Note: Descriptions are shown in the official language in which they were submitted.
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COMPOSITIONS THAT PREFERENTIALLY POTENTIATE SUBTYPES
OF GABAA RECEPTORSAND METHODS OF USE THEREOF
Cross-Reference to Related Applications
This application claims the benefit of, and priority to, U.S. Provisional
Patent Application
No. 62/907,763, filed September 30, 2019, the contents of which are
incorporated by reference.
Field of the Invention
The invention relates generally to compositions containing neurosteroids and
methods of
using the same to treat GABAA disorders in a subject.
Background
According the World Health Organization (WHO), neurological disorders affect
up to
one billion people worldwide. Neurological disorders include a wide range of
conditions, such
as Alzheimer's disease, brain injuries, epilepsy, headache, infections,
multiple sclerosis, and
Parkinson's disease, and stroke. Many neurological disorders stem from altered
signaling by
receptors for the neurotransmitter y-aminobutyric acid (GABA). GABAA receptors
are
pentameric transmembrane receptors that include various combinations of 19
different subunit
polypeptides. At least 15 GABAA receptor subtypes are known, and particular
subtypes are
associated with different conditions. For example, altered activity of
receptor subtypes that
include az or a3 subunits is associated with anxiety disorders, whereas as-
containing subtypes
appear to play a role in memory and cognition.
Neuroactive steroids that alter the activity of GABAA receptors have been
investigated as
drug candidates for a variety of neurological disorders. However, the
therapeutic potential of
such molecules remains largely untapped. One reason for the shortfall is that
the large number
of chemical variants that can be made from the steroid structural core makes
it difficult to know
whether compounds currently being investigated have superior pharmacological
properties to
other molecules that have not yet been made or analyzed. Another issue is that
the structural
similarity of different GABAA receptor subtypes makes it challenging to
identify molecules with
a desired subtype specificity. Consequently, millions of people continue to
suffer from
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neurological conditions due to the limited arsenal of neuroactive steroids
currently at our
disposal.
Summary
The invention provides compositions that contain isomerically pure forms of
selected
neurosteroids. The invention recognizes that interactions between
neurosteroids and GABAA
receptors are highly sensitive to the stereochemical structure of the
neurosteroids and that certain
neurosteroids display strong GABAA receptor subtype specificity when provided
in compositions
that are substantially free of isomeric contaminants. Because the compositions
of the invention
selectively target particular GABAA receptor subtypes, they have greatly
improved
pharmacological efficacy over prior compositions, including those that contain
biologically
active compounds contaminated with isomers that are less active.
In a particular embodiment, the invention provides compositions that contain
an
isomerically pure form of a compound of Formula (I):
,r,...N
..--,
N. h
N''''
0,, .... j
r,-=,1.....
1,
f 1 H 1
--"' .---4,--.':-----,
A i A
H0, = ' ,,, .....--".. ,,,,,,--j
11 (I).
The present invention includes the finding that isomerically pure compositions
of Formula (I) are
considerably more active on a4f336 GABAA receptors than on a1f32y2 GABAA
receptors. As
described herein, such compositions modulate the activity of a4f336 receptors
with an ECso at
least 5-fold lower than for a1f32y2 receptors. Without wishing to be bound by
a particular
theory, it is believed that the stereochemical configurations at all of the
chiral centers of the
molecule and the atomic bonding patterns within the molecule are important in
conferring
GABAA receptor subtype selectivity. Thus, mixtures that contain the compound
of Formula (I)
together with isomers thereof, such as regioisomers of Formula (I) or
stereoisomers that differ
structurally from Formula (I) at only a single chiral center, lack such
selectivity. Because
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compositions that contain an isomerically pure form of the compound of Formula
(I)
preferentially target a4f336 GABAA receptors, they are useful for therapeutic
applications in
which altering the activity of this receptor is beneficial.
In an aspect, the invention provides pharmaceutical compositions containing an
isomerically pure form of a compound of Formula (I):
N, Q
0..,.. j
t-
f : H i
A i A
11 (I),
wherein the compound of Formula (I) is present in a therapeutically effective
amount to
preferentially potentiate an a4f336 GABAA receptor as compared to an a1f32y2
GABAA receptor.
In another aspect, the invention provides methods for treating a GABAA
disorder by
providing to a subject a pharmaceutical composition comprising an isomerically
pure form of a
compound of Formula (I):
.......N
)7.
An-st?
N'
4-\
r
I I: ,.., : :,
t:i 1 1:1
Pi (I),
wherein the compound of Formula (I) is present in a therapeutically effective
amount to
preferentially potentiate an a4f336 GABAA receptor as compared to an a1f32y2
GABAA receptor.
The composition may be chemically pure, i.e., free from other molecules or
chemical
species. For example, the other molecule or chemical species may have a
distinct chemical
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formula, structural formula, empirical formula, molecular formula, or
condensed formula. The
composition may have a defined level of chemical purity. For example, the
compound of
Formula (I) may be present at at least 95% by weight, at least 96% by weight,
at least 97% by
weight, at least 98% by weight, at least 99% by weight, at least 99.5% by
weight, at least 99.6%
by weight, at least 99.7% by weight, at least 99.8% by weight, or at least
99.9% by weight of the
total amount of a mixture that includes the compound of Formula (I) and one or
more distinct
molecules or chemical species.
The composition may be isomerically pure with respect to all isomers. The
composition
may be isomerically pure with respect to one or more particular types of
isomers. The
composition may be substantially free of structural isomers or a particular
type of structural
isomers, such as a regioisomers. The composition may be substantially free of
stereoisomers or
a particular type of stereoisomers, such as enantiomers or diastereomers.
The composition may contain the compound of Formula (I) at any level of
isomeric
purity to achieve preferential modulation of an a4f336 GABAA receptor as
compared to an
a1f32y2 GABAA receptor. For example, the compound of Formula (I) may be
present at at least
95% by weight, at least 96% by weight, at least 97% by weight, at least 98% by
weight, at least
99% by weight, at least 99.5% by weight, at least 99.6% by weight, at least
99.7% by weight, at
least 99.8% by weight, or at least 99.9% by weight of the total amount of
isomeric molecules that
include the compound of Formula (I) and an isomer thereof.
The composition may contain the compound of Formula (I) and be substantially
free of
stereoisomers. The stereoisomer may differ from Formula (I) at one, two,
three, four, five, six,
seven, or eight chiral centers. The stereoisomer may be a diastereomer or an
enantiomer. For
example, the stereoisomer may be a compound of Formulas (II) or (III):
0
zõ
A
HO1 =
(II), and
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0
\,.
. \ s
, s \
Ei.,.,,,...ii N :)---CNI
=, -/
tfi, 1 H i H
I
H
(III).
