The present disclosure is generally directed to neuroactive 13,17-substituted steroids as referenced herein, and pharmaceutically acceptable salts thereof, for use as, for example, an anesthetic, and/or in the treatment of disorders relating to GABA function and activity. The present disclosure is further directed to pharmaceutical compositions comprising such compounds.

BACKGROUND OF THE DISCLOSURE

The present disclosure is generally directed to novel compounds having utility as an anesthetic and/or in the treatment of disorders relating to GABA function and activity. More specifically, the present disclosure is directed to steroids having a 13,17-substituted tetracyclic structure that are neuroactive and suitable for use as an anesthetic, as well as pharmaceutically acceptable salts thereof, and pharmaceutical compositions containing them.

Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter of the central nervous system. GABA activates two types of receptors, the inotropic GABAAand the metabotropic GABABreceptor. Activation of the GABABreceptor by GABA causes hyperpolarization and a resultant inhibition of neurotransmitter release. The GABAAreceptor subtype regulates neuronal excitability and rapid mood changes, such as anxiety, panic, and stress response. GABAAreceptors are chloride ion channels; as a result, activation of the receptor induces increased inward chloride ion flux, resulting in membrane hyperpolarization and neuronal inhibition. Drugs that stimulate GABAAreceptors, such as benzodiazepines and barbiturates, have anticonvulsive effects (by reducing neuronal excitability and raising the seizure threshold), as well as anxiolytic and anesthetic effects.

The effect of certain steroids on GABAAreceptors has been well-established. As a result, researchers continue to pursue the discovery and synthesis of neuroactive steroids that may act as anesthetics and/or that may serve to provide treatment for disorders related to GABA function. For example, it is now widely accepted that the intravenous anesthetic alphaxalone (Compound A, below) causes general anesthesia in humans because it allosterically increases chloride currents mediated by GABA acting at GABAAreceptors in the brain. However, the various structural features that enable this compound to function in the way it does have, to-date, not been fully understood. For example, in contrast to alphaxalone, Δ16-alphaxalone (Compound B, below), has been observed to have greatly diminished allosteric activity at GABAAreceptors and is not used as an intravenous general anesthetic in humans.

The difference in performance of these two compounds, which some have attributed to the presence of the carbon-carbon double bond in the D-ring, has attracted the attention of many researchers. In fact, recently, it was determined that the effect this double bond has on anesthetic activity may depend on the group attached at C-17 on the D-ring. (See Bandyopadhyaya, A. K., et al., “Neurosteroid analogues. 15. A comparative study of the anesthetic and GABAergic actions of alphaxalone, Δ16-alphaxalone and their corresponding 17-carbonitrile analogues. Bioorg. Med. Chem. Lett., 20: 6680-4 (2010).)

In addition to anesthetic properties, neuroactive steroids may be used to treat disorders related to GABA function. For example, neuroactive steroids, such as progesterone, may be used as sedative-hypnotics, exhibiting benzodiazepine-like actions, inducing reduced sleep latency and increased non-REM sleep with only small changes in slow wave and REM sleep. Further, drugs that enhance GABA responses are often used to treat anxiety in humans. Thus, it might be expected that GABA-potentiating steroids would exhibit anxiolytic effects. Neuroactive steroids may also be used to treat depression, given that accumulating evidence suggests that patients with major depression have decreased levels of GABAergic neurosteroids and that certain treatments for depression alter levels of these steroids. Although GABA is not typically thought to play a critical role in the biology of depression, there is evidence that low GABAergic activity may predispose one to mood disorders. Finally, inhibition of NMDA receptors and enhancement of GABAAreceptors appear to play important roles in mediating the acute effects of ethanol in the nervous system, while related studies suggest that GABAergic neurosteroids may be involved in some of the pharmacological effects of ethanol and that neuroactive steroids may be useful in treating ethanol withdrawal.

In view of the foregoing, it is clear that there are a number of potentially advantageous uses for neurosteroids. As a result, there is a continuing need for the further synthesis and understanding of new neuroactive steroids, particularly those having utility as an anesthetic and/or in the treatment of a disorder relating to GABA function and activity.

SUMMARY OF THE DISCLOSURE

In one aspect, the present disclosure is directed to a compound having a structure of Formula (I):

or a pharmaceutically acceptable salt thereof;

- - - denotes an optional, additional C—C bond, resulting in either a C═C bond between C4-C5or C5-C6, with the proviso that when present, the C5—H substituent is not present.

The present disclosure is still further directed to a pharmaceutical composition comprising a therapeutically effective amount of one or more of the above-noted steroids or pharmaceutically acceptable salts thereof, and optionally a pharmaceutically acceptable carrier. The present disclosure also provides kits comprising steroids, salts thereof, and/or pharmaceutical compositions thereof.

The present disclosure further provides methods of inducing anesthesia in a subject in need thereof, the method comprising administering to the subject a therapeutically effective amount of one or more of the above-noted steroids, or pharmaceutically acceptable salts thereof, or a pharmaceutical composition thereof.

The present disclosure further provides methods of treating disorders related to GABA function in a subject in need thereof, the method comprising administering to the subject a therapeutically effective amount of one or more of the above-noted steroids, or pharmaceutically acceptable salts thereof, or a pharmaceutical composition thereof. In certain embodiments, the disorder is selected from the group consisting of insomnia, mood disorders, convulsive disorders, Fragile X syndrome, anxiety, or symptoms of ethanol withdrawal.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

In accordance with the present disclosure, it has been discovered that compounds having certain 13,17-substituted steroid structures are neuroactive and are also suitable for use as anesthetics and in the treatment of disorders associated with GABA function, as well as pharmaceutically acceptable salts thereof. The compounds may be used, for example, as an effective continuous infusion sedative for non-surgical procedures (e.g., colonoscopy). The compounds also offer advantages over anesthetics known in the art, such as a lower likelihood for bacterial contamination, as well as an improved relationship with solubilizing agents.

