CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Applications 63/146,217, filed February 5, 2021, and 63/211,690, filed June 17, 2021, the entire contents of which are hereby incorporated by reference.

BACKGROUND

[001] Malignant hyperthermia (MH) had a mortality rate of nearly 80 percent at the time it was identified in 1960. Treatment consisted only of cooling the patient and treating the specific symptoms, but not the underlying cause. Currently, rapid intravenous (IV) administration of dantrolene sodium (DS -IV) is the only approved mode of treatment for a MH crisis. A rapid response to MH onset is critical because death due to MH can occur as early as 30 min from onset.

FIELD OF THE TECHNOLOGY

[002] Disclosed is a co-solvent system for the formulation of a dantrolene sodium (DS) product with increased solubility for intravenous use. Further disclosed are methods for the production of a clear, concentrated pharmaceutical composition of DS product made by using a novel macromolecule co-solvent system composed of a supramolecular host molecule (such as cyclodextrin, cucurbituril etc.) and an organic solvent such as tertiary butyl alcohol (TBA). The produced DS lyophilisate dry powder may be rapidly reconstituted, producing a stable clear 2X- 20X concentrated dantrolene solution for intravenous injection, minimizing the amount of Sterile Water for Injection (WFI). The latter constitutes a significant improvement in the pharmacotherapy of patients undergoing malignant hyperthermia during surgery.

BACKGROUND

[003] The active pharmaceutical compound may comprise at least one compound selected from dantrolene and a pharmaceutically acceptable salt of dantrolene. Dantrolene is represented by the formula:

The pharmaceutically acceptable salt of dantrolene is a deprotonated form of dantrolene with a cationic counter ion. Examples of the counter ion include, but are not limited to, alkali metals, alkaline earth metals, ammonium, substituted ammonium, pyridinium, and substituted pyridinium. Examples of alkali metals include, but are not limited to, sodium and potassium. [004] The active pharmaceutical ingredient (API) dantrolene sodium (DS) is a hemiheptahydrate salt; l-5-(4-nitro phenyl)furfurylidene aminoimidazolidine-2, 4-dione, containing 14.5-17.0% (w/w) of water and has a molecular weight of 399. The anhydrous salt has a molecular weight of 336.

[005] Dantrolene sodium (USP) is an orange, odorless powder with a melting point of 279- 280°C. It is completely soluble in propylene glycol, slightly soluble in ethanol and methanol, and is insoluble in H2O (15 mg/L). Higher solubility in water at pH 8.0 or greater is exhibited by dantrolene sodium. Its free acid form (dantrolene) is totally insoluble and it is a weak acid with a pKa of about 7.5. [006] Dantrolene sodium can be used as a skeletal muscle relaxant particularly in controlling the manifestations of clinical spasticity resulting from upper neuron disorders. It is also used in the prevention and treatment of malignant hyperthermia in humans.

[007] Since 1979, dantrolene sodium has been available for the treatment of malignant hyperthermia and has contributed greatly to a dramatic decline in mortality. The syndrome must be identified and treated quickly and early for a successful outcome.

[008] Dantrolene sodium for injection comes as a dry powder that must be dissolved in sterile water prior to injection. Generally, it is supplied in small glass containers containing enough powder to give about 16 to about 20 mg of the active drug.

[009] Although most cases of malignant hyperthermia respond to 2.5-4.0 mg/kg of dantrolene initially, some patients need significantly more to bring the episode under control. In addition, recurrence of malignant hyperthermia is a possibility within the first few days of treatment.

Because of the need for continued treatment for at least 48 hours after the initial malignant hyperthermia at a dose of about 1 mg/kg every 4 hours, the Malignant Hyperthermia Association of the United States (MHAUS) recommends that 36 vials be stocked.

[0010] Dantrolene sodium (DS), the active pharmaceutical ingredient (API) undergoes slow hydrolytic decomposition in aqueous media. This degradation is accelerated at higher (alkaline) pH values and is enhanced by elevated temperatures. Thus, these conditions should be avoided as much as possible during the production of the final product (DS-IV).

[0011] The insolubility of DS in water necessitates its dissolution at a considerably higher pH than its pKa value. The higher pH of its formulation requirement results in: a) the alkaline hydrolysis (loss of potency) of DS, and b) susceptibility of its solution to carbon dioxide during its introduction into vials (filling of vials). The atmospheric carbon dioxide (CO2) through its formation of carbonic acid appears to interact with the alkaline (e.g., NaOH) content of the filled vials resulting in the reduction of the pH of their solution resulting in a possible undesirable effect in the DS formulation. Thus, the above two phenomena require that the dissolution of the DS (API) at the time of its formulation process and the subsequent introduction of its solution to vials be expedited prior to the commencement of its freeze drying.

[0012] There is a significant need in the art for a satisfactory formulation of dantrolene sodium with greater solubility in a formulation that remains stable enough for practical use.

