Note: Descriptions are shown in the official language in which they were submitted.
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17715(AP)PCT
ABNORMAL CANNABIDIOLS AS AGENTS FOR LOWERING
INTRAOCULAR PRESSURE AND PROVIDING
NEUROPROTECTIVE EFFECT TO THE EYE
Background of the Invention
1. Field of the Invention
The present invention relates to the use of Abnormal Cannabidiols
to lower the intraocular pressure of mammals and thus are useful in
treating glaucoma. These compounds are also useful as neuroprotective
agents in the eye.
2. Description of the Art
Ocular hypotensive agents are useful in the treatment of a number
of various ocular hypertensive conditions, such as post-surgical and post-
laser trabeculectomy ocular hypertensive episodes, glaucoma, and as
presurgical adjuncts.
Glaucoma is a disease of the eye characterized by increased
intraocular pressure. On the basis of its etiology, glaucoma has been
classified as primary or secondary. For example, primary glaucoma in
adults (congenital glaucoma) may be either open-angle or acute or
chronic angle-closure. Secondary glaucoma results from pre-existing
ocular diseases such as uveitis, intraocular tumor or an enlarged cataract.
The underlying causes of primary glaucoma are not yet known.
The increased intraocular tension is due to the obstruction of aqueous
humor outflow. In chronic open-angle glaucoma, the anterior chamber
and its anatomic structures appear normal, but drainage of the aqueous
humor is impeded. In acute or chronic angle-closure, the anterior
chamber is shallow, the filtration angle is narrowed, and the iris may
obstruct the trabecular meshwork at the entrance of the canal of Schlemm.
Dilation of the pupil may push the root of the iris forward against the
angle, and may produce pupilary block and thus precipitate an acute
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attack. Eyes with narrow anterior chamber angles are predisposed to
acute angle-closure glaucoma attacks of various degrees of severity.
Secondary glaucoma is caused by any interference with the flow of
aqueous humor from the posterior chamber into the anterior chamber and
subsequently, into the canal of Schlemm. Inflammatory disease of the
anterior segment may prevent aqueous escape by causing complete
posterior synechia in iris bombe, and may plug the drainage channel with
exudates. Other common causes are intraocular tumors, enlarged
cataracts, central retinal vein occlusion, trauma to the eye, operative
procedures and intraocular hemorrhage.
Considering all types together, glaucoma occurs in about 2% of all
persons over the age of 40 and may be asymptotic for years before
progressing to rapid loss of vision. In cases where surgery is not
indicated, topical a-adrenoreceptor antagonists have traditionally been
the drugs of choice for treating glaucoma.
It has long been know that one of the sequelae of glaucoma is
damage to the optic nerve head. This damage, referred to as "cupping",
results in depressions in areas of the nerve fiber of the optic disk. Loss of
sight from this cupping is progressive and can lead to blindness if the
condition is not treated effectively.
Unfortunately lowering intraocular pressure by administration of
drugs or by surgery to facilitate outflow of the aqueous humor is not
always effective in obviating damage to the nerves in glaucomatous
conditions. This apparent contradiction is addressed by Cioffi and Van
Buskirk [Surv. of Ophthalmol., 38, Suppl. p. S107-16, discussion S116-17,
May 1994] in the article, "Microvasculature of the Anterior Optic
Nerve". The abstract states:
The traditional definition of glaucoma as a disorder of
increased intraocular pressure (IOP) oversimplifies the clinical
situation. Some glaucoma patients never have higher than
normal IOP and others continue to develop optic nerve
damage despite maximal lowering of IOP. Another possible
factor in the etiology of glaucoma may be regulation of the
regional microvasculature of the anterior optic nerve. One
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reason to believe that microvascular factors are important is
that many microvascular diseases are associated with
glaucomatous optic neuropathy.
Subsequent to Cioffi, et al., Matusi published ' a paper on the
"Ophthalmologic aspects of Systemic Vasculitis" [Ni on Rinsho, 52 (8),
p. 2158-63, August 19941 and added further support to the assertion that
many microvascular diseases are associated with glaucomatous optic
neuropathy. The summary states:
Ocular findings of systemic vasculitis, such as polyarteritis
nodosa, giant cell angitis and aortitis syndrome were reviewed.
Systemic lupus erythematosus is not categorized as systemic
vasculitis, however its ocular findings are rnicroangiopathic.
Therefore, review of its ocular findings was included in this
paper. The most common fundus finding in these diseases is
ischemic optic neuropathy or retinal vascular occlusions.