Generally speaking, the steroid of the present disclosure has a tetracyclic, fused ring structure, such as a cyclopenta[a]phenanthrene ring system (an embodiment of which is illustrated and discussed in greater detail below), wherein the C3-position of the A ring has a hydroxyl or an ester substituent in the alpha configuration, the C13position has a substituent attached thereto in the beta configuration selected from the group consisting of optionally substituted C2-C4alkenyl, optionally substituted C2-C4alkynyl, optionally substituted cyclopropyl, and C(O)Rz, where Rzis C1-C4alkyl, C2-C4alkenyl or C2-C4alkynyl; and the C17-position of the D ring has a substituent attached thereto in the beta configuration selected from the group consisting of H, optionally substituted C1-C4alkyl, optionally substituted C2-C4alkenyl, optionally substituted alkynyl, cyclopropyl, and C(O)Ry, where Ryis C1-C4alkyl, C2-C4alkenyl or C2-C4alkynyl.

More particularly, however, the present disclosure is directed, in certain embodiments, to a steroid having the structure of Formula (I):

or a pharmaceutically acceptable salt thereof;

- - - denotes an optional, additional C—C bond, resulting in either a C═C bond between C4-C5or C5-C6, with the proviso that when present, the C5—H substituent is not present.

As generally defined above, R1is H, optionally substituted C1-C4alkyl, optionally substituted C2-C4alkenyl, or optionally substituted C2-C4alkynyl. In a preferred embodiment, R1is H. R1is in the beta configuration.

As generally defined above, R5is H, ═O, or ORv, where Rvis H, optionally substituted C1-C4alkyl, optionally substituted C2-C4alkenyl, optionally substituted C2-C4alkynyl, or optionally substituted aryl. In a preferred embodiment, R5is H. In another preferred embodiment, R5is alkoxy (e.g., —OCH3). R5can be in either the beta configuration or the alpha configuration.

As generally defined above, R6is H, optionally substituted C1-C4alkyl, optionally substituted C2-C4alkenyl, or optionally substituted C2-C4alkynyl. In a preferred embodiment, R6is methyl. In another preferred embodiment, R6is substituted alkyl, and more particularly is alkoxy-substituted alkyl (e.g., —CH2OCH3). R6is in the beta configuration.

As generally defined above, R8, when present (e.g., when R5is not ═O), is H, C1-C4alkyl, C2-C4alkenyl, or C2-C4alkynyl. In a preferred embodiment, R8is H.

As generally defined above, R9is H or C(O)Ru, where Ruis optionally substituted C1-C20alkyl, optionally substituted C2-C20alkenyl, or optionally substituted C2-C20alkynyl. In certain embodiments, Ruis optionally substituted C1-C15alkyl, C1-C10alkyl, or C1-C4alkyl. In other certain embodiments, Ruis optionally substituted C1-C15alkenyl, C1-C10alkenyl, or C1-C4alkenyl. In yet other certain embodiments, Ruis optionally substituted C1-C15alkynyl, C1-C10alkynyl, or C1-C4alkynyl. In a preferred embodiment, R9is H. The OR9substituent is in the alpha configuration.

As generally defined above, - - - denotes an optional, additional C—C bond, resulting in either a C═C bond between C4-C5or C5-C6, with the proviso that when present, the C5—H substituent is not present. In certain embodiments, the additional C—C bond is absent, and the hydrogen at C5is in the alpha or beta configuration. In a preferred embodiment, the additional C—C bond is absent, and the hydrogen at C5is in the alpha configuration. In certain embodiments, - - - denotes an additional C—C bond, resulting in a C═C bond between C4-C5. In certain embodiments, - - - denotes an additional C—C bond, resulting in a C═C bond between C5-C6.

It is to be noted that the present disclosure contemplates and is intended to encompass all of the various combinations and permutations (i.e., combinations of substituent options, locations and stereochemical configurations) possible here.

For example, in various embodiments, compounds of the present disclosure have the formula of (I-a):

As generally defined above in Formula (I-a), R3is H, optionally substituted CrC4alkyl, optionally substituted C2-C4alkenyl, optionally substituted alkynyl, cyclopropyl, or C(O)Ry, where Ryis C1-C4alkyl, C2-C4alkenyl or C2-C4alkynyl. In certain embodiments, R3is —CH═CH2. In other certain embodiments, R3is ethyl. In yet other certain embodiments, R3is C(O)CH3. In certain embodiments, R3is hydroxyl alkyl. In a preferred embodiment, R3is C(OH)CH3. In yet another preferred embodiment, R3is CH2(OH). In other certain embodiments, R3is haloalkyl. In a preferred embodiment, R3is CH2Cl. R3is in the beta configuration.

As generally defined above in Formula (I-a), R4is optionally substituted C2-C4alkenyl, optionally substituted C2-C4alkynyl, optionally substituted cyclopropyl, or C(O)Rz, where Rzis C1-C4alkyl, C2-C4alkenyl or C2-C4alkynyl. In certain embodiments, R4is —CH═CH2. In other certain embodiments, R4is C(O)CH3. R4is in the beta configuration.

Accordingly, as noted, the steroid of Formulas (I) and (I-a) may encompass a number of various structures in accordance with the present disclosure, including all of the various combinations and permutations (i.e., combinations of substituent options, locations and stereochemical configurations) possible here

Exemplary compounds of Formula (I) include, but are not limited to:

and pharmaceutically acceptable salts thereof.

In this regard it is to be noted that the structures provided above are of various exemplary embodiments. As such, they should not be viewed in a limiting sense.