The composition may contain one or more stereoisomers of the compound of
Formula (I), such
as a compound of Formula (II) or (III), at less than 5%, less than 4%, less
than 3%, less than 2%,
less than 1%, less than 0.5%, or less than 0.1% of the total of the compound
of Formula (I) and
the one or more stereoisomers thereof. The composition may contain the
compound of Formula
(I) and one or more stereoisomer thereof at a ratio of at least 19:1,
20:1,25:1, 30:1,40:1, 50:1,
100:1, 200:1, 500:1, or 1000:1.
The compound may potentiate a GABAA receptor, a GABAA receptor subtypes, or a
subset of GABAA receptor subtypes by any mechanism. The compound may
potentiate a
GABAA receptor, subtype, or subset by allosteric modulation, activation, or
inhibition. The
allosteric modulation may be positive or negative.
The composition may preferentially potentiate an a4036 GABAA receptor as
compared to
an a1f32y2 GABAA receptor to any degree. The composition may preferentially
potentiate an
a4036 GABAA receptor as compared to an a1f32y2 GABAA receptor by any measure
or
parameter.
The composition may have an ECso for a4036 GABAA receptors that is lower than
the
ECso for a1f32y2 GABAA receptors. The ECso for a4036 GABAA receptors may be
lower than
the ECso for a1f32y2 GABAA receptors by about 2-fold, about 3-fold, about 4-
fold, about 5-fold,
about 6-fold, about 7-fold, about 8-fold, about 10-fold, about 20-fold, about
50-fold, about 100-
fold, about 200-fold, about 500-fold, or about 1000-fold. The ECso for a4036
GABAA receptors
may be less than about 50%, less than about 40%, less than about 30%, less
than about 25%, less
than about 20%, less than about 15%, less than about 10%, less than about 5%,
less than about
4%, less than about 3%, less than about 2%, less than about 1%, less than
about 0.5%, less than
about 0.2%, or less than about 0.1% of the EC50 for al f32y2 GABAA receptors.
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The composition may have a binding affinity (which may be expressed, e.g., as
a
dissociation constant KD) for a4f336 GABAA receptors that is lower than the
binding affinity for
a1f32y2 GABAA receptors. The binding affinity for a4f336 GABAA receptors may
be lower than
the binding affinity for a1f32y2 GABAA receptors by about 2-fold, about 3-
fold, about 4-fold,
about 5-fold, about 6-fold, about 7-fold, about 8-fold, about 10-fold, about
20-fold, about 50-
fold, about 100-fold, about 200-fold, about 500-fold, or about 1000-fold. The
binding affinity
for a4f336 GABAA receptors may be less than about 50%, less than about 40%,
less than about
30%, less than about 25%, less than about 20%, less than about 15%, less than
about 10%, less
than about 5%, less than about 4%, less than about 3%, less than about 2%,
less than about 1%,
less than about 0.5%, less than about 0.2%, or less than about 0.1% of the
binding affinity for
a1f32y2 GAB AA receptors.
The composition may have an ECso for a4f336 GABAA receptors that is below a
defined
value. The composition may have an ECso for a4f336 GABAA receptors that is
less than about 1
less than about 500 nM, less than about 400 nM, less than about 300 nM, less
than about
200 nM, less than about 100 nM, less than about 50 nM, less than about 25 nM,
less than about
10 nM, less than about 5 nM, less than about 2.5 nM, less than about 1 nM,
less than about 0.5
nM, less than about 0.25 nM, or less than about 0.1 nM.
The composition may have a binding affinity for a4f336 GABAA receptors that is
below a
defined value. The composition may have an binding affinity for a4f336 GABAA
receptors that
is less than about 1 tM, less than about 500 nM, less than about 400 nM, less
than about 300
nM, less than about 200 nM, less than about 100 nM, less than about 50 nM,
less than about 25
nM, less than about 10 nM, less than about 5 nM, less than about 2.5 nM, less
than about 1 nM,
less than about 0.5 nM, less than about 0.25 nM, or less than about 0.1 nM.
The composition may be effective for treatment of a GABAA disorder. The GABAA
disorder may be any disease, disorder, or condition associated with altered
GABAA receptor
function or any disorder may be disease, disorder, or condition that can be
ameliorated by altered
GABAA receptor function. The GABAA disorder may be acute pain, an addictive
disorder,
Alzheimer's disease, Angelman's syndrome, anti-social personality disorder, an
anxiety disorder,
attention deficit hyperactivity disorder (ADHD), an attention disorder, an
auditory disorder,
autism, an autism spectrum disorder, bipolar disorder, chronic pain, a
cognitive disorder, a
compulsive disorder, a convulsive disorder, dementia, depression, dysthymia,
an epileptic
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disorder, essential tremor, epileptogenesis, fragile X syndrome, generalized
anxiety disorder
(GAD), Huntington's disease, injury related pain syndrome, insomnia, ischemia,
Lewis body
type dementia, a memory disorder, migraines, a mood disorder, movement
disorder, a
neurodegenerative disease, neuropathic pain, an obsessive compulsive disorder,
pain, a panic
disorder, Parkinson's disease, a personality disorder, posttraumatic stress
disorder (PTSD),
psychosis, Rett syndrome, a schizoaffective disorder, schizophrenia, a
schizophrenia spectrum
disorder, a seizure disorder, a sleep disorder, social anxiety disorder,
status epilepticus, stress,
stroke, tinnitus, traumatic brain injury (TBI), vascular disease, vascular
malformation, vascular
type dementia movement disorder, Wilson's disease, or withdrawal syndrome.
The composition may be formulated for administration by a particular
mechanism. The
composition may be formulated for oral, intravenous, enteral, parenteral,
dermal, buccal, topical
nasal, or pulmonary administration. The composition may be formulated for
administration by
injection or on an implantable medical device (e.g., stent or drug-eluting
stent or balloon
equivalents).
The composition may be formulated a single daily dosage. The composition may
be
formulated for multiple daily dosages, e.g., two, three, four, five, six or
more daily dosages.
The composition may be provided to the subject according to any dosing
schedule. The
composition may be provided once per day. The composition may be provided
multiple times
per day. The composition may be provided two time, three times, four times,
five times, six
times, or more per day.
Detailed Description
The invention provides compositions that contain isomerically pure forms of
neurosteroids and methods of using such compositions to treat neurological and
other disorders.
The invention is based on the recognition that isomerically pure neurosteroids
allow modulation
of specific subtypes of y-aminobutyric acid (GABA) receptors. Because the
compositions permit
selective modulation of subtypes of GABA receptors, they are useful for
treating conditions in
which alteration of those receptor subtypes provides therapeutic benefit.
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Definitions
Definitions of specific functional groups and chemical terms are described in
more detail
below. The chemical elements are identified in accordance with the Periodic
Table of the
Elements, CAS version, Handbook of Chemistry and Physics, 75th Ed., inside
cover, and
specific functional groups are generally defined as described therein.
