically useful compositions is preferably such
that a suitable
dosage will be obtained. Preferred compositions or preparations may be
prepared so that an
oral dosage unit form contains from about 0.1 to about 1000 mg of each
beloxepin
enantiomer (and all combinations and subcombinations of ranges and specific
concentrations
therein).
[0158] The tablets, troches, pills, capsules and the like may also contain one
or more of the
following: a binder such as gum tragacanth, acacia, corn starch or gelatin; an
excipient, such
as dicalcium phosphate; a disintegrating agent such as corn starch, potato
starch, alginic acid
and the like; a lubricant such as magnesium stearate; a sweetening agent such
as sucrose,
lactose or saccharin; or a flavoring agent such as peppermint, oil of
wintergreen or cherry
flavoring. When the dosage unit form is a capsule, it may contain, in addition
to materials of
the above type, a liquid carrier. Various other materials may be present as
coating, for
instance, tablets, pills, or capsules may be coated with shellac, sugar or
both. A syrup or
elixir may contain the active compound, sucrose as a sweetening agent, methyl
and
propylparabens as preservatives, a dye and flavoring, such as cherry or orange
flavor. Of
course, any material used in preparing any dosage unit form is preferably
pharmaceutically
pure and substantially non toxic in the amounts employed.
[0159] The compositions may also be formulated for parental or intraperitoneal
administration. Solutions of the beloxepin enantiomers as free bases or
pharmacologically
acceptable salts can be prepared in water suitably mixed with a surfactant,
such as
hydroxypropylcellulose. A dispersion can also be prepared in glycerol, liquid
polyethylene
glycols, and mixtures thereof and in oils. Under ordinary conditions of
storage and use, these
preparations may contain a preservative to prevent the growth of
microorganisms.
[0160] Compositions suitable for administration by injection typically
include, for example,
sterile aqueous solutions or dispersions and sterile powders for the
extemporaneous
preparation of sterile injectable solutions or dispersions. In all cases, the
form is preferably
sterile and fluid to provide easy syringability. It is preferably stable under
the conditions of
manufacture and storage and is preferably preserved against the contaminating
action of
microorganisms such as bacteria and fungi. The carrier may be a solvent or
dispersion
medium containing, for example, water, ethanol, polyol (for example, glycerol,
propylene
glycol, liquid polyethylene glycol and the like), suitable mixtures thereof,
and vegetable oils.
The proper fluidity can be maintained, for example, by the use of a coating,
such as lecithin,
by the maintenance of the required particle size in the case of a dispersion,
and by the use of
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surfactants. The prevention of the action of microorganisms may be achieved by
various
antibacterial and antifungal agents, for example, parabens, chlorobutanol,
phenol, sorbic acid,
thimerosal and the like. In many cases, it will be preferable to include
isotonic agents, for
example, sugars or sodium chloride. Prolonged absorption of the injectable
compositions
may be achieved by the use of agents delaying absorption, for example,
aluminum
monostearate and gelatin.
[0161] Sterile injectable solutions may be prepared by incorporating the
active compounds in
the required amounts, in the appropriate solvent, with various of the other
ingredients
enumerated above, as required, followed by filtered sterilization. Generally,
dispersions may
be prepared by incorporating the sterilized active ingredient into a sterile
vehicle which
contains the basic dispersion medium and the required other ingredients from
those
enumerated above. In the case of sterile powders for the preparation of
sterile injectable
solutions, the preferred methods of preparation may include vacuum drying and
the freeze
drying technique that yields a powder of the active ingredient, plus any
additional desired
ingredient from the previously sterile filtered solution thereof.
8.7 Effective Dosages
[0162] Beloxepin, (-)-beloxepin, (+)-beloxepin, and/or their analogs (or salts
thereof), will
generally be administered in a therapeutically effective amount, as described
herein. The
quantity of beloxepin and/or beloxepin analog compounds will depend upon a
variety of
factors, including, for example, the particular pain indication or syndrome
being treated, the
mode of administration, whether the desired benefit is prophylactic or
therapeutic, the
severity of the pain indication or syndrome being treated, the age and weight
of the patient,
and the bioavailability of the beloxepin, (-)-beloxepin, (+)-beloxepin, and/or
their analogs (or
salts thereof) administered. Determination of an effective dosage is well
within the
capabilities of those skilled in the art.
[0163] Dosage amounts will typically be in the range of from about 0.0001 or
0.001 or 0.01
mg/kg/day total active compound(s) to about 0.1 or 1.0 or 2.0 or 2.5 or 5.0 or
10.0 or 20.0 or
25.0 or 50.0 or 75.0 or 100 mg/kg/day total active compound(s), with an
expected dose of
about 5 mg/kg/day to about 1500 mg/kg/day total active compound(s), but may be
higher or
lower, depending upon, among other factors, the factors mentioned above.
[0164] Dosage amount and interval may be adjusted individually to provide
plasma levels of
active compound(s), which are sufficient to maintain therapeutic or
prophylactic effect. As
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non-limiting examples, the compositions may be administered once per day or
multiple times
per day, depending upon, among other things, the mode of administration, the
specific
indication being treated and the judgment of the prescribing physician. In
cases of local
administration or selective uptake, such as local topical administration, the
effective local
concentration of active compounds and/or compositions may not be related to
plasma
concentration. Skilled artisans will be able to optimize effective local
dosages without undue
experimentation.
[0165] Initial dosages of the (-)-beloxepin compound and/or compositions
useful for the
treatment of pain can be estimated from in vivo data, such as the animal data
described in the
Examples section.
[0166] Initial dosages of the (+)-beloxepin compound and/or compositions
useful for the
treatment of pain can be estimated from in vivo data, such as the animal data
described in the
Examples section.
[0167] Based on the animal data described in the Examples section (e.g.
Examples 4-13), it is
expected that an effective dosage of beloxepin for the treatment of pain in
humans may be
obtained by administering a dose of beloxepin sufficient to achieve a plasma
concentration
similar to that achieved following the administration of 30 mg/kg, i.p. to
rats, or 60 mg/kg PO
to rats. As such, in some embodiments the effective dose of beloxepin for the
treatment of
pain is the dosage required to achieve the plasma concentration achieved when
30 mg/kg
beloxepin is administered i.p. to rats, or when 60 mg/kg beloxepin is
administered orally to
rats.
[0168] Based on the animal data described in Examples 4, 7, 18 and 13, it is
expected that an
effective dosage of (-)-beloxepin for the treatment of pain in humans may be
obtained by
administering a dose of (-)-beloxepin sufficient to achieve a plasma
concentration similar to
that achieved following the administration of 30 mg/kg, i.p. to rats. As such,
in some
embodiments the effective dose of (-)-beloxepin for the treatment of pain is
the dosage
required to achieve the plasma concentration achieved when 30 mg/kg (-)-
beloxepin is
administered i.p. to rats.
[0169] Based on these animal data, it is expected that oral doses of
beloxepin, (-)-beloxepin,
and (+)-beloxepin (Example 13), of between about 10 mg/day to about 20 or 25
or 30 or 35
or 40 or 45 or 50 or 60 or 70 or 80 or 90 or
95or100or200or500or750or1000or1500
mg/day will be effective in treating pain. Accordingly, some embodiments
involve the
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administration of an oral dosage of beloxepin that ranges from about 10 mg/day
to about 500
mg per dose, one or more times per day. It is expected that similar dosage
ranges of
beloxepin analogs will be effective.