3. Methods of Preparation and Pharmaceutical Compositions

It is to be noted that the compounds or steroids of the present disclosure, may in various embodiments be prepared or used in accordance with means generally known in the art. For example, in certain embodiments, the steroids of the present disclosure may be prepared or used in a pharmaceutically acceptable salt form. Suitable salt forms include, for example, citrate or chloride salt forms.

In various embodiments of the present disclosure, a pharmaceutical composition is disclosed that may comprise a steroid or a combination of two or more thereof in accordance with the formulas of the present disclosure. The compounds or steroids of the present disclosure, as well as the various salt forms and other pharmaceutically acceptable forms, e.g., solvates and/or hydrates of compounds described herein, and pharmaceutical compositions containing them, may in general be prepared using methods and techniques known in the art, and/or as described in the Examples provided herein.

Without wishing to be bound by any particular theory, the compounds or steroids of the present disclosure are useful for potentiating GABA at GABAAreceptors thereby inducing anesthesia or treating disorders related to GABA function (e.g., insomnia, mood disorders, Fragile X syndrome, convulsive disorders, anxiety disorders, or symptoms of ethanol withdrawal) in a subject, e.g., a human subject, and are preferably administered in the form of a pharmaceutical composition comprising an effective amount of a compound of the instant disclosure and optionally a pharmaceutically or pharmacologically acceptable carrier.

In one aspect, provided is a method of inducing anesthesia in a subject in need thereof, the method comprising administering to the subject a therapeutically effective amount of one or more of the above-noted steroids or pharmaceutically acceptable salts thereof, or a pharmaceutical composition thereof.

In another aspect, provided is a method of treating disorders related to GABA function in a subject in need thereof, the method comprising administering to the subject a therapeutically effective amount of one or more of the above-noted steroids or pharmaceutically acceptable salts thereof, or a pharmaceutical composition thereof. In certain embodiments, the disorder is selected from the group consisting of insomnia, mood disorders, convulsive disorders, Fragile X syndrome, anxiety, or symptoms of ethanol withdrawal.

In one embodiment of the present disclosure, a therapeutically effective amount of compound is from about 5 mg/kg to about 20 mg/kg, about 5 mg/kg to about 18 mg/kg, about 5 mg/kg to about 16 mg/kg, about 5 mg/kg to about 14 mg/kg, about 5 mg/kg to about 12 mg/kg, about 5 mg/kg to about 10 mg/kg, about 6 mg/kg to about 10 mg/kg, about 6 mg/kg to about 9 mg/kg, about 7 mg/kg to about 9 mg/kg, or about 8 mg/kg to about 16 mg/kg. In certain embodiments, a therapeutically effective amount of the compound is about 8 mg/kg. It will be appreciated that dose ranges as described herein provide guidance for the administration of provided pharmaceutical compositions to an adult. The amount to be administered to, for example, a child or an adolescent can be determined by a medical practitioner or person skilled in the art and can be lower or the same as that administered to an adult.

The exact amount of a compound required to achieve an effective amount will vary from subject to subject, depending, for example, on species, age, and general condition of a subject, identity of the particular compound(s), mode of administration, and the like. The desired dosage can be delivered three times a day, two times a day, once a day, every other day, every third day, every week, every two weeks, every three weeks, or every four weeks. In certain embodiments, the desired dosage can be delivered using multiple administrations (e.g., two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, or more administrations). In other certain embodiments, the compound may be administered via continuous intravenous (IV) infusion, such as used by those commonly skilled in the art of general anesthesia.

It will be also appreciated that a compound or composition, as described herein, can be administered in combination with one or more additional therapeutically active agents. The compounds or compositions can be administered in combination with additional therapeutically active agents that improve their bioavailability, reduce and/or modify their metabolism, inhibit their excretion, and/or modify their distribution within the body.

The compound or composition can be administered concurrently with, prior to, or subsequent to, one or more additional therapeutically active agents. In general, each agent will be administered at a dose and/or on a time schedule determined for that agent. It will further be appreciated that the additional therapeutically active agent utilized in this combination can be administered together in a single composition or administered separately in different compositions. The particular combination to employ in a regimen will take into account compatibility of the inventive compound with the additional therapeutically active agent and/or the desired therapeutic effect to be achieved. In general, it is expected that additional therapeutically active agents utilized in combination be utilized at levels that do not exceed the levels at which they are utilized individually. In some embodiments, the levels utilized in combination will be lower than those utilized individually. Exemplary therapeutically active agents include small organic molecules such as drug compounds (e.g., compounds approved by the US Food and Drug Administration as provided in the Code of Federal Regulations (CFR)), peptides, proteins, carbohydrates, monosaccharides, oligosaccharides, polysaccharides, nucleoproteins, mucoproteins, lipoproteins, synthetic polypeptides or proteins, small molecules linked to proteins, glycoproteins, steroids, nucleic acids, DNAs, RNAs, nucleotides, nucleosides, oligonucleotides, antisense oligonucleotides, lipids, hormones, vitamins and cells.

The pharmaceutical composition may also be in combination with at least one pharmacologically acceptable carrier. The carrier, also known in the art as an excipient, vehicle, auxiliary, adjuvant, or diluent, is any substance that is pharmaceutically inert, confers a suitable consistency or form to the composition, and does not diminish the therapeutic efficacy of the compounds. The carrier is “pharmaceutically or pharmacologically acceptable” if it does not produce an adverse, allergic, or other untoward reaction when administered to a mammal or human, as appropriate.

