Polymorphs of PN6047 hydrochloride

Abstract

This invention relates to the hydrochloride salt of 4-[(3-carbamoylphenyl)[1-(1,3-thiazolyl-5-ylmethyl)piperidin-4-ylidene]methyl]-N,N-dimethylbenzamide (PN6047) and its crystalline forms, more particularly to the HCl2 and HCl3 forms of PN6047. The invention also relates to pharmaceutical compositions comprising such polymorphs, methods for preparing such polymorphs, and the use of such polymorphs in the treatment or prevention of conditions mediated by the agonist effect of δ-opioid receptors, particularly in the treatment or prevention of pain.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Swedish Patent Application No. 2050910-5, filed on July 17, 2020, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] This invention relates to the hydrochloride salt of 4-[(3-carbamoylphenyl)[1-(1,3-thiazolyl-5-ylmethyl)piperidin-4-ylidene]methyl]-N,N-dimethylbenzamide (PN6047) and its crystalline forms, more particularly to the HCl2 and HCl3 forms of PN6047. The invention also relates to pharmaceutical compositions comprising such polymorphs, methods for preparing such polymorphs, and the use of such polymorphs in the treatment or prevention of conditions mediated by the agonist effect of δ-opioid receptors, particularly in the treatment or prevention of pain. Background Technology

[0004] WO 2016 / 099393 discloses compound 4-[(3-carbamoylphenyl)[1-(1,3-thiazolyl-5-ylmethyl)piperidin-4-ylidene]methyl]-N,N-dimethylbenzamide (PN6047; structure shown below). It is a potent delta-opioid receptor agonist that maintains analgesic efficacy after repeated administration. Compared to existing analgesics that only provide moderate pain relief, PN6047 has the potential to produce sustained analgesia in painful states and reduce the risk of adverse side effects such as respiratory depression and constipation.

[0005]

[0006] For use in pharmaceutical formulations, it is desirable for the active pharmaceutical ingredient (API) to be in a highly crystalline form. Amorphous (i.e., non-crystalline) materials may contain high levels of residual solvents, which is undesirable. Furthermore, amorphous materials may exhibit faster decomposition and may spontaneously form crystals with variable crystallinity due to their lower chemical and physical stability compared to crystalline materials. This can lead to non-reproducible solubility and difficulties in storing and handling the material. Therefore, there is a need for a crystalline form of PN6047 with improved properties in terms of stability, batch handling, and solubility. In particular, an object of the present invention is to provide a stable crystalline form of PN6047 that exhibits high solubility, contains low levels of residual solvents, has high chemical stability and low hygroscopicity, and can achieve a high level of crystallinity. Attached Figure Description

[0007] Figure 1 The X-ray powder diffraction pattern of HCl2 is shown.

[0008] Figure 2 The X-ray powder diffraction pattern of the HCl3 form is shown.

[0009] Figure 3 The temperature curves from the thermal cycling experiment are shown.

[0010] Figure 4 Displaying a differential scanning calorimetry (DSC) thermal analysis graph of HCl2.

[0011] Figure 5 The DSC thermal analysis chromatogram of HCl3 is shown.

[0012] Figure 6 Thermogravimetric analysis (TGA) and heat flow pyrometry plots for the HCl2 form are shown.

[0013] Figure 7 The TGA and heat flow pyrometry diagrams for the HCl3 form are shown.

[0014] Figure 8 Display the dynamic vapor adsorption (DVS) isotherm plot for HCl2.

[0015] Figure 9 The DVS isotherm plot in HCl3 form is shown. Detailed Implementation

[0016] The hydrochloride (HCl) salt of PN6047 has been found to have certain advantages over the free alkali compound, including improved solubility in water at room temperature and increased bioavailability. It has also been found that the HCl salt of PN6047 can exist in different crystalline or polymorphic forms. Some of these crystalline forms exhibit good solubility, good chemical and physical stability (including solution stability), and low hygroscopicity, and are therefore suitable for use in pharmaceutical compositions of PN6047. Therefore, in a first aspect, the present invention relates to the HCl salt of PN6047. In some embodiments, the HCl salt is a crystalline salt.

[0017] In some embodiments, the present invention provides a crystalline HCl salt of PN6047 that is stable at a temperature of 25°C and a relative humidity (RH) of up to 60%. In some embodiments, the present invention provides a crystalline HCl salt of PN6047 that is stable at a temperature of 40°C and a relative humidity of up to 75%. Such a crystalline HCl salt is stable under these conditions for at least 1 day, 1 week, 1 month, 3 months, 6 months, 1 year, 2 years, 3 years, or even longer.

[0018] In one embodiment, the crystalline HCl salt of PN6047 is in the HCl2 form. This form can be prepared by crystallization from certain organic solvents such as 2-propanol, acetone, acetonitrile, ethanol, ethyl acetate, or tetrahydrofuran. In one embodiment, the HCl2 form has an X-ray powder diffraction (XRPD) pattern obtained by CuKα1-irradiation, the XRPD pattern having peaks at least at °2θ values ​​of 16.5±0.2, 23.3±0.2, and 23.5±0.2. In some embodiments, the HCl2 form has an XRPD pattern obtained by CuKα1-irradiation, the XRPD pattern having peaks at at least one or more of the following °2θ values: 16.5±0.2, 23.3±0.2, and 23.5±0.2, and °2θ values ​​of 14.3±0.2, 16.1±0.2, 16.3±0.2, and 20.2±0.2. In some embodiments, the HCl2 form has an XRPD spectrum obtained by CuKα1- radiation, the XRPD spectrum having peaks at least at °2θ values ​​of 14.3±0.2, 16.1±0.2, 16.3±0.2, 16.5±0.2, 20.2±0.2, 23.3±0.2 and 23.5±0.2. In some embodiments, the HCl2 form has an XRPD spectrum obtained by CuKα1- radiation, the XRPD spectrum having peaks at least at one or more of the following °2θ values: 14.3±0.2, 16.1±0.2, 16.3±0.2, 16.5±0.2, 20.2±0.2, 23.3±0.2, and 23.5±0.2, and °2θ values: 15.2±0.2, 18.5±0.2, 19.4±0.2, 20.4±0.2, 24.0±0.2, 24.8±0.2, and 26.9±0.2. In some embodiments, the HCl₂ form has an XRPD spectrum obtained by CuKα₁⁻ radiation, the XRPD spectrum having peaks at least at °2θ values ​​of 14.3±0.2, 15.2±0.2, 16.1±0.2, 16.3±0.2, 16.5±0.2, 18.5±0.2, 19.4±0.2, 20.2±0.2, 20.4±0.2, 23.3±0.2, 23.5±0.2, 24.0±0.2, 24.8±0.2, and 26.9±0.2. In a particular embodiment, the present invention relates to an HCl₂ form having an XRPD spectrum obtained by CuKα₁⁻ radiation, the XRPD spectrum being substantially as follows: Figure 1 As shown.