[0170] In the context of combination therapy, the proper dosage of the
combined agents will
be readily ascertainable by a skilled artisan based on long established
criteria. By way of
general guidance, where a cannabinoid, opioid and/or other agent is used in
combination with
beloxepin, (-)-beloxepin, and (+)-beloxepin, the dosage will typically range
from about 0.01
to about 100 mg/kg/day of the cannabinoid, opioid and/or other active compound
and about
0.001 to about 100 mg/kg/day of beloxepin, (-)-beloxepin, or (+)-beloxepin,.
In certain
embodiments, the dosage may be about 0.1 to about 10 mg/kg/day of the
cannabinoid, opioid
and/or other active compound and about 0.01 to about 10 mg/kg/day of
beloxepin, and in
other embodiments, the daily dosage may be about 1.0 mg of the cannabinoid,
opioid and/or
other active compound and about 0.1 mg of beloxepin. Alternatively, when
beloxepin is
combined with a cannabinoid compound (e.g., A9-tetrahydrocannabinol or
cannabidiol), an
opioid compound (e.g., morphine) and/or an other agent and the combination is
administered
orally, the dosage may generally range from about 15 to about 200 mg of the
cannabinoid,
opioid and/or other agent, and about 0.1 to about 4 mg of beloxepin, (-)-
beloxepin, or
(+)-beloxepin. It is expected that similar dosage ranges will be effective for
combination
therapies with analogs of beloxepin, (-)-beloxepin, and/or (+)-beloxepin.
8.8 Kits
[0171] Beloxepin, (-)-beloxepin, (+)-beloxepin and/or their analogs, and/or
salts thereof, may
be assembled in the form of kits. In some embodiments, the kit provides the
compounds(s)
and reagents to prepare a composition for administration. The composition may
be in a dry
or lyophilized from, or in a solution, particularly a sterile solution. When
the composition is
in a dry form, the reagent may comprise a pharmaceutically acceptable diluent
for preparing a
liquid formulation. The kit may contain a device for administration or for
dispensing the
compositions, including, but not limited to, syringe, pipette, transdermal
patch or inhalant.
[0172] The kits may include other therapeutic agents for use in conjunction
with the
compositions described herein. In some embodiments, the therapeutic agents may
be
provided in a separate form, or mixed with the compositions described herein.
[0173] Kits can include appropriate instructions for preparation and
administration of the
composition, side effects of the compositions, and any other relevant
information. The
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instructions may be in any suitable format; including, but not limited to,
printed matter,
videotape, computer readable disk, or optical disk.
9. EXAMPLES
[0174] The following working examples, which are intended to be illustrative
and not
limiting, highlight various features of beloxepin and certain uses described
herein.
Example 1: Synthesis of ( )-Beloxepin and Isolation of
(-)-Beloxepin and (+)-Beloxepin
[0175] With reference to Scheme 1, reproduced below, beloxepin was
synthesized, and the
(-) and (+) enantiomers thereof were isolated, as follows.
CS2CO3,CUCI \
TDA, DM F
80 C, 24-48 hr / PPA O
OH OH 45-50% yield sulfolane a + ,,,0" HO \ 120 C
O 80%
TDA B C
0 O HO
NH2Me,TBTU HN
Br--/~-O TF 0 O DIES O O
4rD NaH/THF, 0 C 94% 93%
\ 78% / O / \ E F
NH NH
~
O
NaBH4 60" OH BH3 DMS OH BOC20 -N
MeO~ THE T OH
97% O / \ 862 o I / O / \ 100% 3
G H O
O
NH
1. Ms-Cl N O /
TEA, DCM HCl in Et20 2N HCl N
DCM Formaldehyde
2. DBU 91% I / / \ 50oC HO H
Toluene o
56% O O 66%
O
K L
/ /
N N
Chiral separation HO H HO H
O 0
M N
[0176] Preparation of 2-(2-(o-tolyloxx)phenyl)acetic acid (B): To a solution
of A (50.0 g,
232 mmol, 1.00 eq) in N,N-dimethylformamide (500 mL) under nitrogen and with
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mechanical stirring was added cesium carbonate (189 g, 581 mmol, 2.50 eq), o-
cresol (28.8
mL, 279 mmol, 1.20 eq), copper(I) chloride (12 g, 120 mmol, 0.5 eq) and
tris(3,6-
dioxaheptyl)amine (TDA) (37 mL, 120 mmol, 0.5 eq). The reaction was degassed
by
bubbling nitrogen through the stirring mixture for 10 minutes. The mixture was
then heated
at 80 C for 2 days under nitrogen. The reaction was cooled to room temperature
and diluted
with 1:1 diethyl ether/hexanes. While stirring, the mixture was carefully
acidified with 6M
HC1, then diluted with water and the layers were separated. The aqueous layer
was washed
with 1:1 diethyl ether/hexanes and all organics were combined and washed with
0.5M sodium
carbonate. The basic aqueous layers were combined, acidified with 6M HC1 and
the product
was extracted with diethyl ether. The organics were concentrated and purified
by a silica gel
plug using 2-5% isopropanol/hexane gradient to give 31.48 g yellow/green oil
(51% yield,
based on 1H NMR purity of 92%). 1H NMR (400 MHz, CDC13) 7.29 (dd, 1H), 7.23-
7.10 (m,
3H), 7.05 (m, 2H), 6.83 (dd, 1H), 6.63 (dd, 1H), 3.77 (s, 2H), 2.20 (s, 3H);
MS: (M-H)- _
241.1.
[0177] Preparation of 6-methyldibenzo[b,floxepin-10(11H)-one (C): A mixture of
B (60.7 g,
213 mmol, 1.00 eq, 85% purity), polyphosphoric acid (93 g, 852 mmol, 4.00 eq)
and
sulfolane (200 mL) was immersed in an oil bath at 120 C and heated for 90
minutes. Ice
water was added and the product was extracted with diethyl ether. The organic
layer was
washed with 0.5 M sodium carbonate, concentrated and purified by a silica gel
plug using a
1-4% ethyl acetate/hexanes gradient to give 41.4 g orange oil (80%**). **yield
based on
85% purity of starting material B and 92% purity of product C. 1H NMR (400
MHz, CDC13)
7.91 (m, I H), 7.44 (m, I H), 7.32 (m, I H), 7.25 (m, 2H), 7.19 (m, I H), 7.07
(m, I H), 4.10 (s,
2H), 2.57 (s, 3H)
[0178] Preparation of (4-Methyl-l l-oxo-10,11-dihydro-dibenzo[b,floxepin-10-
yl)-acetic
acid tert-butyl ester (D): To a mixture of 60% sodium hydride in mineral oil
(8.16 g, 204
mmol, 1.2 eq) in tetrahydrofuran (400 mL) cooled in a brine/water bath was
added dropwise
a solution of the ketone C (41.4 g, 170 mmol, 1.0 eq, 92% purity) in
tetrahydrofuran (200
mL). The mixture was stirred for an additional 10 minutes. The bromide was
added
dropwise over a 10 minutes period and the reaction was stirred cooled for 40
minutes. The
reaction was quenched with water and concentrated. The crude product was
partitioned
between water and diethyl ether, layers were separated and the organics were