The pharmaceutical compositions containing the compounds or steroids of the present disclosure may be formulated in any conventional manner. Proper formulation is dependent upon the route of administration chosen. The compositions of the disclosure can be formulated for any route of administration, so long as the target tissue is available via that route. Suitable routes of administration include, but are not limited to, oral, parenteral (e.g., intravenous, intraarterial, subcutaneous, rectal, subcutaneous, intramuscular, intraorbital, intracapsular, intraspinal, intraperitoneal, or intrasternal), topical (nasal, transdermal, intraocular), intravesical, intrathecal, enteral, pulmonary, intralymphatic, intracavital, vaginal, transurethral, intradermal, aural, intramammary, buccal, orthotopic, intratracheal, intralesional, percutaneous, endoscopical, transmucosal, sublingual, and intestinal administration. In certain embodiments, the route of administration is oral. In certain embodiments, the route of administration is parenteral. In certain embodiments, the route of administration is intravenous.

Pharmaceutically acceptable carriers for use in the compositions of the present disclosure are well known to those of ordinary skill in the art and are selected based upon a number of factors, including for example: the particular compound used, and its concentration, stability and intended bioavailability; the disease, disorder or condition being treated with the composition; the subject, its age, size and general condition; and/or the route of administration. Suitable carriers may be readily determined by one of ordinary skill in the art. (See, for example, J. G. Nairn, in: Remington's Pharmaceutical Science (A. Gennaro, ed.), Mack Publishing Co., Easton, Pa., (1985), pp. 1492-1517.)

The compositions may be formulated as tablets, dispersible powders, pills, capsules, gelcaps, caplets, gels, liposomes, granules, solutions, suspensions, emulsions, syrups, elixirs, troches, dragees, lozenges, or any other dosage form that can be administered orally. Techniques and compositions for making oral dosage forms useful in the present disclosure are described in the following exemplary references: 7 Modern Pharmaceutics, Chapters 9 and 10 (Banker & Rhodes, Editors, 1979); Lieberman et al., Pharmaceutical Dosage Forms: Tablets (1981); and, Ansel, Introduction to Pharmaceutical Dosage Forms 2nd Edition (1976).

The compositions of the present disclosure designed for oral administration comprise an effective amount of a compound of the disclosure in a pharmaceutically acceptable carrier. Suitable carriers for solid dosage forms include sugars, starches, and other conventional substances including lactose, talc, sucrose, gelatin, carboxymethylcellulose, agar, mannitol, sorbitol, calcium phosphate, calcium carbonate, sodium carbonate, kaolin, alginic acid, acacia, corn starch, potato starch, sodium saccharin, magnesium carbonate, tragacanth, microcrystalline cellulose, colloidal silicon dioxide, croscarmellose sodium, talc, magnesium stearate, and stearic acid. Further, such solid dosage forms may be uncoated or may be coated by known techniques (e.g., to delay disintegration and absorption).

The compounds and steroids of the present disclosure may also be formulated for parenteral administration (e.g., formulated for injection via intravenous, intraarterial, subcutaneous, rectal, subcutaneous, intramuscular, intraorbital, intracapsular, intraspinal, intraperitoneal, or intrasternal routes). The compositions of the present disclosure for parenteral administration comprise an effective amount of the compound in a pharmaceutically acceptable carrier. Dosage forms suitable for parenteral administration include solutions, suspensions, dispersions, emulsions or any other dosage form that can be administered parenterally. Techniques and compositions for making parenteral dosage forms are known in the art. Typically formulations for parenteral administration are sterile or are sterilized before administration.

Suitable carriers used in formulating liquid dosage forms for oral or parenteral administration include nonaqueous, pharmaceutically-acceptable polar solvents such as oils, alcohols, amides, esters, ethers, ketones, hydrocarbons and mixtures thereof, as well as water, saline solutions, dextrose solutions (e.g., DW5), electrolyte solutions, or any other aqueous, pharmaceutically acceptable liquid.

Additional minor components can be included in the compositions of the disclosure for a variety of purposes well known in the pharmaceutical industry. These components will for the most part impart properties which enhance retention of the compound at the site of administration, protect the stability of the composition, control the pH, facilitate processing of the compound into pharmaceutical formulations, and the like. Preferably, each of these components is individually present in less than about 15 wt % of the total composition, more preferably less than about 5 wt %, and most preferably less than about 0.5 wt % of the total composition. Some components, such as fillers or diluents, can constitute up to 90 wt % of the total composition, as is well known in the formulation art. Such additives include cryoprotective agents for preventing reprecipitation, surface active, wetting or emulsifying agents (e.g., lecithin, polysorbate-80, Tween® 80, Pluronic 60, polyoxyethylene stearate), preservatives (e.g., ethyl-p-hydroxybenzoate), microbial preservatives (e.g., benzyl alcohol, phenol, m-cresol, chlorobutanol, sorbic acid, thimerosal and paraben), agents for adjusting pH or buffering agents (e.g., acids, bases, sodium acetate, sorbitan monolaurate), agents for adjusting osmolarity (e.g., glycerin), thickeners (e.g., aluminum monostearate, stearic acid, cetyl alcohol, stearyl alcohol, guar gum, methyl cellulose, hydroxypropylcellulose, tristearin, cetyl wax esters, polyethylene glycol), colorants, dyes, flow aids, non-volatile silicones (e.g., cyclomethicone), clays (e.g., bentonites), adhesives, bulking agents, flavorings, sweeteners, adsorbents, fillers (e.g., sugars such as lactose, sucrose, mannitol, or sorbitol, cellulose, or calcium phosphate), diluents (e.g., water, saline, electrolyte solutions), binders (e.g., starches such as maize starch, wheat starch, rice starch, or potato starch, gelatin, gum tragacanth, methyl cellulose, hydroxypropyl methylcellulose, sodium carboxymethyl cellulose, polyvinylpyrrolidone, sugars, polymers, acacia), disintegrating agents (e.g., starches such as maize starch, wheat starch, rice starch, potato starch, or carboxymethyl starch, cross-linked polyvinyl pyrrolidone, agar, alginic acid or a salt thereof such as sodium alginate, croscarmellose sodium or crospovidone), lubricants (e.g., silica, talc, stearic acid or salts thereof such as magnesium stearate, or polyethylene glycol), coating agents (e.g., concentrated sugar solutions including gum arabic, talc, polyvinyl pyrrolidone, carbopol gel, polyethylene glycol, or titanium dioxide), and antioxidants (e.g., sodium metabisulfite, sodium bisulfite, sodium sulfite, dextrose, phenols, and thiophenols).