Additionally, general
principles of organic chemistry, as well as specific functional moieties and
reactivity, are
described in Thomas Sorrell, Organic Chemistry, University Science Books,
Sausalito, 1999;
Smith and March, March' s Advanced Organic Chemistry, 5th Edition, John Wiley
& Sons, Inc.,
New York, 2001; Larock, Comprehensive Organic Transformations, VCH Publishers,
Inc., New
York, 1989; and Carruthers, Some Modern Methods of Organic Synthesis, 3rd
Edition,
Cambridge University Press, Cambridge, 1987.
As used herein, a "pure isomeric" compound or "isomerically pure" compound is
substantially free of other isomers of the compound. The term "pure isomeric"
compound or
"isomerically pure" denotes that the compound comprises at least 95% by
weight, at least 96%
by weight, at least 97% by weight, at least 98% by weight, at least 99% by
weight, at least 99.5%
by weight, at least 99.6% by weight, at least 99.7% by weight, at least 99.8%
by weight, or at
least 99.9% by weight of the compound with the specified structure. In certain
embodiments, the
weights are based upon total weight of all isomers of the compound.
As used herein, a "pure stereoisomeric" compound or "stereoisomerically pure"
compound is substantially free of other stereoisomers of the compound. Thus,
the composition is
substantially free of isomers that differ at any chiral center. If the
compound has multiple chiral
centers, a substantial majority of the composition contains compounds having
identical
stereochemistry at all of the chiral centers. The term "pure stereoisomeric"
compound or
"stereoisomerically pure" denotes that the compound comprises at least 95% by
weight, at least
96% by weight, at least 97% by weight, at least 98% by weight, at least 99% by
weight, at least
99.5% by weight, at least 99.6% by weight, at least 99.7% by weight, at least
99.8% by weight,
or at least 99.9% by weight of the compound with the specified
stereochemistry. In certain
embodiments, the weights are based upon total weight of all stereoisomers of
the compound.
As used herein, a pure enantiomeric compound is substantially free from other
enantiomers or stereoisomers of the compound (i.e., in enantiomeric excess).
In other words, an
"S" form of the compound is substantially free from the "R" form of the
compound and is, thus,
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in enantiomeric excess of the "R" form. The term "enantiomerically pure" or
"pure enantiomer"
denotes that the compound comprises at least 95% by weight, at least 96% by
weight, at least
97% by weight, at least 98% by weight, at least 99% by weight, at least 99.5%
by weight, at least
99.6% by weight, at least 99.7% by weight, at least 99.8% by weight, or at
least 99.9% by weight
of the enantiomer. In certain embodiments, the weights are based upon total
weight of all
enantiomers or stereoisomers of the compound.
Compounds described herein may also comprise one or more isotopic
substitutions. For
example, H may be in any isotopic form, including 41, 2H (D or deuterium), and
3H (T or
tritium); C may be in any isotopic form, including '2C, '3C, and "C; N may be
any isotopic form,
including '41\T and '5N; 0 may be in any isotopic form, including 160 and 180;
and the like.
The articles "a" and "an" may be used herein to refer to one or to more than
one (i.e. at
least one) of the grammatical objects of the article. By way of example "an
analogue" means one
analogue or more than one analogue.
As used herein, the terms "modulation" and "potentiation" refer to the
inhibition or
stimulation of GABA receptor function. A "modulator" or "potentiator" may be,
for example, an
agonist, partial agonist, antagonist, or partial antagonist of the GABA
receptor. The "modulator"
or "potentiator" may act at the active site or at an allosteric site on a GABA
receptor. It may
promote or inhibit ligand binding. It may facilitate or attenuate ligand-
mediated, e.g., GABA-
mediated, signaling.
"Pharmaceutically acceptable" means approved or approvable by a regulatory
agency of
the Federal or a state government or the corresponding agency in countries
other than the United
States, or that is listed in the U.S. Pharmacopoeia or other generally
recognized pharmacopoeia
for use in animals, and more particularly, in humans.
"Pharmaceutically acceptable salt" refers to a salt of a compound of the
invention that is
pharmaceutically acceptable and that possesses the desired pharmacological
activity of the parent
compound. In particular, such salts are non-toxic may be inorganic or organic
acid addition salts
and base addition salts. Specifically, such salts include: (1) acid addition
salts, formed with
inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid,
nitric acid,
phosphoric acid, and the like; or formed with organic acids such as acetic
acid, propionic acid,
.. hexanoic acid, cyclopentanepropionic acid, glycolic acid, pyruvic acid,
lactic acid, malonic acid,
succinic acid, malic acid, maleic acid, fumaric acid, tartaric acid, citric
acid, benzoic acid, 3-(4-
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hydroxybenzoyl) benzoic acid, cinnamic acid, mandelic acid, methanesulfonic
acid,
ethanesulfonic acid, 1,2-ethane-disulfonic acid, 2-hydroxyethanesulfonic acid,
benzenesulfonic
acid, 4-chlorobenzenesulfonic acid, 2-naphthalenesulfonic acid, 4-
toluenesulfonic acid,
camphorsulfonic acid, 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; or (2) salts formed when an acidic proton present in the parent compound
either is replaced
by a metal ion, e.g., an alkali metal ion, an alkaline earth ion, or an
aluminum ion; or coordinates
with an organic base such as ethanolamine, diethanolamine, triethanolamine, N
methylglucamine
and the like. Salts further include, by way of example only, sodium,
potassium, calcium,
magnesium, ammonium, tetraalkylammonium, and the like; and when the compound
contains a
basic functionality, salts of non-toxic organic or inorganic acids, such as
hydrochloride,
hydrobromide, tartrate, mesylate, acetate, maleate, oxalate and the like. The
term
"pharmaceutically acceptable cation" refers to an acceptable cationic counter-
ion of an acidic
functional group. Such cations are exemplified by sodium, potassium, calcium,
magnesium,
ammonium, tetraalkylammonium cations, and the like. See, e.g., Berge, el al.,
J. Pharm. Sci.
(1977) 66(1): 1-79.
"Solvate" refers to forms of the compound that are associated with a solvent
or water
(also referred to as "hydrate"), usually by a solvolysis reaction. This
physical association
includes hydrogen bonding. Conventional solvents include water, ethanol,
acetic acid, and the
like. The compounds of the invention may be prepared e.g. in crystalline form
and may be
solvated or hydrated. Suitable solvates include pharmaceutically acceptable
solvates, such as
hydrates, and further include both stoichiometric solvates and non-
stoichiometric solvates. In
certain instances the solvate will be capable of isolation, for example when
one or more solvent
molecules are incorporated in the crystal lattice of the crystalline solid.
"Solvate" encompasses
both solution-phase and isolable solvates. Representative solvates include
hydrates, ethanolates
and methanolates.