washed with
brine. The organics were concentrated and the resulting solid was triturated
in hexanes,
filtered and dried to give 44.1 g of an off-white solid. The filtrate was
concentrated and there
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were crystals after 3 days. Crystals were filtered and dried to give 1.5 g
pale orange
crystalline solid. Total yield = 78%. 'H NMR (400 MHz, CDC13) 7.86 (dd, 1H),
7.43 (m,
1H), 7.25-7.20 (m, 4H), 7.06 (t, 1H), 4.83 (m, 1H), 3.37 (m, 1H), 2.87 (dd,
1H), 2.57 (s, 3H),
1.42 (s, 9H); MS: M+ = 338.4
[0179] Preparation of (4-Methyl-l l-oxo-10,11-dihydro-dibenzo[b,f]oxepin-10-
yl)-acetic
acid E : The ester D (44.0 g, 128 mmol, 1.0 eq) was dissolved in
dichloromethane (500 mL)
and trifluoroacetic acid (34.5 mL, 448 mmol, 3.5 eq) was added. The reaction
was stirred at
room temperature over 48h. The reaction was diluted with water and the layers
were
separated. The organics were concentrated, triturated in 1:1 diethyl
ether/hexanes (250 mL),
filtered and dried to give 34.6 g of a pale yellow solid (94%). 'H NMR (400
MHz, DMSO)
12.40 (brs, I H), 7.72 (dd, I H), 7.61 (m, I H), 7.44 (m, I H), 7.36-7.30 (m,
3H), 7.18 (t, I H),
4.73 (m, 1H), 3.33 (m, 1H), 2.92 (dd, 1H), 2.57 (s, 3H); MS: (M-H)- = 281.2
[0180] Preparation of N-Methyl-2-(4-methyl-i i-oxo-10,11-dihydro-
dibenzo[b,f]oxepin-10-
yl)-acetamide (F): The acid E (34.5 g, 120 mmol, 1.0 eq) was suspended in
tetrahydrofuran
(200 mL) under nitrogen. To the mixture was added N,N-diisopropylethylamine
(31.3 mL,
180 mmol, 1.5 eq), methyl amine (120 mL, 240 mmol, 2.0 eq) and TBTU (46.2 g,
144 mmol,
1.2 eq). The reaction was stirred at room temperature for 2 hours. Between 30
and 60
minutes, a thick precipitate forms and the reaction turns light green. Another
100 mL of
tetrahydrofuran was added and slow stirring resumed. N,N-dimethylformamide
(100 mL)
was added followed by additional amount of TBTU (15 g). The reaction mixture
was
concentrated to near dryness and the product was partitioned between diethyl
ether and a 50%
aqueous solution of sodium bicarbonate. The aqueous was washed with diethyl
ether and all
organics were combined and concentrated. The resulting solid was triturated in
300 mL 1:1
diethyl ether/hexanes, filtered and dried to give 33.3 g off-white solid
(93%). 1H NMR (400
MHz, CDC13) 7.84 (dd, I H), 7.43 (m, I H), 7.25-7.20 (m, 3H), 7.16 (m, I H),
7.06 (t, I H),
4.96 (dd, 1H), 3.33 (m, 1H), 2.82 (d, 3H), 2.75 (dd, 1H), 2.57 (s, 3H); MS:
(M+H)+ = 296.0
[0181] Preparation of 2-(11-H. day-4-methyl-10,11-dihydro-dibenzo[b,f]oxepin-
10-yl)-N-
methyl-acetamide (G): The ketone F (33.2 g, 112 mmol, 1.0 eq) was partially
dissolved in
methanol / tetrahydrofuran (200 mL/200 mL) under nitrogen and cooled in an
ice/water bath.
Sodium borohydride (10.6 g, 281 mmol, 2.5 eq) was added in 2 g portions over a
15 minutes
period. The ice bath was removed and the mixture was stirred at room
temperature for 1
hour. The reaction was quenched with water and concentrated to near dryness.
The crude
product was suspended in dichloromethane, water was added and the layers were
separated.
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The aqueous layer was washed again with dichloromethane and the organics were
combined
and concentrated. To the resulting foam was added 250 mL of 1:1 diethyl
ether/hexanes with
vigorous stirring. A white precipitate immediately formed and it was filtered
and dried to
give 32 g of a white powder (97%); MS: (M+H)+ = 298.0
[0182] Preparation of 6-Methyl-ll-(2-methylamino-ethyl)-10,11-dih.
dibenzo[b,floxepin-10-ol (H): The amide G (31.9 g, 107mmol, 1.0 eq) was
dissolved in
tetrahydrofuran (200 mL) under nitrogen and the borane-dimethyl sulfide
complex (2.0 M in
tetrahydrofuran, 161 mL, 322 mmol, 3.0 eq) was added dropwise over 15 minutes.
The
reaction was then heated at 80 C for 24 hours. The reaction was cooled in an
ice/water bath
and methanol (50 mL) was added in 10 mL portions over 30 minutes. The mixture
was
stirred for 30 minutes at room temperature. A solution of 4M HC1 in dioxane
(l30 mL, - 5
eq) was added dropwise over 15 minutes. The mixture was stirred at room
temperature for
30 minutes. The mixture was concentrated to near dryness and water and 10%
ethyl
acetate/diethyl ether were added. Layers were separated and the aqueous phase
was washed
with 10% ethyl acetate/diethyl ether. The aqueous layer was basified with a
saturated sodium
bicarbonate solution and the product was extracted with 10%
methanol/dichloromethane.
The organics were combined, dried over sodium sulfate, concentrated and dried
to give 25.8
g of a yellow oil (82%). MS: (M+H)+ = 284.0
[0183] Preparation of [2-(11-h.day-4-methyl-10,11-dihydro-dibenzo[b,floxepin-
10-yl)-
ethyll-methyl-carbamic acid tert-butyl ester (I): To a solution of the amine H
(25.0 g,
86mmol, 1.0 eq, 96.9% pure) and triethylamine (14.3 mL, 102 mmol, 1.2 eq) in
dichloromethane (300 mL) was added di-tert-butyldicarbonate (19.6 g, 90 mmol,
1.05 eq)
portion wise. The reaction was stirred at room temperature for 15 minutes. The
reaction was
diluted with 0.5 M HC1 and the layers were separated. The organics were washed
with 0.5 M
HC1, dried over sodium sulfate, concentrated and dried to give 35 g of a
yellow oil (100%
yield based on 93% purity). MS: (M+H)+ = 384.0
[0184] Preparation of methyll-[2-(4-methyl-dibenzo[b,f]oxepin-10-yl)-ethyll-
carbamic acid
tert-butyl ester (J): The alcohol I (23.5 g, 57 mmol, 1.0 eq, 93% purity) was
dissolved in
dichloromethane (300 mL) and triethylamine (20.6 mL, 148 mmol, 2.6 eq) was
added. The
mixture was cooled in an ice bath and methanesulfonyl chloride (5.73 mL, 74
mmol, 1.3 eq)
was added. The reaction mixture was stirred cooled for 15 minutes. The
reaction mixture
was diluted with 0.5 M HC1 and the layers were separated. The organics were
concentrated
and dried to give 28 g of a crude light yellow oil. The mesylate was dissolved
in toluene (200
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mL) and 1,8-diazabicyclo[5.4.0]undec-7-ene (42.6 mL, 285 mmol, 5.0 eq) was
added. The
mixture was heated at 115 C for 1 hour and diluted with water. The layers were
separated
and the organics were concentrated and purified by a silica gel plug eluting
with 5-15% ethyl
acetate/hexanes to give 14.76 g of a light yellow oil. This total amount was