Dosage from administration by these routes may be continuous or intermittent, depending, for example, upon the patient's physiological condition, whether the purpose of the administration is therapeutic or prophylactic, and other factors known to and assessable by a skilled practitioner.

Those with ordinary skill in administering anesthetics can readily determine dosage and regimens for the administration of the pharmaceutical compositions of the disclosure or titrating to an effective dosage for use in treating insomnia, mood disorders, convulsive disorders, anxiety or symptoms of ethanol withdrawal. It is understood that the dosage of the compounds will be dependent upon the age, sex, health, and weight of the recipient, kind of concurrent treatment, if any, frequency of treatment, and the nature of the effect desired. For any mode of administration, the actual amount of compound delivered, as well as the dosing schedule necessary to achieve the advantageous effects described herein, will also depend, in part, on such factors as the bioavailability of the compound, the disorder being treated, the desired therapeutic dose, and other factors that will be apparent to those of skill in the art. The dose administered to an animal, particularly a human, in the context of the present disclosure should be sufficient to affect the desired therapeutic response in the animal over a reasonable period of time. Preferably, an effective amount of the compound, whether administered orally or by another route, is any amount that would result in a desired therapeutic response when administered by that route. The dosage may vary depending on the dosing schedule, which can be adjusted as necessary to achieve the desired therapeutic effect. The most preferred dosage will be tailored to the individual subject, as is understood and determinable by one of ordinary skill in the art without undue experimentation.

In one embodiment, solutions for oral administration are prepared by dissolving the compound in any pharmaceutically acceptable solvent capable of dissolving a compound (e.g., ethanol or methylene chloride) to form a solution. An appropriate volume of a carrier which is a solution, such as beta-hydroxypropyl-cyclodextrin, is added to the solution while stirring to form a pharmaceutically acceptable solution for oral administration to a patient. If desired, such solutions can be formulated to contain a minimal amount of, or to be free of, ethanol, which is known in the art to cause adverse physiological effects when administered at certain concentrations in oral formulations.

In another embodiment, powders or tablets for oral administration are prepared by dissolving a compound in any pharmaceutically acceptable solvent capable of dissolving the compound (e.g., ethanol or methylene chloride) to form a solution. The solvent can optionally be capable of evaporating when the solution is dried under vacuum. An additional carrier can be added to the solution prior to drying, such as beta-hydroxypropyl-cyclodextrin. The resulting solution is dried under vacuum to form a glass. The glass is then mixed with a binder to form a powder. The powder can be mixed with fillers or other conventional tabletting agents and processed to form a tablet for oral administration to a patient. The powder can also be added to any liquid carrier as described above to form a solution, emulsion, suspension or the like for oral administration.

Emulsions for parenteral administration can be prepared by dissolving a compound in any pharmaceutically acceptable solvent capable of dissolving the compound (e.g., ethanol or methylene chloride) to form a solution. An appropriate volume of a carrier which is an emulsion, such as Liposyn® II or Liposyn® III emulsions, is added to the solution while stirring to form a pharmaceutically acceptable emulsion for parenteral administration to a patient.

Solutions for parenteral administration can be prepared by dissolving a compound in any pharmaceutically acceptable solvent capable of dissolving the compound (e.g., ethanol or methylene chloride) to form a solution. An appropriate volume of a carrier which is a solution, such as beta-hydroxypropyl-cyclodextrin, is added to the solution while stirring to form a pharmaceutically acceptable solution for parenteral administration to a patient.

If desired, the emulsions or solutions described above for oral or parenteral administration can be packaged in IV bags, vials or other conventional containers in concentrated form and diluted with any pharmaceutically acceptable liquid, such as saline, to form an acceptable concentration prior to use as is known in the art.

Still further encompassed by the disclosure are kits (e.g., pharmaceutical packs). The kits provided may comprise a compound as described herein and a container (e.g., a vial, ampule, bottle, syringe, and/or dispenser package, or other suitable container). In some embodiments, provided kits may optionally further include a second container comprising a pharmaceutical carrier for dilution or suspension of the pharmaceutical composition or compound. In some embodiments, the pharmaceutical composition or compound provided in the container and the second container are combined to form one unit dosage form.

Optionally, instructions for use are additionally provided in such kits of the disclosure. Such instructions may provide, generally, for example, instructions for dosage and administration. In other embodiments, instructions may further provide additional detail relating to specialized instructions for particular containers and/or systems for administration. Still further, instructions may provide specialized instructions for use in conjunction and/or in combination with an additional therapeutic agent.

The term “steroid” as used herein describes an organic compound containing in its chemical nucleus the cyclopenta[a]phenanthrene ring system.

As used herein, a “subject” to which administration is contemplated includes, but is not limited to, mammals, e.g., humans (i.e., a male or female of any age group, e.g., a pediatric subject (e.g., child, adolescent) or adult subject (e.g., young adult, middle-aged adult or senior adult)), other primates (e.g., cynomolgus monkeys, rhesus monkeys) and commercially relevant mammals such as cattle, pigs, horses, sheep, goats, cats, and/or dogs. In any aspect and/or embodiment of the disclosure, the subject is a human.