[0013] In one aspect, disclosed are compositions and methods which may employ a novel supramolecular host molecule in combination with TBA co-solvent system to produce a highly concentrated stable and clear composition that (a) reduces freezing time of the DS-IV formulation, (b) reduces its freeze-drying time (c) shortens the reconstitution time of the DS freeze-dried product (d) formulate DS-IV at a lower pH and reduces degradation (e) significantly reduces the number of the vials needed for the MH treatment (f) provides a rapid response to MH onset (g) reduces the amount of mannitol inside each DS-IV vial, and (h) causes a considerable reduction in the fluid that is needed to be administered to the patient.

[0014] A faster reconstitution of the DS-IV product provides a great pharmacotherapeutic advantage in the treatment of patients exhibiting the life-threatening condition of malignant hyperthermia (MH) while undergoing surgery. On average, these patients generally require a rapid intravenous (IV) infusion of nine to ten (9-10) vials of DS-IV product, generally comprising from about 2.5 to about 10 mg/kg patient weight, and each reconstituted with about 60 ml of Sterile Water for Injection (WFI) (See, for example, Merck Manual, 18" Edition, 2006). In many cases, the number of DS-IV vials used ranges from about 10 to about 20 but can be even more. Cases of MH requiring as many as 36 vials of DS-IV have been recorded. The length of time to reconstitute the necessary 10-36 vials (at approximately 1 to 3 min each) creates a significant issue when considering MH death can occur in as short time as 30 min from onset. Therefore, the introduction of clear concentrated DS -IV that reduces the number of needed vials is advantageous in achieving the desired therapeutic action in MH incidents.

[0015] Organic co-solvent systems encompass a wide variety of organic solvents. Exemplary organic co- solvents include tert butyl alcohol, ethanol, n-propanol, n-butanol, iso-propanol, ethyl acetate, acetone, methyl acetate, methanol, carbon tetrachloride, dimethylsulfoxide, chlorobutanol, cyclohexane, and acetic acid.

[0016] In one aspect, the supramolecular host molecule may be selected from one or more of cyclodextrins (CDs), calixarenes (CXs) and cucurbiturils (CBn), including combinations thereof. [0017] Cyclodextrins (CDs) are cyclic oligomers of glucose, which typically contain 6, 7, or 8 glucose monomers joined by a- 1,4 linkages. Calixarenes (CXs) are macrocycle or cyclic oligomer based on a hydroxy alkylation product of a phenol and an aldehyde. Due to their superior geometric shape, calixarenes can accommodate drug molecules by forming inclusion complexes. Cucurbiturils (CBn) are macrocyclic hosts featuring n glycoluril units (5-10) linked by methylene bridges. Cucurbiturils (CB) are potential stabilizing, solubilizing, activating, and delivering agents for drugs. They may be water-soluble, for example at the concentrations disclosed herein, thermally as well as chemically stable, with a superior binding affinity. The homologues with n = 6, 7, and 8 are the mostly used in supramolecular applications. Also, the cucurbituril (CB) compound comprises at least one compound selected from CB homologues containing 5 to 10 glycoluril residues (CBn, n=5-10) joined by two methylene bridges. When guest molecules are encapsulated inside the CB cavity, the host guest complexes can inherit beneficial properties of the host molecules like enhancing solubility. The molar ratio of dantrolene sodium to the cyclodextrin and cucurbituril compound may be from about 1 : 1 to about 1:20.

[0018] The incorporation of a macromolecule into the DS product pre-lyophilized formulation results in an increase in the solubility of DS. This causes a substantial decrease in the amount of mannitol which is the usual cause of vial breakage during freeze drying. An added advantage of the increased solubility of DS, due to the host molecule like CDs, is the reduction of the added sodium hydroxide (NaOH) which results in the lesser chemical destruction of DS. The NaOH is normally added to increase the solubility of the insoluble DS. An additional beneficial effect of the host molecule is the great increase in the solubility of the lyophilized dry powder DS product, resulting in a substantial decrease in the number of administrated vials of the product and accompanying reduction in the amount of diluent liquid used for reconstitution of the vials. It takes 9 to 10 vials of the marketed DS product containing 20 milligram DS/vial to be administered to reach a concentration of 2.5 to 2.8 mg / kg at which the alleviation of the malignant hyperthermia MH symptoms occurs. In contrast only two vials of a DS product containing 120 mg/vial and only one vial of the 240 mg DS/ vial are needed to achieve a safe level of 3.4 mg/kg of DS. Added to this supramolecular host molecules beneficial contributions in the DS pre-lyophilized formulation, is the addition of TBA which induces the rapid reconstitution of the lyophilized DS dry powder for the fast treatment of MH.

[0019] The present disclosure relates generally to a macromolecule co-solvent system for formulation and production of DS with increased solubility. Also disclosed are methods of freeze-drying a DS pharmaceutical formulation. BRIEF SUMMARY

[0020] In one aspect, disclosed is a method of making a highly concentrated clear and stable dantrolene sodium (DS) formulations for intravenous use (DS-IV). This substantially almost instantaneous reconstitution of the DS-IV product constitutes a significant improvement in the pharmacotherapy of patients undergoing MH during surgery.