[0019] In another embodiment, the crystalline HCl salt of PN6047 is in the HCl3 form. This form can be separated by evaporating water from an aqueous solution, crystallizing from acetonitrile, or by subjecting the amorphous HCl salt of PN6047 to 40°C / 75% RH. The HCl3 form is believed to be a hydrate. In one embodiment, the HCl3 form has an XRPD spectrum obtained by CuKα-irradiation, the XRPD spectrum having peaks at least at °2θ values ​​of 12.8±0.2, 19.1±0.2, and 23.9±0.2. In some embodiments, the HCl3 form has an XRPD spectrum obtained by CuKα-irradiation, the XRPD spectrum having peaks at at least one or more of the °2θ values ​​of 12.8±0.2, 19.1±0.2, and 23.9±0.2, and °2θ values ​​of 10.0±0.2, 25.3±0.2, and 26.3±0.2. In some embodiments, the HCl3 form has an XRPD spectrum obtained by CuKα-irradiation, the XRPD spectrum having peaks at least at °2θ values ​​of 10.0±0.2, 12.8±0.2, 19.1±0.2, 23.9±0.2, 25.3±0.2, and 26.3±0.2. In some embodiments, the HCl3 form has an XRPD spectrum obtained by CuKα-irradiation, the XRPD spectrum having peaks at at least one or more of the following °2θ values: 10.0±0.2, 12.8±0.2, 19.1±0.2, 23.9±0.2, 25.3±0.2, and 26.3±0.2, and °2θ values ​​of 14.5±0.2, 16.2±0.2, 18.3±0.2, 20.8±0.2, 27.4±0.2, and 29.7±0.2. In some embodiments, the HCl3 form has an XRPD spectrum obtained by CuKα-irradiation, said XRPD spectrum having peaks at least at °2θ values ​​of 10.0±0.2, 12.8±0.2, 14.5±0.2, 16.2±0.2, 18.3±0.2, 19.1±0.2, 20.8±0.2, 23.9±0.2, 25.3±0.2 and 26.3±0.2, 27.4±0.2 and 29.7±0.2. In a particular embodiment, the present invention relates to the HCl3 form having an XRPD spectrum obtained by CuKα-irradiation, said XRPD spectrum being substantially as follows: Figure 2 As shown.

[0020] The HCl2 form can be either hydrated or anhydrous. It exhibits moderate hygroscopicity, with a water absorption rate of approximately 2.2% at 25°C / 80% RH. This moderate hygroscopicity is considered advantageous because the water content of the crystals remains fairly constant even when humidity varies within a normal relative humidity range of approximately 30% to approximately 70% RH. It has been observed that at higher relative humidity (e.g., >85% RH), the HCl2 form absorbs moisture and transforms into the HCl3 form, believed to be a hydrate. This transformation is irreversible: the dried HCl3 form does not produce the HCl2 form, but rather a less crystalline phase of HCl3. However, the HCl2 form is believed to be stable at conditions up to 85% RH. Stability studies have shown that HCl2 is chemically stable in brine for up to 1 week and physically stable for at least 4 weeks at 25°C / 60% RH, 40°C / 75% RH, and 60°C / 38% RH.

[0021] The solubility of the two crystalline HCl salts of PN6047 has been found to be significantly higher than that of the free base. For example, while the free base is only slightly soluble in water at pH 7 (<1 mg / mL), the HCl2 and HCl3 forms are highly soluble in water at the same pH (>100 mg / mL). This higher solubility of the HCl salts allows for further studies of the compound at higher concentrations, which is advantageous, for example, in toxicological studies. Surprisingly, the bioavailability of the HCl salts of PN6047 has also been found to be significantly higher than that of the free base. Specifically, the maximum bioavailability (tested in rats) of the HCl2 form of PN6047 was 35% (oral 50 mg / kg), while the maximum bioavailability of the free base was only 8% (oral 3 mg / kg). It is anticipated that the increased bioavailability of the HCl salts (and therefore increased exposure) may lead to improved efficacy of PN6047 in the treatment of pain and other indications mentioned herein. Possibly, the increased bioavailability could allow for administration of the HCl salts at much lower doses than the free base. The unexpected increase in the bioavailability of HCl salts may also make the use of sustained-release formulations of this compound possible.

[0022] On the other hand, the present invention relates to pharmaceutical compositions comprising a therapeutically effective amount of a crystalline HCl salt of PN6047, as disclosed herein, and one or more pharmaceutically acceptable excipients. Excipients may include, for example, fillers, binders, disintegrants, flow aids, and lubricants. In some embodiments, the crystalline HCl salt of PN6047 is in the HCl2 form. In some embodiments, the crystalline HCl salt of PN6047 is in the HCl3 form.

[0023] In some embodiments, the pharmaceutical composition comprises the HCl2 or HC3 form having a polymorphic purity of at least about 90%. In some embodiments, the polymorphic purity is at least about 95%. In some embodiments, the polymorphic purity is at least about 98%. For example, the polymorphic purity is at least about 98.5%, such as at least about 99%, such as at least about 99.5%, such as at least about 99.8%, or such as at least about 99.9%. In some embodiments, the pharmaceutical composition comprises the HCl2 form and is substantially free of other crystalline HCl salts of PN6047. For example, in some embodiments, the pharmaceutical composition comprising the HCl2 form is substantially free of the HCl3 form of PN6047. In some embodiments, the HCl2 form comprises less than about 15% by weight of the HCl3 form or any other crystalline HCl salt of PN6047. For example, the HCl2 form contains less than about 14%, about 13%, about 12%, about 11%, about 10%, about 9%, about 8%, about 7%, about 6%, about 5%, about 4%, about 3%, about 2%, about 1 or less of the HCl3 form or any other crystalline HCl salt of PN6047 by weight.