As used herein, the term "isotopic variant" refers to a compound that contains
unnatural
proportions of isotopes at one or more of the atoms that constitute such
compound. For example,
an "isotopic variant" of a compound can contain one or more non-radioactive
isotopes, such as
for example, deuterium (2H or D), carbon-13 (13C), nitrogen-15 (15N), or the
like. It will be
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understood that, in a compound where such isotopic substitution is made, the
following atoms,
where present, may vary, so that for example, any hydrogen may be 2H/D, any
carbon may be
"C, or any nitrogen may be 15N, and that the presence and placement of such
atoms may be
determined within the skill of the art. Likewise, the invention may include
the preparation of
isotopic variants with radioisotopes, in the instance for example, where the
resulting compounds
may be used for drug and/or substrate tissue distribution studies. The
radioactive isotopes
tritium, i.e., 3H, and carbon-14, i.e., 14C, are particularly useful for this
purpose in view of their
ease of incorporation and ready means of detection. Further, compounds may be
prepared that
are substituted with positron emitting isotopes, such as "C,
and "N, and would be useful
in Positron Emission Topography (PET) studies for examining substrate receptor
occupancy. All
isotopic variants of the compounds provided herein, radioactive or not, are
intended to be
encompassed within the scope of the invention.
"Stereoisomers": It is also to be understood that compounds that have the same
molecular
formula but differ in the nature or sequence of bonding of their atoms or the
arrangement of their
atoms in space are termed "isomers." Isomers that differ in the arrangement of
their atoms in
space are termed "stereoisomers." Stereoisomers that are not mirror images of
one another are
termed "diastereomers", and those that are non-superimposable mirror images of
each other are
termed "enantiomers." When a compound has an asymmetric center, for example,
and an atom,
such as a carbon atom, is bonded to four different groups, a pair of
enantiomers is possible. An
enantiomer can be characterized by the absolute configuration of its
asymmetric center and is
described by the R- and S-sequencing rules of Cahn and Prelog, or by the
manner in which the
molecule rotates the plane of polarized light and designated as dextrorotatory
or levorotatory
(i.e., as (+) or (-)-isomers respectively). A chiral compound can exist as
either individual
enantiomer or as a mixture thereof A mixture containing equal proportions of
the enantiomers is
called a "racemic mixture".
"Tautomers" refer to compounds that are interchangeable forms of a particular
compound
structure, and that vary in the displacement of hydrogen atoms and electrons.
Thus, two
structures may be in equilibrium through the movement of n electrons and an
atom (usually H).
For example, enols and ketones are tautomers because they are rapidly
interconverted by
treatment with either acid or base. Another example of tautomerism is the aci-
and nitro- forms
of phenylnitromethane, that are likewise formed by treatment with acid or
base. Tautomeric
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forms may be relevant to the attainment of the optimal chemical reactivity and
biological activity
of a compound of interest.
A "subject" to which administration is contemplated includes, but is not
limited to, a
human (i.e., a male or female of any age group, e.g., a pediatric subject
(e.g., infant, child,
adolescent) or adult subject (e.g., young adult, middle-aged adult or senior
adult)) and/or a non-
human animal, e.g., a mammal such as primates (e.g., cynomolgus monkeys,
rhesus monkeys),
cattle, pigs, horses, sheep, goats, rodents, cats, and/or dogs. In certain
embodiments, the subject
is a human. In certain embodiments, the subject is a non-human animal.
Disease, disorder, and condition are used interchangeably herein.
As used herein, and unless otherwise specified, the terms "treat," "treating"
and
"treatment" contemplate an action that occurs while a subject is suffering
from the specified
disease, disorder or condition, which reduces the severity of the disease,
disorder or condition, or
retards or slows the progression of the disease, disorder or condition
("therapeutic treatment"),
and also contemplates an action that occurs before a subject begins to suffer
from the specified
disease, disorder or condition ("prophylactic treatment").
In general, the "effective amount" of a compound refers to an amount
sufficient to elicit
the desired biological response, e.g., to treat a CNS-related disorder, is
sufficient to induce
anesthesia or sedation. As will be appreciated by those of ordinary skill in
this art, the effective
amount of a compound of the invention may vary depending on such factors as
the desired
.. biological endpoint, the pharmacokinetics of the compound, the disease
being treated, the mode
of administration, and the age, weight, health, and condition of the subject.
An effective amount
encompasses therapeutic and prophylactic treatment.
As used herein, and unless otherwise specified, a "therapeutically effective
amount" of a
compound is an amount sufficient to provide a therapeutic benefit in the
treatment of a disease,
disorder or condition, or to delay or minimize one or more symptoms associated
with the disease,
disorder or condition. A therapeutically effective amount of a compound means
an amount of
therapeutic agent, alone or in combination with other therapies, which
provides a therapeutic
benefit in the treatment of the disease, disorder or condition. The term
"therapeutically effective
amount" can encompass an amount that improves overall therapy, reduces or
avoids symptoms
or causes of disease or condition, or enhances the therapeutic efficacy of
another therapeutic
agent.
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As used herein, and unless otherwise specified, a "prophylactically effective
amount" of a
compound is an amount sufficient to prevent a disease, disorder or condition,
or one or more
symptoms associated with the disease, disorder or condition, or prevent its
recurrence. A
prophylactically effective amount of a compound means an amount of a
therapeutic agent, alone
or in combination with other agents, which provides a prophylactic benefit in
the prevention of
the disease, disorder or condition. The term "prophylactically effective
amount" can encompass
an amount that improves overall prophylaxis or enhances the prophylactic
efficacy of another
prophylactic agent.
Compositions
Compounds
The invention provides compositions with isomerically pure forms of
neurosteroids.
In certain embodiments, the invention provides pharmaceutical compositions
containing
an isomerically pure form of a compound of Formula (I):
..--,
N. h
N
0,, .... j
H 1
f A i A
H (I).
The composition may be chemically pure, i.e., free from other molecules or
chemical
species. For example, the other molecule or chemical species may have a
distinct chemical
formula, structural formula, empirical formula, molecular formula, or
condensed formula. The
composition may have a defined level of chemical purity. For example, the
compound of
Formula (I) may be present at at least 95% by weight, at least 96% by weight,
at least 97% by
weight, at least 98% by weight, at least 99% by weight, at least 99.5% by
weight, at least 99.6%
by weight, at least 99.7% by weight, at least 99.8% by weight, or at least
99.9% by weight of the
.. total amount of a mixture that includes the compound of Formula (I) and one
or more distinct
molecules or chemical species.
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The composition may contain the compound of Formula (I) at any level of
isomeric
purity, i.e., the composition may contain the compound of Formula (I) at a
level in relation to an
isomeric form of the compound. For example, the compound of Formula (I) may be
present at at
least 95% by weight, at least 96% by weight, at least 97% by weight, at least
98% by weight, at
least 99% by weight, at least 99.5% by weight, at least 99.6% by weight, at
least 99.7% by
weight, at least 99.8% by weight, or at least 99.9% by weight of the total
amount of isomeric
molecules that include the compound of Formula (I) and an isomer thereof.