[0021] In one aspect, this substantially complete dissolution to a clear solution is accomplished in less than about 30 seconds. In one aspect, this substantially complete dissolution is accomplished in about 10 to about 20 seconds.

[0022] In one aspect, a method for producing the DS-IV product may comprise the following:

1. Formulation of the active pharmaceutical ingredient (API) dantrolene sodium (DS) at an alkaline pH in the range of 7.5-10.

2. Addition of a supramolecular host molecule and co-solvent to make the DS solution; and filling the vials containing the clear solution (“fill solution) to be lyophilized.

3. A lyophilization cycle of the DS clear solution to produce the freeze-dried sterile DS-IV product.

[0023] The present disclosure further relates to stable clear concentrated pharmaceutical compositions of dantrolene sodium, lyophilized dantrolene sodium and its use in treatment of various disease states, especially malignant hyperthermia and other conditions involving high fever.

[0024] In one aspect, the present disclosure relates to a pharmaceutical composition of dantrolene sodium comprising trace amounts not more than about 0.5% (w/w) of organic solvent after reconstitution of a lyophilized pharmaceutical composition of dantrolene sodium as disclosed herein.

[0025] In one aspect, the present disclosure relates to a lyophilized preparation of dantrolene sodium comprising about 0.01% to about 0.65% (w/w) dantrolene sodium after reconstitution. [0026] In one aspect, the dosage form may be about 5 to about 400 mg of dantrolene sodium, about 10 to about 30 mg of dantrolene sodium, about 10 mg to about 20 mg of dantrolene sodium, and about 20 mg of dantrolene sodium.

[0027] In one aspect, disclosed is a pharmaceutical dosage form that includes a lyophilized preparation of dantrolene sodium containing not more than about 0.05% to about 1%, or about 0.6% to about 0.7%, DS-IV (w/w). In certain aspects, dosage forms can be about 5 to about 400 mg of dantrolene sodium, about 10 to about 300 mg of dantrolene sodium, about 10 to about 100 mg of dantrolene sodium, about 20 to 400 mg of dantrolene sodium, and about 12 mg to about 22 mg of dantrolene sodium per vial or pharmaceutical container.

[0028] In one aspect, the organic solvents may include one or more of ethyl, methyl, propyl, butyl alcohol. In another aspect, the organic solvent is tertiary butanol, also known as TBA, t- butanol, tert-butyl alcohol, or tertiary butyl alcohol, alone or in combination with one or more additional solvents.

[0029] In another aspect, the dantrolene sodium product may be capable of substantial reconstitution in a carrier in less than about 60 seconds. In another aspect, the dantrolene sodium product is capable of substantial reconstitution in a carrier in about 20 seconds.

[0030] In one aspect, the lyophilized powder may be produced from the pre-lyophilization solution. Also disclosed are methods for preparing a dantrolene sodium lyophilized preparation that includes dissolving dantrolene sodium in a stabilizing concentration of an alcohol solvent of between about 1% to about 99.9% (v/v) alcohol to form a pre-lyophilization solution; and lyophilizing the pre-lyophilization solution; wherein the dantrolene sodium lyophilized preparation made from such methods may comprise mannitol and a macromolecule.

[0031] In another aspect, the concentration of organic solvent like tertiary -butanol is about 0.5% to about 30% (v/v). In another aspect, the concentration of tertiary -butanol is about 1% to about 20% (v/v). In another aspect, the concentration of tertiary -butanol is about 2% to about 10% (v/v). In one aspect, the excipients may be added before lyophilization.

[0032] In one aspect, the excipient is mannitol at a concentration of about 20 to about 100 mg/ml.

[0033] In one aspect, the pre-lyophilized concentrations of dantrolene sodium are from about 0.1 mg/ml to about 50 mg/ml.

[0034] In another aspect, lyophilizing the pre-lyophilization solution may comprise: i) cooling the pre-lyophilization solution to a temperature capable of forming a frozen solution; ii) holding the frozen solution at a temperature capable of forming a frozen solution, for a time sufficient to substantially freeze the solutions; iii) ramping the frozen solution to a primary drying temperature; iv) holding at a primary drying temperature at a temperature and for a time sufficient to form a substantially dried lyophilized product; iv) optionally ramping the dried solution to a secondary drying temperature; and v) optionally holding at the secondary drying temperature at a temperature and for a time sufficient to form a substantially dried dantrolene sodium lyophilized preparation.

In another aspect, lyophilizing the pre-lyophilization solution comprises: i) freezing the pre- lyophilization solution to a temperature below about -40 °C. for a time sufficient to substantially freeze the solution; ii) drying the frozen solution at a drying temperature between about -50 °C and about 30 °C for about 1 to about 100 hours to form a dantrolene sodium lyophilized preparation. In another aspect, lyophilizing the pre-lyophilization solution comprises: i) freezing the pre-lyophilization solution to a temperature below about -20 °C for a time sufficient to substantially freeze the solution; ii) drying the frozen solution at a drying temperature between about -60 °C and about 30 °C to form a DS lyophilized preparation. In some instances, the stable and lyophilized formulation has a freeze-drying cycle of about 72 hours or less.