[0024] In some embodiments, the pharmaceutical composition comprises the HCl3 form and is substantially free of other crystalline HCl salts of PN6047. For example, in some embodiments, the pharmaceutical composition comprising the HCl3 form is substantially free of the HCl2 form of PN6047. In some embodiments, the HCl3 form comprises less than about 15% by weight of the HCl2 form or any other crystalline HCl salt of PN6047. For example, the HCl3 form comprises less than about 14%, about 13%, about 12%, about 11%, about 10%, about 9%, about 8%, about 7%, about 6%, about 5%, about 4%, about 3%, about 2%, about 1% or less by weight of the HCl2 form or any other crystalline HCl salt of PN6047.

[0025] In some embodiments, the pharmaceutical composition comprises about 0.5% to about 99.5% by weight of a crystalline HCl salt of PN6047 as disclosed herein. For example, the composition may comprise about 0.5% to about 20%, about 20% to about 40%, about 40% to about 60%, about 60% to about 80%, or about 80% to 99.5% by weight of a crystalline HCl salt of PN6047 as disclosed herein. In some embodiments, the composition comprises about 5%, about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 77%, about 80%, about 85%, about 90%, or about 95% by weight of a crystalline HCl salt of PN6047 as disclosed herein.

[0026] In some embodiments, the pharmaceutical composition includes a filler. Examples of suitable fillers include, but are not limited to, dicalcium phosphate dihydrate, calcium sulfate, lactose (e.g., lactose monohydrate), sucrose, mannitol, sorbitol, cellulose, microcrystalline cellulose, dry starch, hydrolyzed starch, and pregelatinized starch.

[0027] In some embodiments, the pharmaceutical composition comprises a binder. Examples of suitable binders include, but are not limited to, starch, pregelatinized starch, gelatin, sugars (e.g., sucrose, glucose, dextrose, lactose, and sorbitol), polyethylene glycol, waxes, natural and synthetic gums (e.g., gum arabic and astragalus gum), sodium alginate, cellulose derivatives (e.g., hydroxypropyl methylcellulose, hydroxypropyl cellulose, and ethyl cellulose), and synthetic polymers (e.g., acrylic acid and methacrylic acid copolymers, methacrylic acid copolymers, methyl methacrylate copolymers, aminoalkyl methacrylate copolymers, polyacrylic acid / polymethacrylic acid copolymers, and polyvinylpyrrolidone (polyvinylpyrrolidone)).

[0028] In some embodiments, the pharmaceutical composition comprises a disintegrant. Examples of suitable disintegrants include, but are not limited to, dried starch, modified starch (e.g., (partially) pregelatinized starch, sodium glycolate starch, and sodium carboxymethyl starch), alginate, cellulose derivatives (e.g., sodium carboxymethyl cellulose, hydroxypropyl cellulose, and low-substituted hydroxypropyl cellulose (L-HPC)), and crosslinked polymers (e.g., carboxymethyl cellulose, crosslinked sodium carboxymethyl cellulose, calcium carboxymethyl cellulose, and crosslinked PVP (crosspovidone)).

[0029] In some embodiments, the pharmaceutical composition comprises a flow aid or lubricant. Examples of suitable flow aids and lubricants include, but are not limited to, talc, magnesium stearate, calcium stearate, sodium stearoyl fumarate, stearic acid, glyceryl betaine, colloidal anhydrous silica, hydrous silica, synthetic magnesium silicate, granular silica, starch, sodium lauryl sulfate, boric acid, magnesium oxide, waxes (e.g., carnauba wax), hydrogenated oils, polyethylene glycol, sodium benzoate, and mineral oil.

[0030] Typically, pharmaceutical compositions are prepared using conventional excipients in a conventional manner. In some embodiments, the components of the composition are mixed into a homogeneous mixture and then formulated into tablets or capsules. The homogeneous mixture of components can be compressed into tablets using conventional techniques such as a rotary tablet press. Alternatively, the mixture can be wetted by adding a liquid such as water and / or a suitable organic solvent (e.g., ethanol or isopropanol), then granulated and dried. The resulting granules can then be compressed into tablets using conventional techniques. Tablets may be coated with one or more coating layers. Coating layers may include, for example, polysaccharides (e.g., sugars or starches), cellulose-based polymers, polyvinyl polymers, acrylate copolymers, or mixtures thereof. One or more coating layers can provide regulated release of the active ingredient, such as delayed release, prolonged release, slow release, controlled release, or sustained release of the active ingredient.

[0031] Capsules (e.g., hard gelatin capsules) may contain powdered mixtures of ingredients or small multiplying particles (e.g., granules, extruded pellets, or small tablets), or liquid or semi-solid formulations of ingredients. For soft gelatin capsules, the crystalline HCl salt of PN6047 may be mixed with, for example, vegetable oils or polyethylene glycol.

[0032] Formulations intended for nasal or oral inhalation (e.g., nebulized solutions) may contain an aqueous solution of a crystalline HCl salt of PN6047 and a suitable preservative such as benzalkonium chloride. Formulations intended for topical application (e.g., ointments or creams) may contain a mixture of a crystalline HCl salt of PN6047 with, for example, an oil or wax and a suitable preservative.

[0033] On the other hand, the present invention relates to crystalline HCl salts of PN6047 disclosed herein for therapeutic purposes. The crystalline HCl salts of PN6047 disclosed herein can be used to treat or prevent pain, including but not limited to acute pain, chronic pain, neuropathic pain, cancer pain, visceral pain, diabetic pain, and pain caused by diseases or conditions such as rheumatoid arthritis, osteoarthritis, fibromyalgia, migraine, and opioid-induced hyperalgesia (OIH). They can also be used as analgesics, for example, during general anesthesia and monitoring anesthesia care.