collected in two
batches (8.44 g, 81% pure by LC/MS) and (6.32 g, 77% pure by LC/MS). 'H NMR
(400
MHz, CDC13) 7.40 (brm, 1H), 7.28 (m, 1H), 7.22-7.10 (m, 3H), 6.98 (m, 2H),
6.70 (brs, 1H),
3.39 (brm, 2H), 2.91-2.82 (brm, 5H), 2.53 (s, 3H), 1.46 (s, 9H); MS: (M+H)+ =
366.0
[0185] Preparation of methyl-[2-(4-methyl-dibenzo[b,loxepin-10-yl)-ethyll-
amine (K):
The olefin J (14.8 g, 32 mmol, 1.0 eq, 79% pure) was dissolved in
dichloromethane (150 mL)
and a solution of HC1 in diethyl ether (2.OM, 75 mL, 160 mmol, 5 eq) was
added. The
mixture was stirred overnight at room temperature. The reaction was diluted
with a solution
of saturated sodium bicarbonate and layers were separated. The aqueous layer
was washed
with 10% methanol/dichloromethane and all organics were combined, concentrated
and
purified by a flash silica gel column using a 2-10% methanol/dichloromethane
gradient (plus
1% NH4OH) to give 8.0 g of a yellow oil in 91% yield and 96% purity. 'H NMR
(400 MHz,
CDC13) 7.38 (m, 1H), 7.30 (m, 2H), 7.15 (m, 2H), 6.99 (m, 2H), 6.74 (s, 1H),
2.93 (t, 2H),
2.78 (t, 2H), 2.52 (s, 3H), 2.44 (s, 3H); MS: (M+H)+ = 266.0
[0186] Preparation of Beloxepin (L): To the amine K (7.0 g, 25 mmol, 1.0 eq)
under
nitrogen was added ethanol (23 mL), an aqueous solution of HC1(2.0 M, 226 mL,
19 eq) and
an aqueous solution of formaldehyde (37%, 100 mL, 52 eq). The reaction mixture
was
heated at 50 C for 64 hours. The reaction mixture was cooled in an ice bath
and it was
basified with 2M NaOH to pH - 8. The product was extracted with 10%
methanol/dichloromethane. The organics were combined, concentrated and
purified by a
flash silica gel column using a 4-9% methanol/dichloromethane gradient (plus
I% NH4OH)
to give 4.9 g white solid in 66% yield and 100% purity. 1H NMR (400 MHz,
CDC13) 7.62
(d, I H), 7.27 (m, 3H), 7.14 (m, I H), 7.08 (m, I H), 7.00 (m, I H), 3.28
(brs, I H), 3.10 (brt,
I H), 3.00 (brm, I H), 2.82 (brm, I H), 2.46 (brs, I H), 2.42 (s, 3H), 2.29
(s, 3H), 2.18 (m, I H),
2.03 (s, 1H), 1.80 (brm, 1H); MS: (M+H)+ = 296Ø CHN Theory (1 mol H2O): %C
72.82
%H 7.40 %N 4.47. CHN Actual (1 mol H2O): %C 72.69 %H 7.29 %N 4.48
[0187] Preparation of M and N: The chiral separation of the racemic mixture L
(racemic
beloxepin) was conducted using the following conditions: (i) Column: Chiralpak
AD-H, 21 x
250mm, 5 micron; (ii) Flow: 15 mL / min, (iii) Mobile phase: 60% Methanol
(0.2%
triethylamine), 20% ethanol, 20% hexane; and (iv) Detection: 270 nm.
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M: Peak Retention Time: Peak 2 [(-)-beloxepin] = 5.8 min. [a]D23.7 = - 111.34
(c.
12.0 mg/mL, MeOH). 1H NMR (400 MHz, CDC13) 7.62 (d, 1H), 7.27 (m, 3H), 7.14
(m,
I H), 7.08 (m, I H), 7.00 (m, I H), 3.27 (brm, I H), 3.08 (t, I H), 2.98 (m, I
H), 2.79 (brm, I H),
2.46 (brs, 1H), 2.41 (s, 3H), 2.27 (s, 3H), 2.15 (m, 1H), 2.07 (brs, 1H), 1.85
(brm, 1H); MS:
(M+H)+ = 296.0; CHN Theory: %C 77.26 %H 7.17 %N 4.74 and CHN Actual: %C 77.16
%H 7.25 %N 4.76
N: Peak Retention Time: Peak 1 [(+)-beloxepin] = 4.7 min. [a]D23.7 = + 110.80
(c.
11.1 mg/mL, MeOH); 1H NMR (400 MHz, CDC13) 7.62 (d, 1H), 7.27 (m, 3H), 7.15
(m,
I H), 7.08 (m, I H), 7.00 (m, I H), 3.27 (brm, I H), 3.08 (t, I H), 2.98 (m, I
H), 2.80 (brm, I H),
2.46 (brs, 1H), 2.42 (s, 3H), 2.28 (s, 3H), 2.15 (m, 1H), 2.05 (s, 1H), 1.80
(brm, 1H); MS:
(M+H)+ = 296.0; CHN Theory: %C 77.26 %H 7.17 %N 4.74 and CHN Actual: %C 76.96
%H7.24 %N4.74.
[0188] Preparation of reconstituted racemic mixture of beloxepin (see Figure
9):
300 mg of (+)-Beloxepin and 300 mg of (-)-Beloxepin were combined and
dissolved in 10
mL of hexanes/methanol (30:70). The solution was concentrated on a rotovap at
37 C to give
an off-white foam (Beloxepin lot 9). 1H NMR (400 MHz, CDC13) consistent for
product.
LC/MS: ESI+ M+ = 295.6; purity = 100% RT = 0.64; CHN Theory: %C 77.26 %H 7.17
%N 4.74, CHN Found: %C 77.04, 77.10 %H 7.17, 7.20 %N 4.77, 4.79
Example 2: Beloxepin Is an Inhibitor of NE Reuptake
[0189] The binding affinities of ( )-, (-)- and (+)-beloxepin for the NE,
dopamine, and
serotonin transporters, as well as the 5HT2A, 5HT2B and 5HT2c receptors were
determined in
competitive binding assays with radiolabeled ligands. The ability of these
compounds to
inhibit reuptake of NE and 5HT, as well as the ability to agonize and
antagonize the 5HT2A,
5HT2B and 5HT2creceptors was also studied. Beloxepin had only marginal
affinity at the
serotonin and dopamine transporters (SERT: 27% inhibition at 10 M, in a
competition
assay; DAT: 16% inhibition at 10 M, in a competition assay).
[0190] The binding affinities of beloxepin for the NE, serotonin and dopamine
transporters
were determined in competitive binding assays with radiolabeled ligands. The
ability of
beloxepin to inhibit reuptake of NE was also determined. It was observed that
beloxepin had
only marginal affinity for the serotonin transporter (27% inhibition of
binding at 10 M in a
competition assay) and dopamine transporter (16% inhibition of binding at 10
M in a
competition assay). Other results observed are provided below.
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[0191] Protocols. For the NE transporter binding assay, [3H]nisoxetine (1.0
nM) was
incubated with various concentrations of beloxepin for 2 hours at 4 C with
membranes
prepared from Chinese hamster ovary cells (CHO) cells heterologously
expressing the cloned
human NE transporter (hNET). Bound radioactivity was determined by
scintillation
spectroscopy. Non-specific binding was defined as the amount of binding that
occurred in
the presence of 1.0 M desipramine. The Ki was determined using standard
methods.
[0192] The IC50 of NE reuptake inhibition was determined by measuring the
degree to which
various concentrations of beloxepin inhibited incorporation of
[3H]norepinephrine into rat
hypothalamus synaptosomes (measurements carried out for 20 minutes at 37 C).
[0193] For the 5HT transporter binding assay, [3H] imipramine (2.0 nM) was
incubated in the
presence of various concentrations of beloxepin for 1 hour at 22 C with
membranes prepared
from CHO cells heterologously expressing the human serotonin transporter
(hSERT). Bound
radioactivity was determined by scintillation spectroscopy. Non-specific
binding was defined
as the amount of binding that occurred in the presence of 10 M imipramine.