[0035] In another aspect, lyophilizing the pre-lyophilization solution comprises: i) freezing the pre-lyophilization solution to a temperature below about -40 °C to form a frozen solution; ii) holding the frozen solution at or below about -40 °C for at least 2 hours; iii) ramping the frozen solution to a primary drying temperature between about -40 °C and about 30 °C to form a dried solution; iv) holding for about 10 to about 70 hours; v) ramping the dried solution to a secondary drying temperature between about 20 °C and about 40 °C; and vii) holding for about 5 to about 40 hours to form a dantrolene sodium lyophilized preparation. In another aspect, the lyophilization cycle includes starting with the pre-lyophilization solution at a shelf temperature for loading of about 0 °C to about 30 °C, about 5 °C to about 25 °C, about 5 °C to about 15 °C. [0036] In another aspect, the lyophilization cycle includes ends with unloading the lyophilized vials at about 0 °C to about 30 °C, about 5 °C to about 25 °C, about 5°C to about 15 °C.

[0037] In another aspect, the lyophilization cycle includes wherein the vacuum pressure is about 50 to about 200 microns, about 50 to about 150 microns, about 100 to about 150 microns throughout primary drying and about 50 to about 200 microns, about 50 to about 150 microns, about 100 to about 150 microns throughout secondary drying.

[0038] Also disclosed are dantrolene sodium formulations for lyophilization that may include an excipient and a stabilizing concentration of an organic solvent. In one aspect, the organic solvent may further comprise an alkali. In one aspect, the pre-lyophilization solution may comprise about 1 to about 1000 mg/ml excipient. In another aspect, the pre-lyophilization solution may comprise about 1 to about 500 mg/ml excipient. In another aspect, the pre-lyophilization solution may comprise about 10 to about 100 mg/ml excipient. One formulation includes dantrolene sodium at a concentration of about 0.01 to about 15 mg/ml, mannitol at a concentration of about 1 to about 200 mg/ml, organic solvent at a concentration of about 0.5% to about 50% (v/v) and water. Another formulation includes dantrolene sodium at a concentration of about 0.05 to about 5 mg/ml, mannitol at a concentration of about 8.0 mg/ml to about 100 mg/ml, tertiary-butyl alcohol at a concentration of about 1% to about 30% (v/v) and water.

[0039] In one aspect, a pharmaceutical dosage form of dantrolene is disclosed, wherein the dosage form may comprise a 65 ml vial or other pharmaceutically acceptable container. Concentrations of dantrolene sodium may include about 1 to about 400 mg/container, about 5 to about 50 mg/container, about 5 mg to about 20 mg/container and about 10 mg to about 20 mg/container.

[0040] In one aspect, disclosed are pre-lyophilized pharmaceutical compositions of dantrolene sodium. In one aspect the pre-lyophilized composition may include dantrolene sodium, a macromolecule, mannitol, tertiary-butyl alcohol, sodium hydroxide and water.

[0041] The above summary is not intended to describe each embodiment or every implementation of the present invention. Advantages and attainments, together with a more complete understanding of the invention, will become apparent and appreciated by referring to the following detailed description and claims taken in conjunction with the accompanying drawings. [0042] An aqueous composition may be used to produce a lyophilized dry powder which may be rapidly reconstituted into an intravenously injectable active pharmaceutical compound. The aqueous composition may comprise an active pharmaceutical compound, a macromolecule derivative, and organic solvent. The pH of the aqueous composition is greater than 7. The aqueous composition may comprise water. After the aqueous composition is formed, it is lyophilized to form the dry powder.

DETAILED DESCRIPTION

[0043] Before the present methods and compositions are described, it is to be understood that this invention is not limited to the specific methodology, devices, formulations, and compositions described as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing embodiments only and is not intended to limit the scope of the present invention, which will be limited only by the appended claims.

[0044] It must be noted that as used herein and in the appended claims, the singular forms “a”, “and”, and “the” include plural referents unless the context clearly dictates otherwise.

[0045] Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the methods, devices, and materials are now described.

[0046] To provide a clear and consistent understanding of the specification and claims, including the scope to be given such terms, the following definitions are provided:

[0047] The term “administration of the pharmaceutically active compounds and the pharmaceutical compositions” defined herein includes systemic use, as by injection (especially parenterally), intravenous infusion, suppositories, and oral administration thereof, as well as topical application of the compounds and compositions. Intravenous administration is particularly preferred in the present invention.

[0048] By “compatible” herein is meant that the components of the compositions which comprise the present invention are capable of being commingled without interacting in a manner which would substantially decrease the efficacy of the pharmaceutically active compound under ordinary use conditions.

[0049] The terms “effective amount” or “pharmaceutically effective amount” refer to a nontoxic but enough of the agent to provide a desired biological result. That result can be one or more of: reduction and/or alleviation of the signs, symptoms, or causes of a disease, such as neural diseases and malignant hyperthermia, or any other desired alteration of a biological system. Such amounts are described below. An appropriate “effective” amount in any individual case may be determined by one of ordinary skill in the art using routine experimentation.