[0034] The crystalline HCl salts of PN6047 disclosed herein can also be used to treat or prevent various mental disorders, such as depression, anxiety, and substance use disorders (including alcohol, nicotine, opioids, and other drug abuse or addiction). They can also be used to treat withdrawal and abstinence syndromes resulting from long-term use of opioids and other drugs that produce negative emotional states, including hypersensitivity to emotional and painful stimuli. Other diseases and conditions that can be treated or prevented with the crystalline HCl salts of PN6047 disclosed herein include neurodegenerative disorders (including stroke, Alzheimer's disease, Parkinson's disease), cardiovascular diseases (including ischemic heart disease), epilepsy, urinary incontinence, sensory hypersensitivity (including chronic cough and pruritus), pulmonary edema, various gastrointestinal disorders (including irritable bowel syndrome and irritable bowel disease), spinal cord injury, and sympathetic nervous system disorders (e.g., hypertension).

[0035] The crystalline HCl salts of PN6047 disclosed in this article can also be used as immunomodulators, especially for autoimmune diseases such as rheumatoid arthritis and osteoarthritis, for skin grafts and organ transplants. They can also be used for disease states with or involving opioid receptor degeneration or dysfunction.

[0036] Therefore, in one embodiment, the present invention relates to a crystalline HCl salt of PN6047 as disclosed herein, which is used to treat or prevent the diseases or conditions listed above.

[0037] In another embodiment, the present invention relates to the use of crystalline HCl salts of PN6047 as disclosed herein in the manufacture of medicaments for the treatment or prevention of the diseases or conditions listed above.

[0038] In yet another embodiment, the present invention relates to a method for treating or preventing diseases or conditions listed above in warm-blooded animals, comprising applying a therapeutically effective amount of a crystalline HCl salt of PN6047, as disclosed herein, to the warm-blooded animal in need of such treatment or prevention.

[0039] In some embodiments, the crystalline HCl salt of PN6047, as disclosed herein, may be administered in combination with at least one other therapeutic agent, such as one, two, three, or more other therapeutic agents. The crystalline HCl salt of PN6047 and at least one other therapeutic agent may be administered simultaneously, sequentially, or separately. Suitable therapeutic agents for combination with the crystalline HCl salt of PN6047 include, but are not limited to, known agents that can be used to treat any of the aforementioned conditions, disorders, and diseases.

[0040] In one embodiment, the crystalline HCl salt of PN6047, as disclosed herein, is administered in combination with one or more other analgesics. Combinations of different analgesics (with different properties) are typically used to achieve the balance of effects required to maintain an anesthetic state (e.g., amnesia, analgesia, muscle relaxation, and sedation). One or more other analgesics can be, for example, anesthetics, hypnotics, anxiolytics, neuromuscular blocking agents, neuropeptide receptor blockers, or opioids. Specific examples of such compounds include, but are not limited to, tricyclic antidepressants, gabapentin, CGRP receptor antagonists, benzodiazepines, and ketamine.

[0041] In another embodiment, the crystalline HCl salt of PN6047 disclosed herein is administered in combination with one or more other compounds that can be used to treat or prevent pain. Examples of such compounds include, but are not limited to, opioid receptor agonists and antagonists, cannabinoids, α-2-adrenergic receptor agonists, purine receptor antagonists, transient receptor potential channel blockers, sodium channel blockers, calcium channel blockers, and potassium channel blockers.

[0042] In another aspect, the present invention relates to methods for preparing PN6047 in both HCl2 and HCl3 forms. In some embodiments, the HCl2 form can be formed by direct crystallization from a suitable solvent. In some embodiments, the solvent is 2-propanol, acetone, acetonitrile, ethanol, ethyl acetate, or tetrahydrofuran. In a preferred embodiment, the solvent is 2-propanol. In some embodiments, the HCl3 form can be formed by direct crystallization from a suitable solvent or by evaporating the solvent from solution. In some embodiments, the solvent is water or acetonitrile.

[0043] In some embodiments, the method for preparing the HCl2 form of PN6047 includes the following steps:

[0044] a) Prepare a solution or suspension of the HCl salt of PN6047 in a suitable solvent;

[0045] b) Continue stirring until a solid is obtained, or until it is completely converted to the form of HCl2;

[0046] c) Recover the solids obtained in step b); and

[0047] d) Dry the solid under vacuum.

[0048] When a free base is used as a starting material, the HCl2 form of PN6047 can also be obtained. Therefore, in some embodiments, the method for preparing the HCl2 form of PN6047 includes the following steps:

[0049] a) Prepare a solution or suspension of the free base of PN6047 in a suitable solvent;

[0050] b) Add HCl solution to the solution or suspension from step a) to achieve a free base to HCl ratio of approximately 1:1;

[0051] c) Continue stirring until a solid is obtained, or until it is completely converted to the form of HCl2;

[0052] d) Recover the solids obtained in step c); and

[0053] e) Dry the solid under vacuum.

[0054] The PN6047 free base used in step a) can be crystalline or amorphous.

[0055] As used herein, the term "polymorph" refers to a crystal of the same molecules that possess different physical properties due to the order of molecules in the crystal lattice. Polymorphs of a single compound have one or more chemical, physical, mechanical, electrical, thermodynamic, and / or biological properties that differ from one another. The differences in physical properties exhibited by polymorphs can affect pharmaceutical parameters such as storage stability, compressibility, density (important in composition and product manufacturing), dissolution rate (a crucial factor determining bioavailability), solubility, melting point, chemical stability, physical stability, powder flowability, hygroscopicity, compaction, and particle morphology. Differences in stability may be due to changes in chemical reactivity (e.g., different oxidation processes causing dosage forms containing one polymorph to fade faster than those containing another) or mechanical changes (e.g., changes in crystal structure during storage as a kinetically favorable polymorph transforms into a thermodynamically more stable polymorph) or both (e.g., one polymorph is more hygroscopic than another). Due to differences in solubility / dissolution, some transformations can affect potency and / or toxicity. Furthermore, the physical properties of crystals can be important during processing; for example, a polymorph may be more prone to forming solvates, or may be more difficult to filter and wash away impurities (i.e., the particle shape and size distribution may differ between one polymorph and another). "Polymorph" does not include amorphous forms of compounds.