Therefore several points in diagnosis or pathogenesis of optic
neuropathy and retinal and choroidal vaso-occlusion were
discussed. Choroidal ischemia has come to be able to be
diagnosed clinically, since fluorescein angiography was
applied in these lesions. When choroidal arteries are occluded,
overlying retinal pigment epithelium is damaged. This causes
disruption of barrier function of the epithelium and allows
fluid from choroidal vasculatures to pass into subsensory
retinal spaces. This is a pathogenesis of serous detachment of
the retina. The retinal arterial occlusion formed non-perfused
retina. Such hypoxic retina released angiogenesis factors which
stimulate retinal and iris neovascularizations and iris
neovascularizations may cause neovascular glaucoma.
B. Schwartz, in "Circulatory Defects of the Optic Disk and Retina
in Ocular Hypertension and High Pressure Open-Angle Glaucoma"
[Surv. Ophthalmol., 38, Suppl. pp. S23-24, May 19941 discusses the
measurement of progressive defects in the optic nerve and retina
associated with the progression of glaucoma. He states:
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Fluorescein defects are significantly correlated with visual field
loss and retinal nerve fiber layer loss. The second circulatory
defect is a decrease of flow of fluorescein in the retinal vessels,
especially the retinal veins, so that the greater the age, diastolic
blood pressure, ocular pressure and visual field loss , the less
the flow. Both the optic disk and retinal circulation defects
occur in untreated ocular hypertensive eyes. These
observations indicate that circulatory defects in the optic disk
and retina occur in ocular hypertension and open-angle
glaucoma and increase with the progression of the disease.
Certain Abnormal Cannabidiols are disclosed in Howlett et al,
"International Union of Pharmacology. XXVII. Classification of
Cannabinoid Receptors", Pharmacological Reviews 54:161-202, 2002.
Summary of the Invention ~
We have found that Abnormal Cannabidiols are potent ocular
hypotensive agents. We have further found that Abnormal Cannabidiols
and homologues and derivatives thereof, are especially useful in the
treatment of glaucoma and surprisingly, cause no or significantly lower
ocular surface hyperemia than the other compounds that are useful in
lowering intraocular pressure, e.g. PGFza and lower alkyl esters thereof.
We have also found that Abnormal Cannabidiols are potent
neuroprotective agents. We have further found that Abnormal
Cannabidiols and homologues and derivatives thereof are especially
useful in providing a neuroprotective effect to the eye of a mammal, e.g. a
human.
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The present invention relates to methods of treating ocular
hypertension in and providing neuroprotection to the eye, e.g. the eye of
a mammal, such as a human, which comprises administering an effective
amount of a compound represented by the formula I
R
HO &IOH
wherein R is selected from the group consisting of (CH2),, wherein x is 0
or an integer of from 1 to 7.
In a further aspect, the present invention relates to pharmaceutical
compositions comprising a therapeutically effective amount of a
compound of formulae (I), in admixture with an non-toxic,
pharmaceutically acceptable liquid vehicle.
Brief Description of the Drawing Figures
Figure 1 shows the effect of 0.1% Abnormal Cannabidiol on Dog
Intraocular Pressure versus time.
Figure 2 shows the effect of 0.1% Abnormal Cannabidiol on
Monkey Intraocular Pressure versus time.
Figure 3 shows the change from baseline IOP of Monkey dosed
with 0.1% Abnormal Cannabidiol versus time.
Detailed Description of the Invention
The present invention relates to the use of Abnormal Cannabidiols
as ocular hypotensives. These therapeutic agents are represented by
compounds having the formula I:
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R
HO OH
as defined above. The preferred compounds used in accordance with the
present invention are encompassed by the following structural formula
II
O OH
or III
0 OH
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In all of the above formulae, as well as in those provided
hereinafter, the straight lines represent bonds. Where there is no symbol
for the atoms between the bonds, the appropriate carbon-containing
radical is to be inferred. For example in formula II, the radical extending
from the phenyl ring is a polymethylene (CH2) radical terminated with a
methyl radical, i.e. a butylenylmethyl radical.
Pharmaceutical compositions may be prepared by combining a
therapeutically effective amount of at least one compound according to
the present invention, as an active ingredient, with conventional
ophthalmically acceptable pharmaceutical excipients, and by preparation
of unit dosage forms suitable for topical ocular use. The therapeutically
efficient amount typically is between about 0.0001 and about 5% (w/v),
preferably about 0.001 to about 1.0% (w/v) in liquid formulations.