[0050] As used herein, the term “excipient” means the substances used to formulate active pharmaceutical ingredients (API) into pharmaceutical formulations; in one aspect, an excipient does not lower or interfere with the primary therapeutic effect of the API. In one aspect, an excipient is therapeutically inert. The term “excipient’ encompasses carriers, diluents, vehicles, solubilizers, stabilizers, bulking agents, acidic or basic pH-adjusting agents and binders.

Excipients can also be those substances present in a pharmaceutical formulation as an indirect or unintended result of the manufacturing process. Excipeints are approved for or considered to be safe for human and animal administration, i.e., GRAS substances (generally regarded as safe). GRAS substances are listed by the Food and Drug Administration in the Code of Federal Regulations (CFR) at 21 CFR 182 and 21 CFR 184, incorporated herein by reference. [0051] As used herein, the terms “formulate” refers to the preparation of a drug, e.g., dantrolene, in a form suitable for administration to a mammalian patient, such as a human. Thus, “formulation’ can include the addition of pharmaceutically acceptable excipients, diluents, or carriers and pH adjusting agents.

[0052] As used herein, the term “lyophilized powder” or “lyophilized preparation” refers to any solid material obtained by lyophilization, i.e., freeze-drying of an aqueous solution. The aqueous solution may contain a non-aqueous solvent, i.e., a solution composed of aqueous and one or more non-aqueous solvent(s).

[0053] The term “organic solvent” means an organic material, usually a liquid, capable of dissolving other substances. As used herein, “trace amount of an organic solvent means an amount of solvent that is equal to or below recommended levels for pharmaceutical products, for example, as recommended by ICH guidelines (International Conferences on Harmonization, Impurities — Guidelines for Residual Sol vents. Q3C. Federal Register. 1997: 62(247):67377). The lower limit is the lowest amount that can be detected.

[0054] By “pharmaceutically acceptable” or “pharmacologically acceptable” is meant a material which is not biologically or otherwise undesirable, i.e., the material may be administered to an individual without causing any undesirable biological effects or interacting in a deleterious manner with any of the components of the composition in which it is contained.

[0055] As used herein, a “pharmaceutically acceptable carrier” is a material that is nontoxic and generally inert and does not affect the functionality of the active ingredients adversely. Examples of pharmaceutically acceptable carriers are well known, and they are sometimes referred to as diluents, vehicles, or excipients. The carriers may be organic or inorganic in nature. Examples of pharmaceutically acceptable carriers that may be present in the present lyophilized formulations may be gelatin, lactose, starch, cocoa butter, dextrose, sucrose, sorbitol, mannitol,

- 15 -olyvinylpyrrolidone (PVP) and other commonly used pharmaceutical carriers.

[0056] By “physiological pH” or a “pH” in the physiological range” is meant a pH in the range of approximately 7.2 to 8.0 inclusive, more typically in the range of approximately 7.2 to 7.6 inclusive.

[0057] The term “pharmaceutical composition” as used herein shall mean a composition that is made under conditions such that it is suitable for administration to humans, e.g., it is made under GMP conditions and contains pharmaceutically acceptable excipients, e.g., without limitation, stabilizers, pH adjusting agents such as NaOH, bulking agents, buffers, carriers, diluents, vehicles, solubilizers, and binders. As used herein pharmaceutical composition includes but is not limited to a pre-lyophilization solution or dispersion as well as a liquid form ready for injection or infusion after reconstitution of a lyophilized preparation.

[0058] A “pharmaceutical dosage form” as used herein means the pharmaceutical compositions disclosed herein being in a container and in an amount suitable for reconstitution and administration of one or more doses.

[0059] By ‘ ‘stable pharmaceutical composition” is meant any pharmaceutical composition having sufficient stability to have utility as a pharmaceutical product. The shelf-life or expiration can be that amount of time where the active ingredient degrades to a point below 90% purity. For purposes of the present invention stable pharmaceutical composition includes reference to pharmaceutical compositions with specific ranges of impurities as described herein.

[0060] As used herein, the term “subject” encompasses mammals and non-mammals. Examples of mammals include, but are not limited to, any member of the mammalia class: humans, nonhuman primates such as chimpanzees, and other apes and monkey species; farm animals such as cattle, horses, sheep, goats, swine; domestic animals such as rabbits, dogs, and cats; laboratory animals including rodents, such as rats, mice and guinea pigs, and the like.

[0061] As used herein, the terms “treating” or “treatment of a disease include preventing the disease, i.e., preventing clinical symptoms of the disease in a subject that may be exposed to, or predisposed to, the disease, but does not yet experience or display symptoms of the disease.

[0062] As used herein, the term “vial” refers to any walled container, whether rigid or flexible.

[0063] In one aspect, disclosed herein are stable, clear, pharmaceutically acceptable compositions prepared from an active pharmaceutical agent.

[0064] In one aspect, disclosed are stable pharmaceutically acceptable compositions prepared from dantrolene. In one aspect, a highly concentrated, stable, and clear formulations for the lyophilization of dantrolene sodium is disclosed. The lyophilized powder obtained from such formulations may be from about 2x to about 20x, or from about 5x to about 15x, or from about lOx to about 12x concentrated and more easily reconstituted than the presently available lyophilized powder of dantrolene.