The composition may be isomerically pure with respect to all isomers. The
composition
may be isomerically pure with respect to one or more particular types of
isomers. The
composition may be substantially free of structural isomers or a particular
type of structural
isomers, such as a regioisomers. The composition may be substantially free of
stereoisomers or
a particular type of stereoisomers, such as enantiomers or diastereomers.
The composition may contain the compound of Formula (I) at any level of
isomeric
purity to achieve preferential modulation of an a4f336 GABAA receptor as
compared to an
a1f32y2 GABAA receptor. For example, the compound of Formula (I) may be
present at at least
95% by weight, at least 96% by weight, at least 97% by weight, at least 98% by
weight, at least
99% by weight, at least 99.5% by weight, at least 99.6% by weight, at least
99.7% by weight, at
least 99.8% by weight, or at least 99.9% by weight of the total amount of
isomeric molecules that
include the compound of Formula (I) and an isomer thereof.
The composition may contain the compound of Formula (I) and be substantially
free of
stereoisomers. The stereoisomer may differ from Formula (I) at one, two,
three, four, five, six,
seven, or eight chiral centers. The stereoisomer may be a diastereomer or an
enantiomer. For
example, the stereoisomer may be a compound of Formulas (II) or (III):
0
zõ
A
HO1 =
(II), and
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0õ,
. \ s
L 1-4
P4,-,. "'CM
õ
H i H
H
(III).
The composition may contain one or more stereoisomers of the compound of
Formula (I), such
as a compound of Formula (II) or (III), at less than 5%, less than 4%, less
than 3%, less than 2%,
less than 1%, less than 0.5%, or less than 0.1% of the total of the compound
of Formula (I) and
the one or more stereoisomers thereof. The composition may contain the
compound of Formula
(I) and one or more stereoisomer thereof at a ratio of at least 19:1,
20:1,25:1, 30:1,40:1, 50:1,
100:1, 200:1, 500:1, or 1000:1.
Formulations
The invention provides pharmaceutical compositions containing one or more of
the
compounds described above. A pharmaceutical composition containing the
compounds may be
in a form suitable for oral use, for example, as tablets, troches, lozenges,
fast-melts, aqueous or
oily suspensions, dispersible powders or granules, emulsions, hard or soft
capsules, syrups or
elixirs. Compositions intended for oral use may be prepared according to any
method known in
the art for the manufacture of pharmaceutical compositions and such
compositions may contain
one or more agents selected from sweetening agents, flavoring agents, coloring
agents and
preserving agents, in order to provide pharmaceutically elegant and palatable
preparations.
Tablets contain the compounds in admixture with non-toxic pharmaceutically
acceptable
excipients which are suitable for the manufacture of tablets. These excipients
may be for
example, inert diluents, such as calcium carbonate, sodium carbonate, lactose,
calcium phosphate
or sodium phosphate; granulating and disintegrating agents, for example corn
starch, or alginic
acid; binding agents, for example starch, gelatin or acacia, and lubricating
agents, for example
magnesium stearate, stearic acid or talc. The tablets may be uncoated or they
may be coated by
known techniques to delay disintegration in the stomach and absorption lower
down in the
gastrointestinal tract and thereby provide a sustained action over a longer
period. For example, a
time delay material such as glyceryl monostearate or glyceryl distearate may
be employed. They
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may also be coated by the techniques described in U.S. Patent Nos. 4,256,108;
4,166,452; and
4,265,874, the contents of which are incorporated herein by reference, to form
osmotic
therapeutic tablets for control release. Preparation and administration of
compounds is discussed
in U.S. Patent No. 6,214,841 and U.S. Pub. No. 2003/0232877, the contents of
which are
incorporated herein by reference.
Formulations for oral use may also be presented as hard gelatin capsules in
which the
compounds are mixed with an inert solid diluent, for example calcium
carbonate, calcium
phosphate or kaolin, or as soft gelatin capsules in which the compounds are
mixed with water or
an oil medium, for example peanut oil, liquid paraffin or olive oil.
An alternative oral formulation, where control of gastrointestinal tract
hydrolysis of the
compound is sought, can be achieved using a controlled-release formulation,
where a compound
of the invention is encapsulated in an enteric coating.
Aqueous suspensions may contain the compounds in admixture with excipients
suitable
for the manufacture of aqueous suspensions. Such excipients are suspending
agents, for example
sodium carboxymethylcellulose, methylcellulose, hydroxypropylmethylcellulose,
sodium
alginate, polyvinylpyrrolidone, gum tragacanth and gum acacia; dispersing or
wetting agents
such as a naturally occurring phosphatide, for example lecithin, or
condensation products of an
alkylene oxide with fatty acids, for example, polyoxyethylene stearate, or
condensation products
of ethylene oxide with long chain aliphatic alcohols, for example
heptadecaethyleneoxycetanol,
or condensation products of ethylene oxide with partial esters derived from
fatty acids and a
hexitol such a polyoxyethylene with partial esters derived from fatty acids
and hexitol
anhydrides, for example polyoxyethylene sorbitan monooleate. The aqueous
suspensions may
also contain one or more preservatives, for example ethyl, or n-propyl p-
hydroxybenzoate, one or
more coloring agents, one or more flavoring agents, and one or more sweetening
agents, such as
sucrose or saccharin.
Oily suspensions may be formulated by suspending the compounds in a vegetable
oil, for
example, arachis oil, olive oil, sesame oil or coconut oil, or in a mineral
oil such as liquid
paraffin. The oily suspensions may contain a thickening agent, for example
beeswax, hard
paraffin or cetyl alcohol. Sweetening agents such as those set forth above,
and flavoring agents
may be added to provide a palatable oral preparation. These compositions may
be preserved by
the addition of an anti-oxidant such as ascorbic acid.
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Dispersible powders and granules suitable for preparation of an aqueous
suspension by
the addition of water provide the compounds in admixture with a dispersing or
wetting agent,
suspending agent and one or more preservatives. Suitable dispersing or wetting
agents and
suspending agents are exemplified, for example sweetening, flavoring and
coloring agents, may
also be present.
The pharmaceutical compositions of the invention may also be in the form of
oil-in-water
emulsions. The oily phase may be a vegetable oil, for example olive oil or
arachis oil, or a
mineral oil, for example liquid paraffin or mixtures of these. Suitable
emulsifying agents may be
naturally-occurring gums, for example gum acacia or gum tragacanth, naturally
occurring
phosphatides, for example soya bean, lecithin, and esters or partial esters
derived from fatty acids
and hexitol anhydrides, for example sorbitan monooleate and condensation
products of the said
partial esters with ethylene oxide, for example polyoxyethylene sorbitan
monooleate. The
emulsions may also contain sweetening and flavoring agents.