[0056] As used herein, the term "amorphous" refers to the non-crystalline form of a compound, which can be either the solid form or the dissolved form of the compound. For example, "amorphous" refers to a compound that does not have a regular repeating arrangement of molecules or outer surface planes.

[0057] As used herein, the term "anhydrous" or "anhydrous form" refers to the polymorph of PN6047 (i.e., crystalline HCl salt) having 1% or less, for example, 0.5% or less, 0.25% or less, or 0.1% or less water by weight.

[0058] As used herein, the term "hydrate" refers to the polymorph of PN6047 in which the crystal lattice contains water of crystallization.

[0059] The term "non-stoichiometric hydrate" refers to a polymorph of PN6047 that contains water, but variations in the water content do not cause significant changes in the crystal structure. In some embodiments, a non-stoichiometric hydrate may refer to a crystalline HCl salt of PN6047 that has channels or networks throughout its crystal structure into which water molecules can diffuse. During the drying process of a non-stoichiometric hydrate, a significant portion of the water can be removed without significantly disturbing the crystal network, and the crystal can subsequently be rehydrated to produce the initial non-stoichiometric hydrated crystalline form. Unlike stoichiometric hydrates, the dehydration and rehydration of non-stoichiometric hydrates do not involve a phase transition; therefore, all hydration states of a non-stoichiometric hydrate represent the same crystal form. In some embodiments, the non-stoichiometric hydrate may have up to about 20% water by weight, such as about 20%, about 19%, about 18%, about 17%, about 16%, about 15%, about 14%, about 13%, about 12%, about 11%, about 10%, about 9%, about 8%, about 7%, about 6%, about 5%, about 4%, about 3%, about 2%, or about 1% water by weight. In some embodiments, the non-stoichiometric hydrate may have about 1% to about 20% water by weight, such as about 1% to about 5%, about 1% to about 10%, about 1% to about 15%, about 2% to about 5%, about 2% to about 10%, about 2% to about 15%, about 2% to about 20%, about 5% to about 10%, about 5% to about 15%, about 5% to about 20%, about 10% to about 15%, about 10% to about 20%, or about 15% to about 20% water by weight.

[0060] In some embodiments, the water weight percentage of the crystalline form, such as a non-stoichiometric hydrate, is determined by Karl Fischer titration. In some embodiments, the crystalline form is dried prior to the Karl Fischer titration.

[0061] As used herein, the term "polymorph purity" when referring to compositions containing polymorphs of PN6047 refers to a percentage of one particular polymorph relative to another polymorph or amorphous form of PN6047 in a reference composition. For example, a composition containing the HCl2 form having 90% polymorph purity would contain 90 parts by weight of the HCl2 form and 10 parts by weight of other crystalline and / or amorphous forms of PN6047.

[0062] As used herein, the term "effective amount" or "therapeutic effective amount" refers to a sufficient amount of crystalline HCl salt of PN6047, which, when administered to a subject, will provide some relief from one or more symptoms of the disease or condition being treated. Results include a reduction and / or alleviation of the signs, symptoms, or cause of the disease, or any other desired alteration of the biological system. For example, an "effective amount" for therapeutic use is the amount of PN6047 required to provide a clinically significant reduction in the symptoms of a disease. The appropriate "effective" amount in any case is determined using any suitable technique, such as a dose-escalation study.

[0063] As used herein, the terms “treatment,” “treat,” and “treating” refer to reversing, reducing, delaying the onset of or inhibiting the progression of a disease or disorder or one or more symptoms thereof as described herein. In some embodiments, treatment may be administered after one or more symptoms have appeared. In other embodiments, treatment may be administered in the absence of symptoms. For example, susceptible individuals may be treated before the onset of symptoms (e.g., based on a history of symptoms and / or based on genetic or other susceptibility factors). Treatment may also continue after symptoms have resolved, for example, to prevent or delay their recurrence.

[0064] As used herein, the term “pharmaceutical acceptable” refers to compounds, materials, compositions, and / or dosage forms that are suitable for human pharmaceutical use and are generally safe, non-toxic, and have no adverse effects on biology or otherwise.

[0065] As used herein, a compound or composition is "substantially free" of one or more other components if it does not contain significant amounts of other components. Such components may include starting materials, residual solvents, or any other impurities that may arise from the preparation and / or separation of the compounds and compositions provided herein. In some embodiments, the polymorphic forms provided herein are substantially free of other polymorphic forms. In some embodiments, the specific polymorph of PN6047 (i.e., the crystalline HCl salt) is "substantially free" of other polymorphs if it constitutes at least about 95% by weight of the present PN6047. In some embodiments, the specific polymorph of PN6047 is "substantially free" of other polymorphs if it constitutes at least about 97%, about 98%, about 99%, or about 99.5% by weight of the present PN6047.

[0066] As used herein, if at least about 50% by weight of the compound is in the form of a certain polymorph, for example, if at least about 60%, at least about 70%, at least about 80%, or at least about 90% by weight of the compound is in the form of a certain polymorph, then the compound is "substantially" present in that given polymorph. In some embodiments, at least about 95%, for example, at least about 96%, for example, at least about 97%, for example, at least about 98%, for example, at least about 99%, or for example, at least about 99.5% by weight of the compound is in the form of that polymorph.

[0067] As used herein, the term "stable" means that a polymorph does not exhibit changes over time in one or more of the following: polymorphic form (e.g., an increase or decrease in some form), appearance, pH, impurity percentage, activity (as measured by in vitro assays), or osmotic pressure. In some embodiments, the polymorphs provided herein are stable for at least 1, 2, 3, or 4 weeks. For example, the polymorph does not exhibit changes in one or more of the following for at least 1, 2, 3, or 4 weeks: polymorphic form (e.g., an increase or decrease in some form), appearance, pH, impurity percentage, activity (as measured by in vitro assays), or osmotic pressure. In some embodiments, the polymorphs provided herein are stable for at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 months. For example, the polymorph does not exhibit changes in one or more of the following for at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 months: polymorphic form (e.g., an increase or decrease in some form), appearance, pH, impurity percentage, activity (as measured by in vitro assays), or osmotic pressure. In the above text, the phrase "does not show change" means that the change in any parameter measurement over the relevant time period is less than 5% (e.g., less than 4%, less than 3%, less than 2%, less than 1%).