[0065] Further disclosed are formulations of dantrolene that may be useful for treating various disease states, especially neural diseases, and malignant hyperthermia.

[0066] In another aspect, disclosed are conditions and means for enhancing the solubility of dantrolene sodium during the reconstitution process.

[0067] As described herein, a lyophilized formulation of dantrolene sodium may be achieved following removal of an organic solvent in water. Other organic solvents can be used, for example, ethanol, n-propanol, n-butanol, isoproponal, ethyl acetate, dimethyl carbonate, acetonitrile, dichloromethane, methyl ethyl ketone, methyl isobutyl ketone, acetone, 1 -pentanol, methyl acetate, methanol, carbon tetrachloride, dim ethyl sulfoxide, hexafluoroacetone, chlorobutanol, dimethyl Sulfone, acetic acid, cyclohexane. These preceding solvents may be used individually or in combination. Useful solvents must form stable solutions with dantrolene sodium and must not react chemically or appreciably degrade or deactivate the API.

[0068] The insolubility of DS in water necessitates its dissolution at a considerably higher pH than its pKa value. The higher pH of its formulation requirement results in: a) the alkaline hydrolysis (loss of potency) of DS, and b) susceptibility of its solution to carbon dioxide during its introduction into vials (filling of vials). The atmospheric carbon dioxide (CO2) appears to interact with the alkaline (e.g., NaOH) content of the filled vials resulting in the reduction of the pH of their solution resulting in a possible undesirable effect in the DS formulation. Thus, the above two phenomena require that the dissolution of the DS (API) at the time of its formulation process and the subsequent introduction of its solution to vials be expedited prior to the commencement of its freeze-drying. The DS formulation described herein has greater stability which will allow more time during the manufacturing process.

[0069] The average patient exhibiting MH requires a rapid intravenous (IV) infusion of 9-10 vials (2.5 mg/kg dose) of DS-IV product; however, rarely, as many as 36 vials of DS-IV have been required to treat a single MH episode. The currently marketed DS-IV products, which offer 20 mg/vial, require approximately one minute or less of vigorous shaking per vial to achieve enough state of reconstitution to enable administration to a patient.

[0070] Because of the time sensitive nature of a MH crisis, a clear, concentrated, and fast reconstituted vials is highly desirable, particularly if dissolution and subsequent administration to the patients is accomplished in less than thirty (30) minutes.

[0071] DANTRIUM® (dantrolene sodium) for injection comes as a dry powder that must be dissolved in sterile water prior to injection. It is currently supplied in small glass containers containing enough powder to give about 16 to about 20 mg of the active drug. RY ANODEX®

(dantrolene sodium) is an injectable suspension was approved by FDA in July 2014. However, the reconstituted solution is an orange-colored, opaque suspension and not a clear solution. While the contents of the Ryanodex vial must be used within 6 hours after reconstitution, the DS-IV described herein is stable up to 24 hours after reconstitution.

[0072] However, the described aqueous composition and lyophilized dry powder provide several improvements. The solubility of the active pharmaceutical is increased and is more stable. The dry powder can be reconstituted quickly as a clear solution. The amount of active pharmaceutical that can be solubilized from the dry powder is increased which allows fewer vials to be used for rapid treatment of MH. In addition, less of the excipient, mannitol is needed. Furthermore, the active pharmaceutical compound is more resistant to hydrolysis.

[0073] The solubility of dantrolene sodium in the selected solvent must be high enough to form commercially useful concentrations of the drug in solvent. Additionally, the solvent should be capable of being removed easily from an aqueous dispersion or solution of the drug product, e.g., through lyophilization or vacuum drying. In one aspect, a solution having a concentration of about from about 1 to about 80 mg/ml is used; in another aspect, a solution of about from about 0.05 to about 10 mg/ml is used, in another aspect, a solution of about from about 0.1 to about 3.5 mg/ml is used.

[0074] A pharmaceutically acceptable lyophilization excipient can be dissolved in the aqueous phase during the formulation process. Mannitol is one such excipient. Other excipients that may be used if desired include cyclodextrins and or cucurbiturils and pH adjusting agents. [0075] An exemplary formulation and lyophilization cycle is provided below. Lyophilization can be carried out using standard equipment as used for lyophilization or vacuum drying. The cycle may be varied depending upon the equipment and facilities used for the fill/finish.

[0076] In one aspect, an aqueous pre-lyophilization solution or dispersion may first be formulated in a pharmaceutically acceptable compounding vessel. The solution may be aseptically filtered into a sterile container, filled into an appropriately sized vial, partially stoppered and loaded into the lyophilizer.

[0077] In one aspect, using lyophilization techniques described herein, the solution may be lyophilized until moisture content in the range of from about 0.01 to about 1.0 % may be achieved. The resulting lyophilization powder can be readily reconstituted with Sterile Water for Injection, or other suitable carrier, to provide clear liquid formulations of dantrolene sodium, suitable for internal administration e.g., by parenteral injection.