The Ki was
determined using standard methods.
[0194] The IC50 of 5HT reuptake inhibition was determined by measuring the
degree to
which various concentrations of beloxepin inhibitied incorporation of [3H]-5HT
into rat brain
synaptosomes (measurements carried out for 15 min at 37 C.
[0195] For the DA transporter binding assay, [3H] N-[1-(2-
benzo[b]thiophenyl)cyclohexyl]-
piperidine ([3H]BTCP) (4.0 nM) was incubated in the presence of various
concentrations of
beloxepin for 2 hr at 4 C with membranes prepared from Chinese hamster ovary
(CHO) cells
heterologously expressing the cloned human dopamine transporter (hDAT). Bound
radioactivity was determined by scintillation spectroscopy. Non-specific
binding was defined
as binding that occurred in the presence of 10 gM BTCP. The K; was determined
using
standard methods
[0196] The IC50 of DA reuptake inhibition was determined by measuring the
degree to which
various concentration of beloxepin inhibited incorporation of [3H]-DA into rat
striatum
synaptosomes (measurements carried out for 15 min at 37 C).
[0197] Results. The K;s and IC50s of beloxepin for the NE, 5HT and DA
transporters are
provided below, showing that beloxepin is a weak, albeit selective, inhibitor
of NE reuptake.
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K,NET = 700 nM
IC50NE = 130 nM
K sERT = 27% inhibition of binding at 10 M in a competition assay
K DAT = 16% inhibition of binding at 10 M in a competition assay
[0198] For the 5HT2A receptor binding assay, [3H]ketanserin (0.5 nM) was
incubated for 60
min at 22 C with membranes prepared from HEK-293 cells heterologously
expressing the
cloned human 5HT2A receptor according to the method of Bonhaus et at., 1995,
Brit. J.
Pharmacol. 115:622-628. Various concentrations of test compound were added and
bound
radioactivity was determined by scintillation counting. Non-specific binding
was determined
in the presence of 1.0 gM unlabeled ketanserin. The K; value for the test
compound was
determined using standard methods.
[0199] For the 5HT2B receptor binding assay, [125I] ( )1,2,5-dimethoxy-4,2-
aminopropane
(DOI) (0.2 nM) was incubated for 15 min at 37 C with membranes prepared from
Chinese
hamster ovary cells heterologously expressing the cloned human 5HT2B receptor
according
to the method of Choi et at., 1994, FEBS Lett 352:393-399. Various
concentrations of test
compound were added and bound radioactivity was determined by scintillation
counting.
Non-specific binding was determined in the presence of 1.0 gM unlabeled DOI.
The K; value
for the test compound was determined using standard methods.
[0200] For the 5HT2c receptor binding assay, [3H]mesulergine (1.0 nM) was
incubated for 60
min at 37 C with membranes prepared from Chinese hamster ovary cells
heterologously
expressing the cloned human 5HT2c receptor according to the method of Stam et
at., 1994,
Eur. J. Pharmacol. 269:339-348. Various concentrations of test compound were
added and
bound radioactivity was determined by scintillation counting. Non-specific
binding was
determined in the presence of 10 gM RS 102221. The K; value for the test
compound was
determined using standard methods.
[0201] Agonist effects at the 5HT2A receptor were assessed by incubation at 22
C of a series
of concentrations of test compound with intact HEK-293 cells heterologously
expressing the
cloned human 5HT2A receptor and measuring intracellular [Ca 2-'-] by
fluorimetry according
to the method of Jerman et at., 2001, Eur. J. Pharmacol. 414:23-30).
Antagonist effects were
assessed by the ability of a series of concentrations of test compound to
block the increase in
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intracellular [Ca 2-1-] that occurred in the presence of 3.0 nM serotonin
under the same
conditions. EC50 and IC50 values were determined using standard methods.
[0202] Agonist effects at the 5HT2B receptor were assessed by incubation at 22
C of a series
of concentrations of test compound with intact CHO cells heterologously
expressing the
cloned human 5HT2B receptor and measuring intracellular [Ca 2-'-] by
fluorimetry according to
the method of Porter et al., 1991, Brit. J. Pharmacol. 128:13-20. Antagonist
effects were
assessed by the ability of a series of concentrations of test compound to
block the increase in
intracellular [Ca 2-1-] that occurred in the presence of 0.3 nM serotonin
under the same
conditions. EC50 and IC50 values were determined using standard methods.
[0203] Agonist effects at the 5HT2c receptor were assessed by incubation at 22
C of a series
of concentrations of test compound with intact CHO cells heterologously
expressing the
cloned human 5HT2c receptor and measuring intracellular [Ca 2-'-] by
fluorimetry according to
the method of Jerman et at., 2001, Eur. J. Pharmacol. 414:23-30. Antagonist
effects were
assessed by the ability of a series of concentrations of test compound to
block the increase in
intracellular [Ca 2-1-] that occurred in the presence of 3.0 nM serotonin
under the same
conditions. EC50 and IC50 values were determined using standard methods.
[0204] Results. The results of the various binding and functional assays are
summarized in
Table 1, reproduced below.
Table 1
Affinity and Activity Data of (+/-), (+), and (-)-beloxepin for Various
Transporters and Receptors
NET 5HT2A 5HT2B 5HT2C
Ka, nM IC50, nM Ka, nM IC50, nM Ka, nM IC50, nM Ka, nM IC50, nM
(f) 700 130 440 5200 1000 >10,000 830 >10,000
antagonist antagonist antagonist
O 390 120 >10,000 nd >10,000 nd >10,000 nd
(+) 2920 1200 97 1600 170 690 84 7200
antagonist antagonist antagonist
nd = not determined
[0205] Racemic ( ) beloxepin is a weak inhibitor of NE reuptake (Ki = 700 nM)
with
marginal affinity at the 5HT and dopamine transporters (SERT: 27% inhibition
at 10 M;
DAT: 16% inhibition at 10 M). Racemic ( ) beloxepin was tested in binding
assays with
over 100 receptors, channels or transporters. From these experiments, it was
determined that
racemic ( ) beloxepin also binds with modest affinity to, and antagonizes, the
5HT2A, 5HT2B
and 5HT2c receptors. These data reveal that racemic ( ) beloxepin is a dual
NRI/5HT2A,2B,2c
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antagonist and that, quite surprisingly, the NRI activity is contributed
virtually exclusively by
the (-) enantiomer and the 5HT2A,2B,2c antagonist activity virtually
exclusively by the
(+) enantiomer.
Example 3: Inhibition of Cytochrome P450 Isoenzyme CYP2D6
by Beloxepin, (-)-Beloxepin, and (+)-Beloxepin
[0206] Protocol. The inhibitory activity of beloxepin , (-)-beloxepin, and (+)-
beloxepin on
cytochrome P450 function was tested using the methods of Chauret (Chauret et
at., 2001,
Drug Metabolism and Disposition, 29(9), 1196-1200) using 7-methoxy-4-
(aminomethyl)-
coumarin (MAMC) (Venhorst et at., 2000, European Journal of Pharmaceutical
Sciences
12(2): 151-158) as substrate. The source of the enzyme was microsomes
containing human
recombinant CYP2D6 obtained from BD Bioscience. Conversion of MAMC to 7-
hydroxy-4-
(aminomethyl)coumarin was measured using a PerkinElmer Fusion with a 390 nm
excitation
filter and a 460 nm emission filter.