[0068] The crystallinity of the polymorph of PN6047 can be measured, for example, by X-ray powder diffraction (XRPD) or differential scanning calorimetry (DSC). When referring to crystalline compounds herein, a crystallinity greater than about 70%, for example greater than about 80%, particularly greater than about 90%, and even more particularly greater than about 95%. In some embodiments, the crystallinity is greater than about 98%. In some embodiments, the crystallinity is greater than about 99%. % crystallinity refers to the percentage of the total sample mass that is crystallized.

[0069] As used herein, the term “about” refers to a value or parameter that includes (and describes) embodiments of that value or parameter itself. For example, a description referring to “about 20” includes a description of “20”. Numerical ranges include numbers that define the range. Generally, the term “about” refers to the indicated value of a variable and all values ​​of the variable that are within the experimental error range of the indicated value (e.g., within the 95% confidence interval of the mean) or within 10% of the indicated value, whichever is greater.

[0070] The present invention will now be described through the following embodiments, which do not limit the invention in any way. All references and citations mentioned herein are incorporated herein by reference in their entirety.

[0071] abbreviation

[0072] h hours

[0073] min minutes

[0074] TFE 2,2,2-trifluoroethanol

[0075] THF Tetrahydrofuran

[0076] rpm (revolutions per minute)

[0077] Experimental methods

[0078] The amorphous HCl salt of PN6047 was prepared by freeze-drying a mixture of the free base of PN6047 and an aqueous HCl solution. 500.5 mg of free base was dissolved in 5 mL of TFE / water at a 1:1 (v / v) ratio. 1.2 mL of 1M HCl aqueous solution was added to this solution to achieve a 1:1 free base:HCl ratio. The solution was loaded into 11 HPLC vials, frozen in liquid nitrogen, and placed under high vacuum using a freeze dryer (Alpha 2-4LD, Christ). After freeze-drying, HT-XRPD confirmed that the material was amorphous. The material was then dried at 80 °C under high vacuum (1 mbar) for 3 days to remove any residual solvent. 1 1H NMR analysis confirmed the formation of HCl after freeze-drying and the chemical integrity of PN6047.

[0079] X-ray powder diffraction (XRPD) analysis

[0080] High-throughput X-ray powder diffraction (HT-XRPD) patterns were obtained using a Crystallics T2 high-throughput XRPD system. The plates were mounted on a device equipped with corrections for intensity and geometry variations. The XRPD detector was used on a Bruker General Area Detector Diffraction System (GADDS) with a -500 gas area detector. Measurement accuracy (peak position) calibration was performed using the NIST SRM 1976 standard (Corundum). Data collection was performed at room temperature using monochromatic CuKα radiation with a 2θ region of 1.5° to 41.5°. Diffraction patterns for each aperture were collected in two 2θ ranges (first frame 1.5° ≤ 2θ ≤ 21.5°, second frame 19.5° ≤ 2θ ≤ 41.5°), with an exposure time of 45 seconds per frame. No background subtraction or curve smoothing was applied to the XRPD spectra.

[0081] Cu Kα1 radiation was used on the D8 Advance diffractometer. High-resolution X-ray powder diffraction (HR-XRPD) data were collected at room temperature using a germanium monochromator. Diffraction data were collected in the 2θ range of 1.5–41.5°2θ. Detector scans on a solid-state LynxEye detector were performed using a scan rate of 0.016° per step and 4 seconds per step. Samples were measured in an 8 mm long glass capillary with an outer diameter of 0.4 mm.

[0082] It is known in the art that X-ray powder diffraction patterns with one or more measurement errors can be obtained depending on the measurement conditions (e.g., equipment, sample preparation, or machine used). In particular, it is well known that the intensity in an XRPD pattern can fluctuate depending on the measurement conditions and sample preparation. For example, those skilled in the art of XRPD will recognize that the relative intensity of peaks can vary depending on the orientation of the sample being tested and the type and settings of the instrument used. Those skilled in the art will also recognize that the position of the reflections can be affected by the precise height of the sample within the diffractometer and the zero calibration of the diffractometer. The surface flatness of the sample can also have a small effect. Therefore, those skilled in the art will understand that the diffraction patterns presented herein should not be interpreted as absolute, and any crystalline form providing substantially the same powder diffraction patterns as those disclosed herein falls within the scope of this disclosure (for further information, see R. Jenkins and R.L.Snyder, “Introduction to X-raypowder diffractometry”, John Wiley & Sons, 1996).

[0083] Thermogravimetric analysis (TGA)

[0084] The analysis was performed on a TGA / DSC 3+STARe system (Mettler Toledo GmbH, Switzerland). The TGA / DSC 3+ was calibrated with indium and aluminum. Approximately 2 mg of sample was weighed into a 100 μL aluminum crucible and sealed. Unless otherwise specified, a pinhole was punctured in the seal, and the crucible was heated in the TGA from 25 °C to 300 °C at a heating rate of 10 °C / min. The crucible was then purged with dry N2 gas.

[0085] Differential scanning calorimetry (DSC)

[0086] Analysis was performed on a thermal flux DSC3+STARe system (Mettler-Toledo GmbH, Switzerland). The temperature and thermal function of the DSC3+ were calibrated using small indium (mp = 156.6 °C; δHf = 28.45 J / g) and zinc (mp = 156.6 °C; δHf = 28.45 J / g). Unless otherwise specified, the sample (approximately 2 mg) was sealed in a standard 40 μL aluminum dish, punctured, and heated in the DSC from 25 °C to 300 °C at a heating rate of 10 °C / min. The DSC apparatus was purged with dry N2 gas at a flow rate of 50 mL / min during the measurements.