[0078] A typical procedure for use in lyophilizing the pre-lyophilization solutions or dispersions is set forth below.

[0079] Initially, the product is placed in a lyophilization chamber under a range of temperatures and then subjected to temperatures well below the products freezing point, generally for several hours. In one aspect, the product is chilled below the freezing point of the solution to about -5 °C, or to about -10 °C or lower, or also to about -20 °C or lower. In one aspect, the temperature will be at or below about -40 °C for at least 2 hours. After freezing is complete, the chamber and the condenser are evacuated through vacuum pumps, the condenser surface having been previously chilled by circulating refrigerant. Typically, the condenser will have been chilled below the freezing point of the solution generally to about -40 °C. In another aspect, the condenser will have been chilled to about -45 °C or lower, in another aspect to about -60 °C or lower. Additionally, evacuation of the chamber should continue until a pressure of from about 10 to about 600 mTorr, or from about 50 to about 150 mTorr is obtained.

[0080] The product composition is then warmed under vacuum in the chamber and condenser. This usually will be carried out by warming the shelves within the lyophilizer on which the product rests during the lyophilization process at a pressure ranging from about 10 to about 600 mTorr. The warming process will optimally take place very gradually. In one aspect, the warming process will take place over the course of several hours. In one aspect, the product temperature is initially increased from about -40 °C to about 20 °C and maintained for about 10 to about 70 hours. In another aspect, the product temperature is initially increased from about -46 °C to about 20 °C and maintained for about 20 to about 40 hours.

[0081] Additionally, the product temperature can be increased to a temperature to about 25 °C to about 40 °C over a period of 0 to about 20 hours.

[0082] To prevent powder ejection of the lyophilisate from vials, complete removal of the organic solvent and water should be done during the initial drying phase. Complete drying can be confirmed by stabilization of vacuum, condenser temperature and product shelf temperature. After the initial drying, the product temperature should be increased to about 25 °C to about 40° C and maintained for about 5-40 hours.

[0083] Once the drying cycle is completed, the pressure in the chamber can be slowly released to atmospheric pressure (or slightly below) with sterile, dry-nitrogen gas (or equivalent gas). If the product composition has been lyophilized in containers such as vials, the vials can be stoppered and sealed. Several representative samples can be removed for purposes of performing various physical, chemical, and microbiological tests to analyze the quality of the product. [0084] After lyophilization, the dantrolene lyophilization powder may be filled into containers, such as 65 ml capacity vials, or alternatively the pre-lyophilization solution can be filled into such vials and lyophilized therein, resulting in vials which directly contain the lyophilized dantrolene formulation. Such vials are, after filling or lyophilization of the solution therein, sealed, as with a stopper, to provide a sealed, sterile, pharmaceutical dosage form. Typically, a vial will contain a lyophilized powder including about 10-400 mg/vial, 20-400 mg/vial, and about 100 mg/vial, dantrolene sodium and from about 5 mg to about 3.0 g/vial, and about 1 to about 3 gram per vial mannitol, or 1.5 g/vial, mannitol.

[0085] The lyophilized formulations may be reconstituted with water, such as Sterile Water for Injection, or other substantially sterile fluid such as co-solvents, to provide an appropriate solution of dantrolene sodium for intravenous administration.

[0086] The FDA approved lyophilized dantrolene sodium for intravenous injection (DS IV) product contains 20 mg of hydrated DS (API) (16.8 mg on the anhydrous basis), 3.0 grams of mannitol and enough NaOH to achieve a pH=9.5 (approximately) upon reconstitution with 60 ml of water for injection. The reconstituted product is administered as a rapid infusion to patients exhibiting the life-threatening condition of thermal hyperthermia during surgery.