Syrups and elixirs may be formulated with sweetening agents, such as glycerol,
propylene glycol, sorbitol or sucrose. Such formulations may also contain a
demulcent, a
preservative, and agents for flavoring and/or coloring. The pharmaceutical
compositions may be
in the form of a sterile injectable aqueous or oleaginous suspension. This
suspension may be
formulated according to the known art using those suitable dispersing or
wetting agents and
suspending agents which have been mentioned above. The sterile injectable
preparation may also
be in a sterile injectable solution or suspension in a non-toxic parenterally
acceptable diluent or
solvent, for example as a solution in 1,3-butanediol. Among the acceptable
vehicles and solvents
that may be employed are water, Ringer's solution and isotonic sodium chloride
solution. In
addition, sterile, fixed oils are conventionally employed as a solvent or
suspending medium. For
this purpose any bland fixed oil may be employed including synthetic mono- or
di-glycerides. In
addition, fatty acids such as oleic acid find use in the preparation of
injectables.
In certain embodiments, the formulation is not a sustained release
formulation. In certain
embodiments, the formulation is not injectable. In certain embodiments, the
formulation does
not contain particles having a D50 (volume weighted median diameter) of less
than 10 microns.
In certain embodiments, the formulation does not contain a polymer surface
stabilizer. In certain
embodiments, the formulation is not an aqueous suspension.
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The composition may be formulated for administration by a particular
mechanism. The
composition may be formulated for oral, intravenous, enteral, parenteral,
dermal, buccal, topical
nasal, or pulmonary administration. The composition may be formulated for
administration by
injection or on an implantable medical device (e.g., stent or drug-eluting
stent or balloon
equivalents).
The composition may be formulated a single daily dosage. The composition may
be
formulated for multiple daily dosages, e.g., two, three, four, five, six or
more daily dosages.
The composition may be provided to the subject according to any dosing
schedule. The
composition may be provide once per day. The composition may be provided
multiple times per
day. The composition may be provided two time, three times, four times, five
times, six times,
or more per day.
Treatment of GABAA receptor disorders
The compositions of the invention are useful for treating disorders that are
associated
with, or can be ameliorated by, alteration of activity of a GABAA receptor.
GABAA receptors
are ligand-gated ion channels that selectively allow Cl- ions to pass through
the plasma
membrane upon binding of GABA. GABAA receptors are expressed in neurons
throughout the
central nervous system (CNS) and mediate most of the physiological activities
of GABA in the
CNS. Within neurons, the type and density of GABAA receptors can vary between
cell bodies
and dendrites. GABAA receptors are also expressed in other tissues, including
Leydig cells,
placenta, immune cells, liver, bone growth plates, and other endocrine
tissues. Outside the CNS,
GABAA receptors can regulate cell proliferation and immune responses.
Structurally, GABAA receptors are pentamers that include five polypeptide
subunits. The
polypeptide subunits are encoded by 19 genes that are grouped as follows based
on sequence
similarity: a(1-6), 13(1-3), y(1-3), 6, 6, 0, n, and p(1-3). Most subtypes are
heteropentamers that
include two copies of one type of a subunit, two copies of one type of 13
subunit, and one copy of
one type of y, 6, 6, 0, or it subunit; other subtypes are homopentamers or
heteropentamers of p
subunits. Known subtypes of GABAA receptors include al f31y2, al f32y2, al
f33y2, a2f31y2,
a2f32y2, a2f33y2, a3f31y2, a3f32y2, a3f33y2, a4ply2, a4f336, a4f33y2, a5f31y2,
a5f32y2, a5f33y2,
a6f31y2, a6f32y2, and a6f33y2. GABAA receptor subtypes vary among tissue types
and
anatomical regions of the CNS, and subtypes may be associated with specific
functions. In
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addition, GABAA receptor subtypes may vary between normal and malignant cells
of the same
tissue type.
The active site of a GABAA receptor is the binding site for GABA and for drugs
such as
muscimol, gaboxadol, and bicuculline. GABAA receptors also have several
allosteric binding
sites that are the targets of other drugs, including benzodiazepines,
nonbenzodiazepines,
neuroactive steroids, barbiturates, ethanol, inhaled anaesthetics, and
picrotoxin. Thus, the
activity of GABAA receptors is controlled by binding of molecules to both the
active and
allosteric binding sites. The structure, function, and regulation of GABAA
receptors are known
in the art and described in, for example, Sigel E., and Steinmann, M.E.,
Structure, Function, and
Modulation of GABAA Receptors, J. Biol. Chem. 287:48 pp. 40224-402311 (2012),
doi:
10.1074/jbc.R112.386664, the contents of which are incorporated herein by
reference.
The isomerically pure compositions of the invention preferentially potentiate
the activity
selected GABAA receptor subtypes. The compositions of the invention may
preferentially
potentiate the activity of one or more GABAA receptor subtypes, such as those
described above,
relative to one or more GABAA receptor subtypes. In certain embodiments, the
compositions
preferentially potentiate the activity of a4f336 receptors compared to a1f32y2
receptors.
The compositions of the invention may potentiate one or more GABAA receptors
by any
mechanism. For example, and without limitation, the isomerically pure form a
compound may
potentiate a GABAA receptor by allosteric modulation, activation, or
inhibition. The allosteric
modulation may be positive or negative.
The preferential activity of a composition on one or more GABAA receptor as
compared
to one or more other GABAA receptor may be measured by any suitable means.
Activity may be
measure using in vitro assays or in vivo assays. For example and without
limitation, methods of
measuring the effect of modulators on GABAA receptor activity include
anticonvulsant assays,
binding assays, fluorescence membrane potential assays, immune response
assays, intracranial
self-stimulation assays patch clamps assays, proliferation assays receptor
occupancy assays
seizure induction assays, e.g., using pentylenetetrazol (PTZ) or maximal
electroshock (IYMS),
and survival assays. Such assays are known in the art and described in, for
example,
International Publication No. WO 2016/061527; Ghisdal P., et al., Determining
the relative
efficacy of positive allosteric modulators of the GABAA receptor: design of a
screening
approach, J Biomol Screen. 2014 Mar;19(3):462-7. doi:
10.1177/1087057113501555, Epub 2013
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Aug 29; Tian J., et al., Clinically applicable GABA receptor positive
allosteric modulators
promote B-cell replication, Sci Rep. 2017 Mar 23;7(1):374. doi: 10.1038/541598-
017-00515-y;
and Tian J., et al., A Clinically Applicable Positive Allosteric Modulator of
GABA Receptors
Promotes Human 13-Cell Replication and Survival as well as GABA's Ability to
Inhibit
Inflammatory T Cells, J Diabetes Res. 2019 Feb 26;2019:5783545, doi:
10.1155/2019/5783545,
the contents of each of which are incorporated herein by reference.