For ophthalmic application, preferably solutions are prepared
using a physiological saline solution as a major vehicle. The pH of such
ophthalmic solutions should preferably be maintained between 4.5 and
8.0 with an appropriate buffer system, a neutral pH being preferred but
not essential. The formulations may also contain conventional,
pharmaceutically acceptable preservatives, stabilizers and surfactants.
Preferred preservatives that may be used in the pharmaceutical
compositions of the present invention include, but are not limited to,
benzalkonium chloride, chlorobutanol, thimerosal, phenylmercuric
acetate and phenylmercuric nitrate. A preferred surfactant is, for example,
Tween 80. Likewise, various preferred vehicles may be used in the
ophthalmic preparations of the present invention. These vehicles include,
but are not limited to, polyvinyl alcohol, povidone, hydroxypropyl
methyl cellulose, poloxamers, carboxymethyl cellulose, hydroxyethyl
cellulose and purified water.
. Tonicity adjustors may be added as needed or convenient. They
include, but are not limited to, salts, particularly sodium chloride,
potassium chloride, mannitol and glycerin, or any other suitable
ophthalmically acceptable tonicity adjustor.
Various buffers and means for adjusting pH may be used so long
as the resulting preparation is ophthalmically acceptable. Accordingly,
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buffers include acetate buffers, citrate buffers, phosphate buffers and
borate buffers. Acids or bases may be used to adjust the pH of these
formulations as needed.
In a similar vein, an ophthalmically acceptable antioxidant for use
in the present invention includes, but is not limited to, sodium
metabisulfite, sodium thiosulfate, acetylcysteine, butylated
hydroxyanisole and butylated hydroxytoluene.
Other excipient components which may be included in the
ophthalmic preparations are chelating agents. The preferred chelating
agent is edentate disodium, although other chelating agents may also be
used in place or in conjunction with it.
The ingredients are usually used in the following amounts:
Table 1
Ingredient Amount (% w/v)
active ingredient about 0.001-5
preservative 0-0.10
vehicle 0-40
tonicity adjustor 1-10
buffer 0.01-10
pH adjustor q.s. pH 4.5-7.5
antioxidant as needed
surfactant as needed
purified water as needed to make 100%
The actual dose of the active compounds of the present invention
depends on the specific compound, and on the condition to be treated; the
selection of the appropriate dose is well within the knowledge of the
skilled artisan.
The ophthalmic formulations of the present invention are
conveniently packaged in forms suitable for metered application, such as
in containers equipped with a dropper, to facilitate application to the eye.
Containers suitable for dropwise application are usually made of suitable
inert, non-toxic plastic material, and generally contain between about 0.5
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and about 15 mi solution. One package may contain one or more unit
doses.
Especially preservative-free solutions are often formulated in non-
resealable containers containing up to about ten, preferably up to about
five unit doses, where a typical unit dose is from one to about 8 drops,
preferably one to about 3 drops. The volume of one drop usually is about
20-35 l.
The compounds disclosed herein for use in the method of this
invention, i.e. the treatment of glaucoma or elevated intraocular
pressure, may also be used in combination with other drugs useful for
the treatment of glaucoma or elevated intraocular pressure.