[0087] Dynamic vapor adsorption (DVS)

[0088] Analysis was performed on a DVS-1 system from Surface Measurement Systems (London, UK). Weight balance for each step was set to dm / dt < 0.002, lasting a minimum of 1 hour and a maximum of 6 hours. Samples underwent adsorption-desorption-adsorption cycles from 40% to 95% to 0% to 45% RH at a constant temperature of 25°C. One cycle consisted of 20 steps, with each step between 0% and 90% RH performed at 10% RH. Samples were then measured using an HT-XRPD.

[0089] Example

[0090] Example 1

[0091] Preparation of HCl2 and HCl3 forms

[0092] A slurry of the amorphous HCl salt of PN6047 was prepared in pure solvent, as shown in Table 1 below. Approximately 45 mg of the amorphous salt was mixed with the solvent at room temperature. The mixture was then placed in a Crystal 16 container. TM The device and subjected to such Figure 3The temperature profiles are shown. Following the temperature profiles, the solid and liquid phases were separated by centrifugation. The solid phase was dried under ambient conditions and high vacuum (5 mbar) and analyzed by HT-XRPD before and after exposure to accelerated aging conditions (AAC; 40°C / 75% RH for 3 days). The liquid phase was also dried under high vacuum (5 mbar), and the recovered solids were analyzed by HT-XRPD.

[0093] Table 1. Experimental conditions for thermal cycling experiments

[0094]

[0095]

[0096] *Recovery from the liquid phase

[0097] The XRPD peaks of the HCl2 form are listed in Table 2 below. The HR diffraction pattern of the HCl2 form is shown below. Figure 2 As shown.

[0098] Table 2. XRPD peaks in HCl2 form

[0099]

[0100]

[0101] The XRPD peaks of the HCl3 form are listed in Table 3 below. The HT diffraction pattern of the HCl3 form is shown below. Figure 3 As shown.

[0102] Table 3. XRPD peaks in HCl3 form

[0103]

[0104]

[0105] Example 2

[0106] Differential scanning calorimetry (DSC) analysis

[0107] Due to water loss, the HCl2 form exhibits a wide range of endothermic events between approximately 25°C and approximately 100°C. Subsequently, an endothermic event is observed at approximately 228°C (starting at 222.0°C; ending at 231.5°C; peaking at 227.9°C), likely due to the melting of the anhydrous HCl salt. The DSC thermal analysis plot is shown below. Figure 4 As shown.

[0108] Due to water loss, the HCl3 form exhibits a wide range of endothermic events between approximately 70°C and approximately 150°C, which can be attributed to the dehydration of the HCl3 form. An endothermic event is then observed at approximately 167°C (starting at 159.8°C; ending at 175.2°C; peaking at 166.9°C), likely due to the melting of the anhydrous HCl salt. The DSC thermal analysis plot is shown below. Figure 5 As shown.

[0109] Example 3

[0110] Thermogravimetric analysis

[0111] The HCl2 sample exhibited a 2.5% mass loss in the temperature range of approximately 30 °C to approximately 160 °C. This mass loss is likely attributed to water removal. Thermal decomposition of the sample began at approximately 220 °C. TGA and heat flow temperature spectra are shown below. Figure 6 As shown.

[0112] The HCl3 sample exhibited a 5.1% mass loss in the temperature range of approximately 30 °C to approximately 160 °C. This mass loss is attributed to water removal. Thermal decomposition of the sample began at approximately 220 °C. TGA and heat flow temperature spectra are shown below. Figure 7 As shown.

[0113] Example 4

[0114] Dynamic vapor adsorption (DVS) analysis

[0115] DVS measurements were performed on the HCl2 and HCl3 forms to determine their hygroscopicity. The DVS isotherm plot for the HCl2 form is shown below. Figure 8 As shown, the material began to slowly absorb water as the relative humidity (RH) increased to approximately 90% RH. The mass change was approximately 3.3%, corresponding to about one water molecule per PN6047 molecule. At 25°C / 80% RH, the water absorption rate was approximately 2.2%, which (according to the hygroscopic classification of the European Pharmacopoeia) gives the material moderate hygroscopicity. From 90% to 95% RH, the mass of the material increased significantly from 3.3% to 10.0%, corresponding to approximately two additional water molecules per PN6047 molecule. The material was then gradually dried from 95% RH to 0% RH in 10% RH increments. The corresponding mass change after drying differed from the initial mass increase upon hydration. Finally, from 0% to 40% RH, the water absorption process was identical to the preceding dehydration steps. After DVS cycling, analysis of the material by HT-XRPD indicated that a conversion from the HCl2 form to the HCl3 form had occurred. It is believed that the absorption of two additional water molecules may have led to the conversion from the HCl2 form to the HCl3 form.

[0116] DVS isotherm diagram in HCl3 form as follows Figure 9As shown. The material gradually absorbed water as the relative humidity (RH) increased to 95% RH. At 25°C / 80% RH, the water absorption rate was approximately 8.0%, which (according to the hygroscopic classification of the European Pharmacopoeia) gives the material moderate hygroscopicity. The material was then gradually dried from 95% RH to 0% RH in 10% RH increments. The corresponding mass change after drying was approximately the same as the initial mass increase upon hydration. Finally, from 0% to 40% RH, the water absorption process was the same as the preceding dehydration steps. After DVS cycling, analysis of the material by HT-XRPD showed that the HCl3 form was still present.

[0117] To further understand the hygroscopicity of the HCl2 form, the material sample was incubated at 85% RH and room temperature for 2 days. XRPD analysis of the material then indicated that a conversion to the HCl3 form had occurred.

[0118] The sample in the HCl3 form was further incubated at 50 °C / 1 mbar for 2 days to determine whether conversion to the HCl2 form occurred. However, the material was recovered as a poorly crystalline phase in the HCl3 form, exhibiting additional diffraction peaks that could not be associated with any HCl form.

[0119] Example 5

[0120] Larger-scale preparation in the form of HCl2

[0121] In the scale-up experiments shown in Table 4 below, HCl2 was prepared from 2-propanol. In one experiment, 2-propanol was added to the amorphous HCl salt of PN6047. The suspension was stirred at 50°C for 1 h. In the other two experiments, crystalline free base was suspended in 2-propanol, and the suspension was stirred at 1000 rpm using a magnetic stir bar. 37% HCl solution was added to these suspensions to achieve a 1:1 free base:HCl ratio. The suspension was then stirred at an elevated temperature.