The preferential activity of a composition on one or more GABAA receptors as
compared
to one or more other GABAA receptors may be expressed by any suitable means.
For example
and without limitation, the preferential activity may be indicated by a
comparison of ECso values
or binding affinity values.
In certain embodiments, compositions of the invention have an ECso for a4036
GABAA
receptors that is lower than the ECso for a102y2 GABAA receptors. The ECso for
a4036 GABAA
receptors may be lower than the ECso for a102y2 GABAA receptors by about 2-
fold, about 3-
fold, about 4-fold, about 5-fold, about 6-fold, about 7-fold, about 8-fold,
about 10-fold, about 20-
fold, about 50-fold, about 100-fold, about 200-fold, about 500-fold, or about
1000-fold.
In certain embodiments, compositions of the invention have an ECso for a4036
GABAA
receptors that is less than about 50%, less than about 40%, less than about
30%, less than about
25%, less than about 20%, less than about 15%, less than about 10%, less than
about 5%, less
than about 4%, less than about 3%, less than about 2%, less than about 1%,
less than about 0.5%,
less than about 0.2%, or less than about 0.1% of the ECso for a102y2 GABAA
receptors.
In certain embodiments, compositions of the invention have an binding affinity
(which
may be expressed, e.g., as a dissociation constant KD) for a4036 GABAA
receptors that is lower
than the binding affinity for a102y2 GABAA receptors. The binding affinity for
a4036 GABAA
receptors may be lower than the binding affinity for a102y2 GABAA receptors by
about 2-fold,
about 3-fold, about 4-fold, about 5-fold, about 6-fold, about 7-fold, about 8-
fold, about 10-fold,
about 20-fold, about 50-fold, about 100-fold, about 200-fold, about 500-fold,
or about 1000-fold.
In certain embodiments, compositions of the invention have an binding affinity
for a4036
GABAA receptors that is less than about 50%, less than about 40%, less than
about 30%, less
than about 25%, less than about 20%, less than about 15%, less than about 10%,
less than about
5%, less than about 4%, less than about 3%, less than about 2%, less than
about 1%, less than
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about 0.5%, less than about 0.2%, or less than about 0.1% of the binding
affinity for al f32y2
GABAA receptors.
In certain embodiments, compositions of the invention have an ECso for a4f336
GABAA
receptors that is below a defined value. For example and without limitation,
the composition
may have an ECso for a4f336 GABAA receptors that is less than about 1 less
than about 500
nM, less than about 400 nM, less than about 300 nM, less than about 200 nM,
less than about
100 nM, less than about 50 nM, less than about 25 nM, less than about 10 nM,
less than about 5
nM, less than about 2.5 nM, less than about 1 nM, less than about 0.5 nM, less
than about 0.25
nM, or less than about 0.1 nM.
In certain embodiments, compositions of the invention have an binding affinity
for a4f336
GABAA receptors below a defined value. For example and without limitation, the
composition
may have an binding affinity for a4f336 GABAA receptors that is less than
about 1 tM, less than
about 500 nM, less than about 400 nM, less than about 300 nM, less than about
200 nM, less
than about 100 nM, less than about 50 nM, less than about 25 nM, less than
about 10 nM, less
than about 5 nM, less than about 2.5 nM, less than about 1 nM, less than about
0.5 nM, less than
about 0.25 nM, or less than about 0.1 nM.
The compositions and methods of the invention may be effective for treatment
of a
GABAA disorder. The GABAA disorder may be any disease, disorder, or condition
associated
with altered GABAA receptor function or any disorder may be disease, disorder,
or condition that
can be ameliorated by altered GABAA receptor function. The GABAA disorder may
be acute
pain, an addictive disorder, Alzheimer's disease, Angelman's syndrome, anti-
social personality
disorder, an anxiety disorder, attention deficit hyperactivity disorder
(ADHD), an attention
disorder, an auditory disorder, autism, an autism spectrum disorder, bipolar
disorder, chronic
pain, a cognitive disorder, a compulsive disorder, a convulsive disorder,
dementia, depression,
dysthymia, an epileptic disorder, essential tremor, epileptogenesis, fragile X
syndrome,
generalized anxiety disorder (GAD), Huntington's disease, injury related pain
syndrome,
insomnia, ischemia, Lewis body type dementia, a memory disorder, migraines, a
mood disorder,
movement disorder, a neurodegenerative disease, neuropathic pain, an obsessive
compulsive
disorder, pain, a panic disorder, Parkinson's disease, a personality disorder,
posttraumatic stress
disorder (PTSD), psychosis, Rett syndrome, a schizoaffective disorder,
schizophrenia, a
schizophrenia spectrum disorder, a seizure disorder, a sleep disorder, social
anxiety disorder,
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status epilepticus, stress, stroke, tinnitus, traumatic brain injury (TBI),
vascular disease, vascular
malformation, vascular type dementia movement disorder, Wilson's disease, or
withdrawal
syndrome.
The methods of treating a subject include providing a composition of the
invention, as
described above, to the subject. Providing may include administering the
composition to the
subject. The composition may be administered by any suitable means, such as
orally,
intravenously, enterally, parenterally, dermally, buccally, topically
(including transdermally), by
injection, nasally, pulmonarily, and with or on an implantable medical device
(e.g., stent or drug-
eluting stent or balloon equivalents). Preferably, the composition is provided
orally.
The composition may be provided under any suitable dosing regimen. For
example, the
composition may be provided as a single dose or in multiple doses. Multiple
doses may be
provided in provided separated by intervals, such as 4 hours, 6 hours, 8
hours, 12 hours, 24
hours, 2 days, 3 days, 4 days, 5 days, 1 week, 2 weeks, 3 weeks, 4 weeks, or
more. Multiple
doses may be provided within a period of time. For example, multiple doses may
be provided
over a period of 1 day, 2 days, 3 days, 4 days, 5 days, 1 week, 2 weeks, 3
weeks, 4 weeks, or
more. The compositions may be provided repeatedly for a specified duration.
For example and
without limitation, the compositions may be provided for 1 week, 2 weeks, 3
weeks, 4 weeks, 6
weeks, 8 weeks, 12 weeks, 3 months, 4 months, 5 months, 6 months, 8 months, 10
months, 12
months or more.
Examples
Example 1
The ability of CV-10155 and SPNC-019 to modulate the activity of GABAA
receptors of
different GABAA was analyzed. CV-10155 and SPNC-019 have the following
structures:
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...,,,õ,,, .:..n....0
, !I
, d
0>
\
1
1
/
H ------------------------ /
......,,.õ .:, ,
H CV-10155, and
0
=----*\
N----k
\ ,
1 H - N,',.\)'''''CN
HOvi., -,----;,-,,,
H H
. z
H
SPNC-019.