[0207] Results. The activity of each of beloxepin , (-)-beloxepin, and (+)-
beloxepin in this
assay is presented in the Table below:
Table 3
CYP2D6 Isoenzyme IC50s (nM)
Compound IC50 (nM)
( )-beloxepin 536
(-)-beloxepin 4370
(+)-beloxepin 236
[0208] Beloxepin was found to inhibit CYP2D6 activity with an IC50 = 536 nM,
(+)-beloxepin was found to inhibit CYP2D6 activity with an IC50 = 236 nM,
while (-
)-beloxepin was found to inhibit CYP2D6 activity with an IC50 = 4370 nM.
[0209] Evaluation of beloxepin as a Direct Inhibitor of Human CYP2D6
(dextromethorphan O-demeth, lam): Microsomal Incubations for ICs0 Estimation
[0210] Protocol: The ability of Beloxepin to inhibit dextromethorphan O-
demethylation
(CYP2D6) was investigated using pooled male human hepatic microsomes.
Beloxepin was
incubated with human liver microsomes at concentrations of 0, 0.1, 0.3, 1, 3,
10, 30 and 100
gM Beloxepin. The 200 gL incubations were conducted in duplicate in 0.1 M
potassium
phosphate buffer (pH 7.4) with 0.02 mg of microsomal protein, 3 MM MgC12, 1 mM
EDTA
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and 7.5 gM of the probe substrate dextromethorphan in a 96-well polypropylene
plate
maintained at 37 C. After a 3-minute pre-incubation, the reaction was
initiated with the
addition of 2 mM NADPH. Upon completion of the 10-minute incubation period,
aliquots of
100 gL were removed and added to a new plate containing 100 gL of internal
standard in
acidified acetonitrile to stop the reaction. The quenched samples were
vortexed and the
precipitated protein was removed by centrifugation. Supernatant aliquots of
100 gL were
transferred to LC vials and 5 gL were injected onto the HPLC system for
LC/MS/MS
analysis of the metabolite dextrorphan. Standards and quality control samples
were similarly
prepared using authentic dextrorphan standards.
[0211] Analytical Method Dexthorphan concentrations were determined by high
performance liquid chromatography with tandem mass spectrometric detection
(LC/MS/MS)
after protein precipitation with acidified acetonitrile containing internal
standard. Separations
were performed with a Flux Rheos 2000 quaternary pump (Leap Technologies,
Inc.,
Carrboro, NC) using an XTerra MS Clg, 3.5 gm, 4.6 x 50 mm column (Waters
Corporation,
Milford, MA). Dextrorphan and the internal standard were eluted with 10 mM
ammonium
formate with 0.1 % formic acid: 0.1 % formic acid in acetonitrile (80:20, v/v)
run under
gradient conditions at 1.0 mL/min. A MDS Sciex API4000 (Applied Biosystems,
Foster
City, CA) triple quadrupole mass spectrometer equipped with a Turbo Ionspray
ionization
source was used as the detector. The instrument was operated in positive ion
mode using
multiple reaction monitoring (MRM) with specific precursor-product ion pairs
for
dextrorphan and the internal standard. The mass transitions were m/z
280.2>262.2 for the
internal standard and m/z 258.2>157.0 for dextrorphan. Dextrorphan and the
internal
standard had retention times of approximately 1.54 and 2.00 minutes,
respectively.
[0212] Results. In this assay (dextromethorphan O-demethylation), Beloxepin
was found to
inhibit CYP2D6 activity with an IC50 = 31.7 gM (FIG. 15).
Example 4: Beloxepin Is Effective In Treating Neuropathic Pain
[0213] Preparation of Vehicle and beloxepin formulations. For this Example and
all that
follow, unless indicated otherwise, beloxepin formulations for injection were
prepared using
acidified sterile water for injection (SWIJ) as a diluent. To start, a few
drops (never more
than 400 gl for a final volume of approximately 14 ml) of 1 M HCl was added to
neat
beloxepin. Glass beads were added and the solution vortexed vigorously for 2-3
minutes,
followed by sonication in a water bath for 3-5 minutes to break up larger
particles. The SWIJ
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was then added to QS to final total volume, the formulation vortexed for 2-3
minutes and
then sonicated in warm water for approximately 30-60 minutes. Beloxepin was
formulated as
a 10 mg/ml solution.
[0214] For this Example and all that follow, unless indicated otherwise,
control vehicle was
prepared using the same volumes of 1 M HC1 and SWIJ diluent as the test
beloxepin
formulation.
[0215] Protocol. The antiallodynic activity of beloxepin was tested in vivo
using the L5-
Single Nerve Ligation ("SNL") model of non-nociceptive neuropathic pain as
described in
LaBuda & Little, 2005, J. Neurosci. Methods 144:175-181. The test animals were
placed in a
Plexiglas chamber (10 cm x 20 cm x 25 cm) and habituated for 15 minutes. The
chamber
was positioned on top of a mesh screen so that von Frey monofilaments could be
presented to
the plantar surface of both hindpaws. Measurement of tactile sensitivity for
each hind paw
were obtained using the up/down method (Dixon, 1980, Annu. Rev. Pharmacol.
Toxicol.
20:441-462) with seven Frey monofilaments (0.4, 1, 2, 4, 6, 8 and 15 grams).
Each trial
started with a von Frey force of 2 grams delivered to the right hind paw for
approximately 1-
2 seconds and then the left hind paw. If there was no withdrawal response, the
next higher
force was delivered. If there was a response, the next lower force was
delivered. This
procedure was performed until no response was made at the highest force (15
grams) or until
four stimuli were administered following the initial response. The 50% paw
withdrawal
threshold for each paw was calculated using the following formula: [Xth]log =
[vFr]log + ky,
where [vFr] is the force of the last von Frey used, k = 0.2249 which is the
average interval (in
log units) between the von Frey monofilaments, and y is a value that depends
upon the
pattern of withdrawal responses (Dixon, 1980, supra). If an animal did not
respond to the
highest von Frey monofilament (15 grams), then the paw was assigned a value of
18.23
grams. Testing for tactile sensitivity was performed twice and the mean 50%
withdrawal
value assigned as the tactile sensitivity for the right and left paws for each
animal. All test
groups contained at least six animals.
[0216] Results. The antiallodynic effects produced by beloxepin (30 mg/kg IP)
in L5 SNL
rats 14 days post surgery are illustrated in FIG. 1. In this experiment, at 14
days post surgery,
rats were treated with vehicle or beloxepin (30 mg/kg IP) and tested for
tactile allodynia at
30, 60, 120 and 240 min post treatment. Vehicle-treated rats were tested at 30
min post
treatment. As illustrated in FIG. 1, beloxepin produced significant
antiallodynia effects at the
30, 60 and 120 min time points, with a maximal effect at 30 min post treatment
(829% of the
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threshold of vehicle-treated rats). The magnitude of tactile allodynia
observed at the 30 min
time point was amongst the highest the inventors have observed in this model.
No side
effects were observed following treatment.
[0217] Results. The antiallodynic effects produced by (-)-beloxepin (30 mg/kg
IP) and
(+)-beloxepin (30 mg/kg IP) in L5 SNL rats 8 days post surgery are illustrated
in FIG. 16. In
this experiment, at 8 days post surgery, rats were treated with vehicle or
beloxepin
enantiomers (30 mg/kg IP) and tested for tactile allodynia at 30 min post
treatment. As
illustrated in FIG. 16, (-)-beloxepin produced significant antiallodynia (444%
of the threshold
of vehicle-treated L5 SNL rats). Although not statistically significant, (+)-
beloxepin
produced an antiallodynic effect that was comparable to that observed with (-)-
beloxepin. No
side effects were observed following treatment with either enantiomer.