As used herein, a “therapeutically effective amount” “an amount sufficient” or “sufficient amount” of a compound means the level, amount or concentration of the compound required for a desired biological response, e.g., analgesia.

The term “saturated” as used herein describes the state in which all available valence bonds of an atom (especially carbon) are attached to other atoms.

The term “unsaturated” as used herein describes the state in which not all available valence bonds along the alkyl chain are satisfied; in such compounds the extra bonds usually form double or triple bonds (chiefly with carbon).

As used herein, “alkyl” refers to a radical of a straight-chain or branched saturated hydrocarbon group having from, in some embodiments, 1 to 4 carbon atoms (“C1-4alkyl”), and in other embodiments 1 to 22 carbon atoms (“C1-22alkyl”). In some embodiments, an alkyl group has 1 to 3 carbon atoms (“C1-3alkyl”). In some embodiments, an alkyl group has 1 to 2 carbon atoms (“C1-2alkyl”). In some embodiments, an alkyl group has 1 carbon atom (“C1alkyl”). In some embodiments, an alkyl group has 2 to 4 carbon atom (“C2-4alkyl”). In yet other embodiments, an alkyl group has 1 to 21 carbon atoms (“C1-21alkyl”), 1 to 20 carbon atoms (“C1-20alkyl”), 1 to 15 carbon atoms (“C1-15alkyl”), 1 to 10 carbon atoms (“C1-10alkyl”), etc. Examples of such alkyl groups include methyl (C1), ethyl (C2), n-propyl (C3), isopropyl (C3), n-butyl (C4), tert-butyl (C4), sec-butyl (C4), iso-butyl (C4), pentyl (C5), and the like.

As used herein, “alkenyl” or “alkene” refers to a radical of a straight-chain or branched hydrocarbon group having from, in some embodiments, 2 to 4 carbon atoms (“C2-4alkenyl”), and in other embodiments 2 to 22 carbon atoms (“C2-22alkenyl”), and one or more carbon-carbon double bonds. In some embodiments, an alkenyl group has 2 to 3 carbon atoms (“C2-3alkenyl”). In some embodiments, an alkenyl group has 2 carbon atoms (“C2alkenyl”). In yet other embodiments, an alkenyl group has 2 to 21 carbon atoms (“C2-21alkenyl”), 2 to 20 carbon atoms (“C2-20alkenyl”), 2 to 15 carbon atoms (“C2-15alkenyl”), 2 to 10 carbon atoms (“C2-10alkyl”), etc. The one or more carbon-carbon double bonds can be internal (such as in 2-butenyl) or terminal (such as in 1-butenyl). Examples of such alkenyl groups include ethenyl (C2), 1-propenyl (C3), 2-propenyl (C3), 1-butenyl (C4), 2-butenyl (C4), butadienyl (C4), 1-pentenyl (C5), 2-pentenyl (C5), and the like.

As used herein, “alkynyl” or “alkyne” refers to a radical of a straight-chain or branched hydrocarbon group having from 2 to 4 carbon atoms and one or more carbon-carbon triple bonds (“C2-10alkynyl”). In some embodiments, an alkynyl group has 2 to 3 carbon atoms (“C2-3alkynyl”). In some embodiments, an alkynyl group has 2 carbon atoms (“C2alkynyl”). The one or more carbon-carbon triple bonds can be internal (such as in 2-butynyl) or terminal (such as in 1-butynyl). Examples of C2-4alkynyl groups include, without limitation, ethynyl (C2), 1-propynyl (C3), 2-propynyl (C3), 1-butynyl (C4), 2-butynyl (C4), and the like.

As used herein, “aryl” refers to a radical of a monocyclic or polycyclic (e.g., bicyclic or tricyclic) 4n+2 aromatic ring system (e.g., having 6, 10, or 14 electrons shared in a cyclic array) having 6-14 ring carbon atoms and zero heteroatoms provided in the aromatic ring system (“C6-14aryl”). In some embodiments, an aryl group has 6 ring carbon atoms (“C6aryl”; e.g., phenyl). In some embodiments, an aryl group has 10 ring carbon atoms (“C10aryl”; e.g., naphthyl such as 1-naphthyl and 2-naphthyl). In some embodiments, an aryl group has 14 ring carbon atoms (“C1-4aryl”; e.g., anthracyl).

As used herein, “alkoxy” refers to an alkyl, alkenyl, or alkynyl group, as defined herein, attached to an oxygen radical.

Alkyl, alkenyl, alkynyl, and aryl groups, as defined herein, are substituted or unsubstituted, also referred to herein as “optionally substituted”. In general, the term “substituted”, whether preceded by the term “optionally” or not, means that at least one hydrogen present on a group (e.g., a carbon or nitrogen atom) is replaced with a permissible substituent, e.g., a substituent which upon substitution results in a stable compound, e.g., a compound which does not spontaneously undergo transformation such as by rearrangement, cyclization, elimination, or other reaction. Unless otherwise indicated, a “substituted” group has a substituent at one or more substitutable positions of the group, and when more than one position in any given structure is substituted, the substituent is either the same or different at each position. The term “substituted” is contemplated to include substitution with all permissible substituents of organic compounds, any of the substituents described herein that result in the formation of a stable compound. The present disclosure contemplates any and all such combinations in order to arrive at a stable compound. For purposes of this disclosure, heteroatoms such as nitrogen may have hydrogen substituents and/or any suitable substituent as described herein which satisfy the valencies of the heteroatoms and results in the formation of a stable moiety.

EXAMPLES

The following Examples describe or illustrate various embodiments of the present disclosure. Other embodiments within the scope of the appended claims will be apparent to a skilled artisan considering the specification or practice of the disclosure as described herein. It is intended that the specification, together with the Examples, be considered exemplary only, with the scope and spirit of the disclosure being indicated by the claims, which follow the Example.