Fo-r the treatment of glaucoma or elevated intraocular pressure,
combination treatment with the following classes of drugs are
contemplated:
O-Blockers (or 0-adrener 'glc antagonists) including carteolol, levobunolol,
metipranolol, timolol hemihydrate, timolol maleate, (31-selective
antagonists such as betaxolol, and the like, or pharmaceutically
acceptable salts or prodrugs thereof;
Adrenergic Agonists including
non-selective adrenergic a og nistssuch as epinephrine borate,
epinephrine hydrochloride, and dipivefrin, and the like, or
pharmaceutically acceptable salts or prodrugs thereof; and
2 selective adrenergic a og nists such as apraclonidine, brimonidine, and
the like, or pharmaceutically acceptable salts or prodrugs thereof;
Carbonic Anhydrase Inhibitors including acetazolamide,
dichlorphenamide, methazolamide, brinzolamide, dorzolamide, and the
like, or pharmaceutically acceptable salts or prodrugs thereof;
Cholinergic A og nists including
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direct acting cholinergic agonists such as carbachol, pilocarpine
hydrochloride, pilocarpine nitrate, pilocarpine, and the like, or
pharmaceutically acceptable salts or prodrugs thereof;
chlolinesterase inhibitors such as demecarium, echothiophate,
physostigmine, and the like, or pharmaceutically acceptable salts or
prodrugs thereof;
Glutamate Antagonists such as memantine, amantadine, rimantadine,
nitroglycerin, dextrophan, detromethorphan, CGS-19755,
dihydropyridines, verapamil, emopamil, benzothiazepines, bepridil,
diphenylbutylpiperidines, diphenylpiperazines, HOE 166 and related
drugs, fluspirilene, eliprodil, ifenprodil, CP-101,606, tibalosine, 2309BT,
and 840S, flunarizine, nicardipine, nifedimpine, nimodipine,
barnidipine, lidoflazine, prenylamine lactate, amiloride, and the like, or
pharmaceutically acceptable salts or prodrugs thereof;
Prostamides such as bimatoprost, or pharmaceutically acceptable salts
or prodrugs thereof; and
Prostaglandins including travoprost, UFO-21, chloprostenol,
fluprosteno1,13,14-dihydro-chloprostenol, isopropyl unoprostone,
latanoprost and the like.
The invention is further illustrated by the following non-limiting
Examples.
Example 1
Abnormal Cannabidiol, also named as Abn-CBD (4-[(1R,6R)-3-
Methyl-6-(1-methylethenyl)-2-cyclohexen-1-yl]-5-pentyl-1,3-benzenediol,
M.W. 314.47, may be purchased from Tocris Cookson Inc., Ellisville, MO,
USA.
The above compound is well known and may be purchased or
synthesized by methods known in the art.
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Example 2
Intraocular Pressure
Intraocular pressure was measured by applanation
pneumatonometry in conscious animals. The test compound was
administered topically to one eye while vehicle was given to the fellow
eye in a masked fashion. Ocular normotensive Beagle dogs (males,
females) were dosed once daily for five days. Laser-induced unilaterally
ocular hypertensive Cynomolgus monkeys (females) were dosed once
daily for 4 days. Student's paired t-test was used for statistical
comparisons. Differences were considered statistically significant if the P-
value is less than 0.05.
The results are shown in Figures 1, 2 and 3.
In particular, Figure 1 shows the effect of 0.1% Abnormal
Cannabidiol on Dog Intraocular Pressure versus time.
Figure 2 shows the effect of 0.1% Abnormal Cannabidiol on
Monkey Intraocular Pressure versus time.
Figure 3 shows the change from baseline IOP of Monkey dosed
with 0.1% Abnormal Cannabidiol versus time.
Example 3
Determination of Abnormal Cannabidiol Activity
Abnormal Cannabidiol receptor activity may be measured in
accordance with the procedure disclosed in (Wagner JA et al.,
Hypertension 33 [part II], 429 (1999); Jarai Z et al., PNAS 96, 14136 (1999),
which is hereby incorporated by reference in its entirety.
Example 4
Method of Measuring a Neurol-2rotective Effect
The dissection and dissociation of the rat hippocampal neuron cell
cultures is carried out. Briefly, whole cerebral neocortices are removed
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from fetal rats, gestation age 15-19 days and kept in calcium free and
magnesium free Hanks' balanced salt solution. The hippocampi are
removed under a dissecting microscope and the meninges are stripped
away. When all the hippocampi are removed, the tissues are incubated in
0.05% trypsin solution for 30 minutes at 37 C. At the end of 340 minutes,
the trypsin solution is replaced with plating medium (minimal essential
medium supplemented with 2% Hyclone horse serum, 1% fetal calf
serum, 25 mM glucose, 1% glutamine and 1% penicillin/streptomycin
and N2 supplement). Then the tissues are triturated with a Pasteur
pipette 10 times and then again with a pipette whose tip has been fire
polished to about half the normal diameter. The dissociated neuronal
cells then are plated on poly D-lysine coated, 15 mm 24 well plates (2x105
cells/well) in plating medium.
The cell cultures are kept at 37 C in a humidified, 5% COa
containing atmosphere. After 1-2 days, the horse serum level in the
plating media is increased to 8%. After 4-7 days, the non-neuronal cell
division is halted by 24 hours exposure to 10-6M Cytosine arabinoside
(ARA-C), and the cells are then placed into growing medium with 4%
horse serum,1 l fetal calf serum, 25 mM
glucose, 1% glutamine and 1% penicillin/streptomycin and N2
supplement. Subsequent medium replacement is carried out every other
day until the neuronal cells mature (15-20 days). Only matured cell
cultures are selected for study.