[0218] Results: The antiallodynic effects produced by (-)- beloxepin and (+)-
beloxepin (30
mg/kg IP) in L5 SNL rats 14 days post surgery are illustrated in FIG. 17. In
this experiment,
at 14 days post surgery, rats were treated with vehicle, (-)-beloxepin, or (+)-
beloxepin and
tested for tactile allodynia at 30, 60, 120 and 240 min post treatment.
Vehicle treated rats
were tested at 30 min post treatment. As illustrated in FIG. 17, (-)-
beloxepin produced
significant antiallodynic effects at the 30 and 60 min time points, with a
maximal efficacy
corresponding to 635% of the threshold of vehicle-treated rats, while (+)-
beloxepin produced
significant antiallodynic effects at the 30 and 60 min time points, with a
maximal efficacy
corresponding to 423% of the threshold of vehicle-treated rats.
Example 5: Beloxepin Exerts Its Antiallodynic Effect in a Dose-
Dependent Fashion
[0219] Protocol. A dose response experiment was performed in L5 SNL rats at 16
days post
surgery (3, 10 and 30 mg/kg IP beloxepin). In the experiment, animals were
tested for tactile
allodynia at 30 min post treatment. The sham-operated control group, which
were operated
on but not subject to nerve ligation, contained 4 animals. The treatment group
contained at
least six animals.
[0220] The results of the dose-response experiment are illustrated in FIG. 2.
The 30 mg/kg
dose produced a robust antiallodynic effect (852% of the threshold for vehicle-
treated rats,
and almost equal to that of the sham-operated animals). The results observed
replicated the
significant antiallodynic effect observed in the time-course experiments of
Example 4.
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Example 6: Beloxepin is Superior to NE Reuptake Inhibitors, Mixed
Serotonin/NE Reuptake Inhibitors and Tricyclic
Antidepressants in Treatment of Neuropathic Pain
[0221] The results of a direct comparison of beloxepin with reboxetine, are
illustrated in FIG.
3, and demonstrate that beloxepin is approximately 4-fold more effective.
Similarly, FIG. 5
depicts the results of a direct comparison of the antiallodynic effects
produced by beloxepin,
duloxetine, amitriptyline, and reboxetine in the rat L5 Spinal Nerve Ligation
Model (30
mg/kg IP; * p < 0.05 compared to vehicle-treated L5 SNL rats; rats were tested
at 30 minutes
or, for amitriptyline, 60 minutes post-drug administration). The data indicate
that beloxepin
was the most effective of the compounds tested.
Example 7: Beloxepin and (-)-Beloxepin Therapy Is Effective In An
Animal Model of Neuropathic Pain When Administered
Orally
[0222] Protocol. A time course experiment was performed with beloxepin (60
mg/kg PO) in
L5 SNL rats at 8-days post surgery. Rats were tested at 30, 60, 120 and 240
min post
beloxepin. All test groups contained at least six animals.
[0223] Results. The results are provided in FIG. 4. Oral beloxepin produced
significant and
robust antiallodynic effects at the 30 and 60 min time points.
[0224] Protocol. A time course experiment was performed with (-)-beloxepin (60
mg/kg PO)
in L5 SNL rats at 7 days post-surgery. Rats were tested at 30, 60, 120, and
240 minutes post-
drug.
[0225] Results. The (-)-beloxepin enantiomer produced significant
antiallodynic effects at
the 60 and 120 minute time points, as illustrated in FIG. 18.
[0226] Protocol. A time course experiment was also performed with (+)-
beloxepin
(60 mg/kg PO) in L5 SNL rats at 14 days post-surgery. Rats were tested at 30,
60, 120, and
240 minutes post-drug.
[0227] Results. The (+)-beloxepin enantiomer did not produce significant
antiallodynic
effects at any time point (FIG. 19).
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Example 8: Beloxepin and (-)-Beloxepin Are Effective
At Treating Acute Nociceptive Pain
[0228] Protocol. The ability of beloxepin, (-)-beloxepin, and (+)-beloxepin,
to treat acute
nociceptive pain was tested in the rat hot plate model utilizing Male Sprague-
Dawley rats
(150 - 250 g). For the experiment, rats were acclimated to a 50 C hot plate
apparatus by
gently placing them on the hot plate with all four paws on the surface. A
timer was started
and the latency (in seconds) until the rat licked any of its paws was
measured. A 60 second
cut-off to elicit a response was set to prevent tissue damage to the paws.
After the rats
elicited the paw lick response, they were removed from the apparatus and
returned to their
home cages for at least 30 minutes. Baseline paw lick latencies were
determined prior to
drug treatments in an identical manner to the acclimation test. Following drug
treatments, the
rats were placed on the hot plate apparatus at the appropriate time and
treatment paw lick
latencies were determined. All test groups contained at least six animals.
[0229] The paw lick latency was used to determine % MPE for each rat based on
the
following formula:
Treatment Latency (sec) - Baseline Latency (sec)
MPE = x 100
60 sec - Baseline Latency (sec)
Thus, any rats that reach the cut-off have obtained 100% MPE.
[0230] Results. The results of the experiment in which beloxepin was
administered are
illustrated in FIGS. 6A and 6B. FIG. 6A shows the latency (in seconds) between
placement
on the hot plate and paw lick response. 30 and 60 mg/kg beloxepin (IP)
exhibited a
statistically significant robust anti-nociceptive effects, with both dosages
producing anti-
nociceptive activity nearly as effective as 3 mg/kg morphine. FIG. 6B shows
the percentage
of maximal effect achieved (% MPE) in the same experiment.
[0231] Treatment with morphine (3 mg/kg SC) resulted in a level of
antinociception of 61
7% MPE in these experiments. Testing of the (-)- and (+)-enantiomers of
beloxepin in the
rat 50 C hot plate assay demonstrated enantioselective effects, as
illustrated in FIG. 22
((-)-beloxepin) and FIG. 23 ((+)-beloxepin). (-)-Beloxepin displayed robust
antinociceptive
activity at 30, 60, and 120 minutes after treatment, with peak antinociception
of 79 10%
MPE at 30 min post-treatment (FIG. 22). In this experiment, morphine (3 mg/kg
SC)
treatment produced 65 11 % MPE. In contrast, no antinociception was observed
in rats
treated with (+)-beloxepin (FIG. 23), with % MPE that were not significantly
different from
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vehicle-treated rats with % MPE values ranging 10 - 17%. In morphine-treated
rats the level
of antinociception was 85 7% MPE.
Example 9: Beloxepin Is Effective At Treating Inflammatory Pain
[0232] Protocol. The ability of beloxepin to treat inflammatory pain was
tested using
Freund's Complete Adjuvant (FCA)-induced mechanical hyperalgesia in rats. For
the assay,
the methods of DeHaven-Hudkins et at., 1999, J. Pharmacol. Exp. Ther. 289:494-
502 were
used to determine mechanical hyperalgesia in rats 24 hours after intraplantar
administration
of 150 L Freund's Complete Adjuvant (FCA). To determine paw pressure
thresholds, the
rats were lightly restrained in a gauze wrap and pressure was applied to the
dorsal surface of
the inflamed and uninflamed paw with a conical piston using a pressure
analgesia apparatus
(Stoelting Instruments, Wood Dale, IL). The paw pressure threshold was defined
as the
amount of force (in grams) required to elicit an escape response using a
cutoff value of 250
grams. Paw pressure thresholds were determined before and at specified times
after drug
treatment. All test groups contained at least six animals.
[0233] Results. The results are illustrated in FIG. 7. 30 mg/kg beloxepin
nearly completely
reversed hyperalgesia induced by the FCA.