[0122] Table 4. Experimental conditions for scale-up experiments

[0123] entry Free base [mg] 37% HCl [μL] 2-Propanol [mL] condition 1 529 108 5.0 50℃,1h 2 532 108 6.5 80℃,18h 3 2162 440 21.0 50℃, 3 days

[0124] After confirming complete conversion to HCl2 by HT-XRPD, the suspension was centrifuged, and the liquid phase was removed from the solid phase using a pipette. The solid phase was dried at 50°C for 18 h, and the resulting solid was analyzed by XRPD.

[0125] Example 6

[0126] Stability study of HCl2 form

[0127] Solution stability study

[0128] The experiments were conducted in saline solution (0.9% NaCl aqueous solution). Two stock solutions in the form of HCl2 in saline solution were prepared, one at a concentration of 10 mg / mL and the other at a concentration of 100 mg / mL. The 10 mg / mL stock solution was prepared by dissolving 56 mg of material in 5 mL of saline solution. The 100 mg / mL stock solution was prepared by dissolving 196.2 mg of material in 1.75 mL of saline solution. For each experiment involving 10 mg / mL, 0.5 mL of the stock solution was transferred to an HPLC vial, while for each experiment involving 100 mg / mL, 0.15 mL of the stock solution was transferred to an HPLC vial. The HPLC vials were sealed with screw caps and placed in Crystal 16. TM They were incubated in the apparatus at different temperatures.

[0129] After the incubation period, the sample was diluted with acetonitrile / water at a 1:1 (v / v) ratio, and the API peak area was determined by LCMS. Experimental details and results are shown in Table 5.

[0130] Table 5. Experimental conditions for the stability test of solutions in salt water

[0131]

[0132]

[0133] Solid-state stability study

[0134] The solid-state stability of HCl2 was determined by incubating approximately 18 mg of sample under different conditions (temperature and relative humidity). After 1 and 4 weeks, the sample was analyzed by XRPD to determine polymorphism, by TGA to determine mass loss upon heating, and by LCMS to determine API purity. Experimental details and results are described in Table 6.

[0135] Table 6. Experimental conditions for solid-state stability test.

[0136]

[0137] Example 7

[0138] Bioavailability study

[0139] Male Wistar rats were used. Six groups of four animals each were used. Two groups received a single intravenous dose of 1 mg / kg free base or HCl2 salt, one group received a single oral dose of 3 mg / kg free base, and three groups received single oral doses of 3, 10, or 50 mg / kg HCl2 salt. Blood samples were collected 0.25, 0.5, 1, 2, 4, 6, 8, and 24 hours after intravenous administration, and 0.083, 0.25, 0.5, 1, 2, 4, 6, 8, and 24 hours after oral administration. Samples were analyzed using an LC / MS / MS system. Bioavailability (Fabs) is shown in Table 7 and calculated as follows:

[0140]

[0141] Table 7. Bioavailability

[0142] PN6047 dose Bioavailability (Fabs) Free base Oral administration 3mg / kg 8％ HCl2 salt Oral administration 3mg / kg 24％ HCl2 salt Oral administration of 10 mg / kg 35.5％ HCl2 salt Oral administration of 50 mg / kg 34.6％

Claims

1. Crystalline HC1 salt of PN6047, said crystalline HC1 salt is in the HC12 form having an XRPD pattern as shown in Figure 1 obtained with Cu Kα1 -radiation.

2. The crystalline HC1 salt according to claim 1, wherein the salt is stable at 60% relative humidity and a temperature of 25 °C.

3. The crystalline HC1 salt according to claim 1, wherein the salt is stable at 75% relative humidity and a temperature of 40 °C.

4. The crystalline HC1 salt according to any one of claims 1 to 3, wherein the salt is an anhydrate.

5. The crystalline HC1 salt according to any one of claims 1 to 3, wherein the HC12 form has a DSC curve comprising an endothermic point at 228 °C.

6. The crystalline HC1 salt according to claim 1, having a crystallinity of more than 99%.

7. A pharmaceutical composition comprising a therapeutically effective amount of the crystalline HC1 salt of PN6047 according to any one of claims 1 to 6, and one or more pharmaceutically acceptable excipients.

8. The pharmaceutical composition according to claim 7, wherein the crystalline HC1 salt of PN6047 is in the HC12 form having a polymorphic purity of at least 90%.

9. The pharmaceutical composition according to claim 8, wherein the HC12 form is free of HC13 form.

10. Use of the crystalline HC1 salt of PN6047 according to any one of claims 1 to 6 for the manufacture of a medicament for the treatment or prevention of pain.

11. The use according to claim 10, wherein the pain is acute pain, chronic pain, neuropathic pain, cancer pain, visceral pain, diabetic pain; or pain caused by rheumatoid arthritis, osteoarthritis, fibromyalgia, migraine and opioid-induced hyperalgesia.

12. A process for the preparation of the crystalline HC12 salt form of PN6047, comprising the steps of: a) preparing a solution or suspension of the HC1 salt of PN6047 in a suitable solvent; b) keeping under stirring until a solid is obtained, or until complete conversion into HC12 salt form; c) recovering the solid obtained in step b); and d) drying the solid under vacuum; said crystalline HC12 salt form of PN6047 having an XRPD pattern as shown in Figure 1 obtained with Cu Kα1 -radiation.

13. A process for the preparation of the crystalline HC12 salt form of PN6047, comprising the steps of: a) preparing a solution or suspension of the free base of PN6047 in a suitable solvent; b) adding a HC1 solution to the solution or suspension of step a) to achieve a ratio of 1 : 1 free base: HC1; c) keeping under stirring until a solid is obtained, or until complete conversion into HC12 salt form; d) recovering the solid obtained in step c); and e) drying the solid under vacuum; said crystalline HC12 salt form having an XRPD pattern as shown in Figure 1 obtained with Cu Kα1 -radiation.

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