Exposure of the excitatory amino acids is performed in minimal
essential medium (MEM). Extreme care is taken to wash out the growing
medium from cultures before the addition of the excitatory amino acid
since the neurons are very sensitive to disturbance. Matured cell cultures
are exposed to either glutamate, a-amino-3-hydroxy-5-methyl-4-isoxazole
propionic acid (AMPA), N-methyl-D-aspartate (NMDA), or kainic acid.
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Cytotoxicity or cell injury is scored by light microscopy
examination with trypan blue. In most experiments, the overall neuronal
cell injury is quantitated by the amount of lactate dehydrogenase (LDH)
released by the damaged cells into the media 24 hours after drug
exposure.
LDH is measured at room temperature using Promega non-
radioactive cytotoxicity assay kit. The absorbance of the reaction
mixture is measured at 490 nm.
The effect of the Abnormal Cannabidiol of Example 1 on NMDA-
induced neurotoxicity shows that the compound of Example 1 has a
neuroprotective effect.
Example 5
Method of Measuring a Neuroprotective Effect
The Experiment of Example 4 is repeated with other Abnormal
Cannabidiols and the results are essentially as shown for the compound
of Example 1.
Example 6
Measuring Uveoscleral Outflow of Mammals Treated with Abnormal
Cannabidiols
Effect of abnormal cannabidio10.1%, topical once-daily for 5 days, vs
vehicle on Outflow Facility (ul/min/mm Hg), mean sem is shown in
Table 2, below.
Table 2
Baseline Treatment
(no treatment) (abnormal cannabidiol vs
vehicle)
Treated Eye 0.54 0.10 0.57 0.08
Control Eye 0.51 0.14 0.65 0.10
Ratio, 1.19 0.17 0.93 0.09
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Treated:Control
Student's t-test, paired analysis, showed no significant differences
between means.
n = 6 animals
Effect of abnormal cannabidiol 0.1%, topical once-daily for 5 days, vs
vehicle on Uveosclearal Outflow (ul/min), mean sem
Treated Eye 0.58 0.17
Control Eye 0.75 0.23
Ratio, Treated:Control 0.78 0.05
Student's t-test, paired analysis, showed no significant differences
between means.
n = 5 animals
These experimental findings indicate that abnormal cannabidiol
0.1%, given topically once-daily for 5 days to eyes of ocular
normotensive nonhuman primates (cynomolgus monkeys), had no
significant effects on total outflow facility and uveoscleral outflow
compared to baseline and/or contralateral vehicle-treated control eyes.
This indicates that the mechanism of the IOP lowering effects of
abnormal cannabidiol may likely involve no or minor increases in
aqueous outflow. Consequently, the intraocular pressure lowering
effects of abnormal cannabidiol is anticipated to predominantly involve
reduction of aqueous humor formation in humans and nonhuman
primates.
Thus, a combination product containing an Abnormal
Cannabidiols component and an ocular hypotensive agents component
that enhances aqueous humor outflow via either or both the trabecular
and uveoscleral outflow pathways is contemplated for effective
reduction of intraocular pressure based on different modes of action and
complementary pharmacology of the active ingredients.
The combination treatment with the following classes of drugs is
contemplated: Cholinergic agonists including direct acting cholinergic
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agonists such as carbachol, pilocarpine hydrochloride, pilocarpine
nitrate, pilocarpine, and the like, or pharmaceutically acceptable salts or
prodrugs thereof; cholinesterase inhibitors such as demecarium,
echothiophate, physostigmine, and the like, or pharmaceutically
acceptable salts or prodrugs thereof; prostamides such as bimatoprost,
or pharmaceutically acceptable salts or prodrugs thereof; prostaglandins
including travoprost, UFO-21, cloprostenol, fluprostenol, 13,14-dihydro-
cloprostenol, isopropyl unoprostone, latanoprost, prostaglandin EP
analogs such as butaprost, AH-13205 and the like.
The foregoing description details specific methods and
compositions that can be employed to practice the present invention,
and represents the best mode contemplated. However, it is apparent
from one of ordinary skill in the art that different pharmaceutical
compositions may be prepared and used with substantially the same
results. That is, other Abnormal Cannabidiols, will effectively lower
intraocular pressure and provide neuroprotection in animals and are
within the broad scope of the present invention.