Example 10: Beloxepin Is Effective At Treating Visceral Pain
[0234] Protocol. The ability of beloxepin to treat visceral pain was
demonstrated in a rodent
model of acetic acid-induced writhing For the assay, male ICR mice (20 - 25 g)
were treated
with vehicle or test compound orally 25 min prior to the intraperitoneal
administration of
0.6% of acetic acid. Five minutes after treatment with acetic acid, the number
of writhes was
counted for 10 min. A writhe is defined as the extension of both front and
hind limbs with a
concave stretch of the abdomen. The mean number of writhes was determined for
each
treatment group and the percent inhibition of the vehicle response was
calculated using the
following formula:
Number of writhes after treatment
1 - x100
Number of writhes in vehicle treated mice
[0235] All test groups contained at least six animals.
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[0236] Results. The results are illustrated in FIG. 8. Beloxepin inhibited
acetic acid-induced
writhing in a dose-dependent fashion, with an ED50 of 13.3 mg/kg (oral).
Example 11: A Mixture of (+)-Beloxepin And (-)-Beloxepin Is Effective
In An Animal Model Of Inflammatory Pain (FCA-Induced
Mechanical Hyperalgesia)
[0237] Protocol. A sample of ( )-beloxepin was prepared by milling the
isolated
(+)-beloxepin and (-)-beloxepin enantiomers together, bringing them up in
solvent, and then
removing the solvent ("Lot 9"). In this experiment, 30 mg/kg of ( )-beloxepin
("Lot 7") or
30 mg/kg of the reconstituted racemic mixture (Lot 9) was administered in rats
treated with
FCA for 24 hours. Thirty minutes after treatment with vehicle, ( )-beloxepin,
or
reconstituted racemic mixture, paw pressure thresholds were determined. Thirty
minutes is
the time of peak mechanical antihyperalgesia of ( )-beloxepin.
[0238] Results. As illustrated in FIG. 9, similar mechanical antihyperalgesic
(96 16% vs.
77 11 %) efficacy was observed in rats treated with ( )-beloxepin or the
reconstituted
racemic mixture. Thus, a chemical entity that produces significant mechanical
antihyperalgesia can be provided as the mixture of its two component
enantiomers.
Example 12: Beloxepin Is Effective In An Animal Model Of Neuropathic
Pain (Rat L5 SNL Model)
[0239] Protocol. A time course experiment was performed with beloxepin (60
mg/kg PO in
L5 SNL rats at 7 days post-surgery. Rats were tested at 30, 60, 120, and 240
minutes post-
drug.
[0240] Results. Beloxepin produced significant antiallodynic effects at all
four time points,
as illustrated in FIG. 10.
[0241] Protocol. In a further experiment with this animal model of pain, a
comparison of
the time courses for mechanical antiallodynia in the rat L5 SNL model for
beloxepin,
duloxetine (a drug approved for the treatment of diabetic neuropathy), and
esreboxetine (a
compound in Phase III clinical trials for the treatment of fibromyalgia and
diabetic
neuropathy). The data obtained are depicted in FIG. 11.
[0242] Results. As demonstrated in FIG. 11, racemic beloxepin (30 mg/kg IP)
was
comparable in efficacy to duloxetine (30 mg/kg IP), and the peak antiallodynic
effect of
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racemic beloxepin was greater than that measured in rats treated with
esreboxetine (30 mg/kg
IP).
Example 13: Beloxepin, (-)-Beloxepin, and (+)-Beloxepin Are Effective In
An Animal Model Of Post-Operative Pain
(Rat Hindpaw Incisional Pain Model)
[0243] Protocol. A time course experiment was performed with beloxepin in the
hindpaw
incision model. At 24 hours post surgery, rats received vehicle or beloxepin
(30 mg/kg IP).
Rats were tested for tactile allodynia at 30, 60, 120 and 240 minutes after
administration of
beloxepin.
[0244] Results. As illustrated in FIG. 12, racemic beloxepin produced a
significant
antiallodynic effect at all four time points (maximum hindpaw withdrawal
threshold - 29
grams or 544% of the threshold value for vehicle treated rats at the 30 minute
time point).
The antiallodynic effect produced by racemic beloxepin in this assay is
considered very
robust.
[0245] Protocol. A second time course experiment was performed with racemic
beloxepin
in the hindpaw incision model after oral (PO) administration. At 24 hours post-
surgery, rats
received vehicle or racemic beloxepin (60 mg/kg PO). Rats were tested for
tactile allodynia
at 30, 60, 120 and 240 minutes after administration of beloxepin.
[0246] Results. As illustrated in FIG. 13, racemic beloxepin produced a
significant
antiallodynic effect at all four time points (maximum hindpaw withdrawal
threshold - 24
grams at the 30 and 60 minute time points). The antiallodynic effect produced
by beloxepin
in this assay is considered very robust and is comparable to the effect that
was observed after
IP administration.
[0247] Protocol. A third time course experiment was performed with racemic
beloxepin in
the hindpaw incision model after intravenous (IV) administration. At 24 hours
post-surgery,
rats received vehicle or beloxepin (3 mg/kg IV). The 3 mg/kg IV dose is a dose
that is 10-
fold lower than a dose that produced a significant respiratory or
cardiovascular side effect.
Rats were tested for tactile allodynia at 30, 60, 120 and 240 minutes after
administration of
beloxepin.
[0248] Results. As illustrated in FIG. 14, racemic beloxepin produced a
significant
antiallodynic effect at the 30 and 120 minute time points (maximum hindpaw
withdrawal
threshold - 21 grams at the 30 minute time point). The antiallodynic effect
produced by
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beloxepin in this assay at the 30 minute time point is considered very robust
and comparable
to the antiallodynic effect observed with a dose of 60 mg/kg PO of racemic
beloxepin at the
30 minute time point.
[0249] Protocol. A time course experiment was also performed with (-)-
beloxepin in the
hindpaw incision model. At 24 hours post-surgery, rats received vehicle or (-)-
beloxepin (30
mg/kg IP). Rats were tested for tactile allodynia at 30, 60, 120 and 240
minutes after
administration of (-)-beloxepin.
[0250] Results. As illustrated in FIG. 20, (-)-beloxepin produced a
significant antiallodynic
effect at the 30 and 120 minute time point (maximum hindpaw withdrawal
threshold - 19
grams or 426% of the threshold value for vehicle treated rats at the 30 minute
time point).
The antiallodynic effect produced by (-)-beloxepin at the 30 minute, but not
120 minute, time
point is considered robust.
[0251] Protocol. Another time course experiment was performed with (+)-
beloxepin in the
hindpaw incision model. At 24 hours post-surgery, rats received vehicle or (+)-
beloxepin (30
mg/kg IP). Rats were tested for tactile allodynia at 30, 60, 120 and 240
minutes after
administration of (+) beloxepin.
[0252] Results. As illustrated in FIG. 21, (+)-beloxepin produced a
significant antiallodynic
effect at the 30 and 60 minute time points (maximum hindpaw withdrawal
threshold - 28
grams at the 30 minute time point). The antiallodynic effect produced by (+)-
beloxepin in
this assay is considered very robust and comparable to the effect observed
with racemic
beloxepin at the 30 minute time point.
[0253] While various specific embodiments have been illustrated and described,
it will be
appreciated that various changes can be made without departing from the spirit
and scope of
the invention(s).
[0254] All publications, patents, patent applications and other documents
cited in this
application are hereby incorporated by reference in their entireties for all
purposes to the
same extent as if each individual publication, patent, patent application or
other document
were individually indicated to be incorporated by reference for all purposes.
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