Compound Chemistry

In accordance with the following methods and Examples, the following compounds were prepared using methods known in the industry.

In accordance with Scheme 1, the following compounds were prepared, using methods generally known in the art and as outlined below.

Compound 1 was prepared as described previously (see, e.g., Qian, et al., “Neurosteroid Analogues, 18. Structure-Activity Studies of ent-Steroid Potentiators of γ-Aminobutyric Acid Type A Receptors and Comparison of Their Activities with Those of Alphaxalone and Allopregnanolone,” J. of Med. Chem., Vol. 57(1), pages 171-190 (2014)).

To a solution of compound 4 (300 mg, 0.79 mmol) in cyclohexane (50 mL) maintained at reflux by irradiation with a high intensity tungsten lamp were added iodine (345 mg, 2.7 mmol) and lead tetraacetate (1.35 g, 3 mmol)) and the mixture was allowed to reflux for 80 min. One more portion of lead tetraacetate (0.75 g, 1.7 mmol) was added and reflux was continued for another 50 minutes. The hot cyclohexane solution was filtered through a pad of celite and the filtrate was collected. The filter cake was washed with EtOAc and the washings were collected. The combined filtrate and washings were concentrated to give a brown solution containing some particulate material. Solvents were removed and the crude product was dissolved in acetone and stirred at room temperature. Jones reagent was added dropwise until an orange color persisted. The excess Jones reagent was consumed by adding few drops of 2-propanol and the solution was diluted with water and the product extracted into EtOAc. The extract was washed with brine, dried and concentrated to give a colorless oil which was purified by flash column chromatography (silica gel eluted with 15-25% EtOAc in hexanes) to give to give compound 5 an oil (150 mg, 48%). IR vmax2931, 1760, 1447, 1370, 1236 cm−1;1H NMR (CDCl3) δ 4.66 (apparent q, 2H, J=6.7 Hz), 4.30 (dd, 1H, J=9.0 Hz, J=5.1 Hz) 4.06 (d, 1H, J=9.0 Hz), 3.76 (s, 1H), 3.39 (s, 1H), 3.36 (s, 3H), 3.30 (s, 3H), 0.99 (s, 3H), 0.93 (m, 1H) 0.75 (m, 1H);13C NMR (CDCl3) δ 179.5, 95.3, 78.9, 73.5, 72.2, 56.5, 55.33, 55.28, 54.2, 53.4, 45.2, 39.6, 36.2, 35.8, 32.9, 32.3, 31.7, 31.4, 29.7, 27.9, 27.3, 20.2, 13.1.

Compound 6 (65 mg, 0.16 mmol) was stirred in a DMSO (4 mL) solution of iodoxybenzoic acid (622 mg, 45% by weight, 1 mmol) at room temperature for 3 h. Water was added and the product extracted into EtOAc. The extract was washed with brine, dried and concentrated to give an oil which was purified by filtering through a short silica gel column eluted with 30% ethyl acetate hexanes to yield compound 7 which was dissolved in THF and kept at 0° C. and immediately converted without characterization (1H NMR confirmed the presence of the aldehyde group) to compound 8.

In accordance with Scheme 2, the following compounds were prepared, using methods generally known in the art and as outlined below.

To a solution of compound 13 (5.6 g, 12.8 mmol) in THF (45 mL) was added BH3.THF (26 mL, 1 M solution in THF) the reaction was stirred at 0° C. for 3 h. Then 30% hydrogen peroxide (35 mL) and 5 M aqueous NaOH (35 mL) was carefully added at 0° C. and stirring was continued at room temperature for 3 h. Water (200 mL) was added and the extracted into EtOAc. The extract was washed with brine, dried and concentrated to give a viscous liquid. The crude product was purified by flash column chromatography (silica gel eluted with 20-35% EtOAc in hexanes) to give a mixture of the 5α-reduced 6α-alcohol and the 5β-reduced 6β-alcohol (4.7 g, 80%) which was oxidized immediately without any further characterization.

Compound 24 was prepared from compound 23 using the procedure described for the preparation of compound 7 from compound 6. Compound 24 was immediately converted without characterization (1H NMR confirmed the presence of the aldehyde group) to compound 25.

In accordance with Scheme 3, the following compounds were prepared, using methods generally known in the art and as outlined below.

Compound 27 was prepared as described previously (see Bandyopadhyaya, et al., “Neurosteroid analogues. 15. A comparative study of the anesthetic and GABAergic actions of alphaxalone, Δ16-alphaxalone and their corresponding 17-carbonitrile analogues,” Bioorganic & Medicinal Chemistry Letters, Vol. 20(22), pages 6680-6684 (2010)).

Compound 34 was prepared from compound 33 using the procedure described for the preparation of compound 7 from compound 6. Compound 34 was immediately converted without characterization to compound 35.

In accordance with Scheme 4, the following compounds were prepared, using methods generally known in the art and as outlined below.

Compound 46 was prepared from compound 45 using the procedure described for the preparation of compound 7 from compound 6. Compound 34 was immediately converted without characterization to compound 47.

In accordance with Scheme 5, the following compounds were prepared, using methods generally known in the art and as outlined below.

Compound 49 is commercially available and was purchased from the Sigma-Aldrich Chemical Co. (St. Louis, Mo.).

Compound 50 was prepared as described previously (see, Ruzicka, et al., “Steroids and sex hormones. CXXXIX. The relation between constitution and odor of steroids. Methylandrostane and allopregnane derivatives,” Helvetica Chimica Acta, Vol. 30, pages 867-878 (1947)).