Cells expressing the indicated GABAA receptor subtype were exposed to gamma-
aminobutyric acid in the presence of varying concentrations of either CV-10155
or SPNC-019,
calcium flux was measured using a fluorometric imaging plate reader (FLIPR),
and EC50 values
for compounds were determined. Results are provided in Table 1.
Table 1.
---------------------------------------------------- ,
GABAA EC50 (M)
Compound CV-10155 SPNC-019
a1f31y2 5.21E-07 --
a1f32y2 8.39E-07 --
al f33y2 5.20E-07 --
a2f31y2 2.53E-07 --
a2f32y2 2.13E-07 --
a2f33y2 2.96E-07 --
a3f31y2 9.46E-07 --
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GABAA EC50 (M)
Compound CV-10155 SPNC-019
a3f32y2 1.82E-06
a3f33y2 2.73E-07
a4f31y2 2.04E-07
a4f336 1.06E-07
a4f33y2 1.33E-06
a5f31y2 7.62E-07
a5f32y2 3.59E-07 1.198e-006
a5f33y2 1.30E-06 1.805e-006
a6f31y2 3.59E-07
a6f32y2 1.10E-06
a6f33y2 2.45E-07 1.766e-006
-- value not measurable
CV-10155 showed some level of positive allosteric modulating activity in all
of the
GABAA receptor subtypes tested. In contrast, SPNC-019 had no modulating
activity in 15 of the
18 GABAA receptor subtypes tested. The only structural difference between CV-
10155 and
SPNC-019 is the stereochemical configuration of the hydroxyl and methyl groups
attached to the
carbon atom at position 3 of the steroid core. Thus, the results show that a
change in the
stereochemistry of a single chiral center of a steroid-based compound
dramatically alters ability
of the molecule to modulate GABAA receptor activity. The results further
indicate that the
isomeric purity of neurosteroid compositions greatly impacts the utility of
such compositions as
therapeutic agents.
Example 2
The ability of various neurosteroids to compete with t-
butylbicyclophosphorothionate
(TBPS), a ligand for the picrotoxin binding site of GABAA receptors, was
analyzed in
International Publication No. WO 2016/061527. WO 2016/061527, pages 215-227.
Compounds
were assayed for binding to GABA receptors in membranes isolated from the
cortices of rat
brains. WO 2016/061527, page 216.
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Among the neurosteroids analyzed was Compound 10, which has the following
structure:
0
H
HD R, t
WO 2016/061527, page 106. Compound 10 is identical to the structure of Formula
(II) and is a
stereoisomer of the structure of Formula (I). Compound 10/Formula (II) and
Formula (I) are
stereoisomers that differ only in the configuration of the hydrogen atom
bonded to the carbon
atom at position 5: Compound 10/Formula (II) has a 5f3 configuration, whereas
Formula (I) has
a 5a configuration.
Another neurosteroid analyzed in WO 2016/061527 was Compound 121, which has
the
following structure:
(re
j
R
WO 2016/061527, page 150. Compound 121 is a regioisomer of the structure of
Formula (I).
Compound 121 and Formula (I) differ only in the positioning of the cyano
substituent on the
pyrazole ring: Compound 121 is substituted at the 3 position of the pyrazole
ring, whereas
Formula (I) is substituted at the 4 position of the pyrazole ring.
Compound 10 and Compound 121 are isomers that have two structural differences:
the
stereochemical configuration at carbon 5, and the position of the cyano
substituent on the
pyrazole ring.
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Results of the analysis are provided in Table 1 of WO 2016/061527. WO
2016/061527,
pages 217-227. Compound 10 has an ICso of <10 nM in the TBPS displacement
assay, whereas
Compound 121 has an ICso of 10-50 nM. WO 2016/061527, pages 217 and 221.
These results show that subtle structural differences in a neurosteroid can
drastically
affect binding of the molecule to GABAA receptors.
Example 3
The pharmacological efficacy of various neurosteroids for a1f32y2 GABAA
receptors and
a4f336 GABAA receptors and was analyzed in International Publication No. WO
2016/061527.
WO 2016/061527, pages 227-231. Compounds were tested for the ability to
modulate GABA-
mediated currents at a submaximal dose of agonist in LTK cells stably
transfected with a1f32y2
subunits and in CHO cells transiently transfected with a4f336 subunits WO
2016/061527, pages
227-228. Cells were incubated with GABA at 2 tM, which is the EC2o for GABA,
and 0.01
0.1 tM, 1 tM, or 10 tM neurosteroid. WO 2016/061527, pages 227-228.
Results of the analysis are provided in Table 2 of WO 2016/061527. WO
2016/061527,
pages 229-231. Results are presented as the relative potentiation of GABA-
mediated
conductance in the presence of 10 tM neurosteroid compared to GABA-mediated
conductance
in the absence of neurosteroid. WO 2016/061527, page 228. Compound 121 at 10
tM
displayed an efficacy of >500% for both a1f32y2 GABAA receptors and a4f336
GABAA
receptors. WO 2016/061527, page 229.
The results show that a regioisomer of Formula (I) displays no preferential
modulation of
a4f336 GABAA receptors over a1f32y2 GABAA receptors. In particular, a compound
that differs
from Formula (I) only by the positioning of the cyano substituent on the
pyrazole ring has
comparable efficacy on the two GABAA receptor subtypes. Thus, the data give no
indication
that compositions containing a compound of Formula (I) can preferentially
modulate a4f336
GABAA receptors over a1f32y2 GABAA receptors or that such compositions can be
administered
at concentrations that modulate a4f336 GABAA receptors but not a1f32y2 GABAA
receptors.
Consequently, nothing from the results suggests that compositions containing
the compound of
Formula (I) would be useful for treatment of conditions in which potentiation
of a4f336 GABAA
receptors but not a1f32y2 GAB AA receptors is beneficial.
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In contrast, the data provided in Example 1 show that the compound of Formula
(I) is
substantially more active on a4f336 GABAA receptors than on a1f32y2 GABAA
receptors. Taken
together, the results in the Examples demonstrate that subtle structural
differences in a
neurosteroid affect the ability of the molecule to potentiate specific
subtypes of GABAA
receptors. Therefore, it follows from the results that the isomeric purity of
neurosteroid
compositions can influence receptor subtype specificity and thus the utility
of such compositions
as therapeutic agents.
Incorporation by Reference
References and citations to other documents, such as patents, patent
applications, patent
publications, journals, books, papers, web contents, have been made throughout
this disclosure.
All such documents are hereby incorporated herein by reference in their
entirety for all purposes.
Equivalents
Various modifications of the invention and many further embodiments thereof,
in
addition to those shown and described herein, will become apparent to those
skilled in the art
from the full contents of this document, including references to the
scientific and patent literature
cited herein. The subject matter herein contains important information,
exemplification, and
guidance that can be adapted to the practice of this invention in its various
embodiments and
equivalents thereof.
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