Compound 54 (330 mg, 0.87 mmol) in DMSO (1 mL) was added to the solution of iodoxybenzoic acid (400 mg, 1.43 mmol) in DMSO (2.5 mL) and stirred at room temperature for 90 min. Water (30 mL) was added and the precipitate obtained by filtration was washed thoroughly with EtOAc. The EtOAc filtrate was washed with water and dried. The solvent was removed and the residue was purified by flash column chromatography (silica gel eluted with hexanes/EtOAc, 7:1) to give compound 55 (300 mg, 91%) as a mixture of 17α- and 17β-carboxaldehydes in the ratio of 1:4 which was used without further separation or purification.

In accordance with Scheme 6, the following compounds were prepared, using methods generally known in the art and as outlined below.

In accordance with Scheme 7, the following compounds were prepared, using methods generally known in the art and as outlined below.

In accordance with Scheme 8, the following compounds were prepared, using methods generally known in the art and as outlined below.

In accordance with Scheme 9, the following compounds were prepared, using methods generally known in the art and as outlined below.

In accordance with Scheme 10, the following compounds were prepared, using methods generally known in the art and as outlined below.

The commercially available steroid (3α,5α)-3-hydroxypregnan-2-one (1 g, 3.14 mmol) was dissolved in stirred CH2Cl2(20 mL) and methoxymethychloride (0.75 mL) was added. The reaction was cooled to 0° C. and diisopropylethylamine (2.6 mL) was added and stirring was continued at 0° C. for 1.5 h and then at room temperature overnight. Aqueous NH4Cl was added and the product extracted into CH2Cl2. The CH2Cl2was washed with brine, dried and the solvent removed. The crude product (1.58 g) was purified by flash column chromatography (silica gel eluted with 20% EtOAc in hexanes to give the intermediate (3α,5α)-3-[[(1,1-Dimethylethyl)dimethylsilyl]oxy]-pregnan-20-one (1.01 g) which was reduced to a mixture of the 20R and 20S alcohols by NaBH4(added in four portions) in MeOH (30 mL) and THF (10 mL) at −5° C. to 0° C. The reaction time was 1 h. The solvent was removed, water was added and the product extracted into EtOAc. The EtOAc was dried and removed and the 20R and 20S alcohols (˜4:1 ratio, 1 g) were purified and separated by flash column chromatography (silica gel eluted with 5-30% EtOAc in hexanes) to give pure product 74 (0.84 g) as a white solid which had:1H NMR (CDCl3) δ 4.66 (m, 2H), 3.82 (m, 1H), 3.72 (m, 1H), 3.37 (s, 3H), 2.03 (m, 1H), 1.12 (d, 3H, J=6.3 Hz), 0.79 (s, 3H), 0.74 (s, 3H).

Compound 75 (240 mg crude containing compound 74) was prepared from compound 74 using the procedure described for the preparation of compound 67 from compound 59. Compound 75 was not characterized.

The IC60values for non-competitive displacers of [35S]-TBPS from the picrotoxin binding site on GABAAreceptors are reported in Table 1.

Results presented are from duplicate experiments performed in triplicate. Error limits are calculated as standard error of the mean. Methods used are known in the art (see Jiang, X., et al., Neurosteroid analogues. 9. Conformationally constrained pregnanes: structure-activity studies of 13,24-cyclo-18,21-dinorcholane analogues of the GABA modulatory and anesthetic steroids (3α,5α)- and (3α,5α)-3-hydroxypregnan-20-one. J. Med. Chem., 46: 5334-48 (2003)—the contents of which are hereby incorporated by reference in their entirety).

Electrophysiology Results

The compounds of the present disclosure were evaluated for the ability to potentiate chloride currents mediated by 2 μM GABA at rat α1β2γ2Ltype GABAAreceptors expressed inXenopus laevisoocytes and the results are shown in Table 2.

aThe GABA concentration used for the control response was 2 μM. Each compound was evaluated on at least four different oocytes at the concentrations indicated, and the results reported are the ratio of currents measured in the presence/absence of added compound. Gating represents direct current gated by 10 μM compound in the absence of GABA, and this current is reported as the ratio of compound only current/2 μM GABA current. Error limits are calculated as standard error of the mean (N≧4). Methods used are known in the art (see Jiang, X., et al.).

Tadpole Loss of Righting and Swimming

Table 3 discloses the anesthetic effects of the compounds of the present disclosure. In particular, the anesthetic effect of the compounds of the present disclosure on Loss of Righting Reflex (LRR) and Loss of Swimming Reflex (LSR).

Methods used are known in the art (see Jiang, X., et al.). Error limits are calculated as standard error of the mean (N=10 or more animals at each of five or more different concentrations).

General Methods

The compounds discussed in the present disclosure were produced as discussed elsewhere throughout this disclosure and by the following methods.

Solvents were either used as purchased or dried and purified by standard methodology. Extraction solvents were dried with anhydrous Na2SO4and after filtration, removed on a rotary evaporator. Flash chromatography was performed using silica gel (32-63 μm) purchased from Scientific Adsorbents (Atlanta, Ga.). Melting points were determined on a Kofler micro hot stage and are uncorrected. FT-IR spectra were recorded as films on a NaCl plate. NMR spectra were recorded in CDCl3at ambient temperature at 300 MHz (1H) or 74 MHz (13C). Purity was determined by TLC on 250 μm thick Uniplates™ from Analtech (Newark, Del.). All pure compounds (purity >95%) gave a single spot on TLC. Elemental analyses were performed by M-H-W Laboratories (Phoenix, Ariz.).

EQUIVALENTS AND SCOPE

In view of the above, it will be seen that the several advantages of the disclosure are achieved and other advantageous results attained. As various changes could be made in the above processes and composites without departing from the scope of the disclosure, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

When introducing elements of the present disclosure or the various versions, embodiment(s) or aspects thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. It is also noted that the terms “comprising”, “including”, “having” or “containing” are intended to be open and permits the inclusion of additional elements or steps.