[0087] In one embodiment, a stable and lyophilized formulation of dantrolene sodium made by a process comprising: a) dissolving dantrolene sodium in an alkaline solution comprising a compound selected from cyclodextrins, cucurbiturils, and an organic solvent to form a clear concentrated pre-lyophilization solution; and b) lyophilizing the clear pre-lyophilization solution to form a powder; wherein said lyophilizing comprises: starting with a shelf temperature of from about 15 to about 25 °C for loading; cooling the mixture to freezing at a temperature of from about -40 to about -50 °C for about 2 to about 4 hours to form a frozen solution; holding the frozen solution at a temperature of about -45 °C for about 2 to about 3 hours; warming the frozen solution to about -20 °C for about 2 to about 3 hours; reducing the temperature to -50 °C for about 2 to about 3 hours; increasing the temperature to about 20 °C, for about 3 to about 5 hours; holding at a temperature of about 20 °C for from about 30 to about 35 hours; ramping to a temperature of about 30 to about 40 °C for about 1 to about 2 hours; holding at a temperature of about 30 to about 40 °C for about 5 to about 7 hours: ramping to a temperature of about 25-30 °C, over about 1-2 hours; and holding at a temperature of from about 25 to about 30 °C for about 2-4 hours to form a dantrolene sodium lyophilized preparation; wherein a vacuum pressure of from about 90 to about 110 microns is maintained throughout primary drying and from about 210 to about 230 microns throughout secondary drying, to produce a final lyophilized product. This stable lyophilized formulation is added to a glass vial or other pharmaceutically acceptable container, and is reconstituted with a volume of water to provide an injectable clear solution of dantrolene sodium in a range of 20 to about 400 mg. This formulation may also comprise mannitol. The clear pre-lyophilization solution comprises dantrolene sodium at a concentration of about 0.1 to about 10 mg/ml, mannitol at a concentration of about 20 to about 100 mg/ml, organic solvent at a concentration of about 7 to about 700 mg/ml, a cyclodextrin/cucurbituril at a concentration of about 0.2 to about 300 mg/ml and an amount of sodium hydroxide adequate to adjust the pH to a range of from about 7.5 to about 10.5. The cyclodextrin compound comprises at least one compound selected from hydroxypropyl derivatives of 0- and y-cyclodextrin, a randomly methylated 0-cyclodextrin, sulfobutylether 0-cyclodextrin, and glucosyl-0- cyclodextrins. The cucurbituril (CB) compound comprises at least one compound selected from CB homologues containing 5 to 10 glycoluril residues (CBn, n=5-10) joined by two methylene bridges. The molar ratio of dantrolene sodium to the cyclodextrin and cucurbituril compound is from about 1:1 to about 1:20. The organic solvent is a water-miscible solvent, such as tertiary butanol, TBA. The vial or other pharmaceutically acceptable container contains about 20 to about 400 mg of dantrolene sodium, and the formulation is reconstituted to a clear solution in about 20 to about 60 seconds, wherein the residual concentration of an organic co-solvent is less than about 0.5% (w/w). The concentration of dantrolene sodium in the final lyophilized product is less than about 8% (w/w). The concentration of mannitol is about 1 to about 3 gram per vial or about 1.5 gram per vial. Vial capacity is approximately 65ml. The formulation is packaged in a vial or other pharmaceutically acceptable container and the formulation solution is about 96% by weight or greater dantrolene sodium and has a freeze-dry cycle of 72 hours or less. This clear injectable formulation of dantrolene sodium formed by reconstituting a lyophilized dantrolene sodium powder with a diluent is suitable for intravenous administration and is useful for the treatment of malignant hyperthermia.

[0088] EXAMPLES

[0089] Example 1

[0090] A pre-lyophilization solution is formulated in a pharmaceutically acceptable container as follow: 1) adding an excipient, such as mannitol (about 0 to about 500 mg/ml) with mixing to water at ambient temperature. 2) adding a supramolecular compound, such as cyclodextrin or cucurbituril with mixing at about 20-35 °C. 3) adding an organic solvent (0.5- 99.9% v/v), such as TBA to the aqueous solution with mixing at about 20-35 °C. 4) adding dantrolene sodium to the desired concentration with mixing. 5) adding water to achieve the final volume, and 6) cooling the solution to a temperature of from about 10 °C to about 30 °C, and about 25 °C. Quantities can be prepared on a weight basis also.

[0091] Example 2 [0092] The method for lyophilizing the pre lyophilization solution comprises:

[0093] i) cooling the pre-lyophilization solution to a temperature below about -30 °C, also below about -40 °C, to form a frozen solution.

[0094] ii) holding the frozen solution at or below -30 °C, also at or below -40 °C, at or below -50 °C, for at least 1 hour, or for at least 2 hours; also for 2-4 hours;

[0095] iii) ramping the frozen solution to a primary drying temperature between about -45 °C and about 20 °C to form a dried solution, wherein the ramping occurs over a period of at least 1 hour, or for at least 2 hours; or also for 2-3 hours;

[0096] iv) holding at a temperature of about 20 °C for about 10 to about 70 hours; or 20 to about 50 hours; or also about 30 to about 40 hours; or also from about 30 hours to about 35 hours;

[0097] v) ramping the dried solution to a secondary drying temperature between about 25 °C and about 50 °C, or at least 30 °C., or at least 35°C, or also at least 40 °C, wherein the ramping occurs over a period of at least 30 minutes, or for at least 1 hour; or also for 1-2 hours; and [0098] vi) holding at the secondary drying temperature for about 1 to about 30 hours; or 2 to about 20 hours; or also about 3 to about 10 hours; or also from about 5 hours to about 7 hours; to form a dantrolene sodium lyophilized preparation.

[0099] Example 3

[00100] A freeze-drying cycle to form the dry powder, may be produced with 5-10% (w/w) cyclodextrin, 1-10% (w/w) cucurbituril and about 1-5% (v/v) TBA aqueous co-solvent system, as follows:

1) starting with a shelf temperature of about 5 °C for loading;

2) freezing to about -50 °C, over about 4 hours;

3) holding at -50 °C for about 2-3 hours; 4) ramping to -20 °C for 2 hours;

5) ramping down to -50 °C;

6) ramping to about 20 °C, over about 3-5 hours;

7) holding at about 20 °C for 30-35 hours;

8) ramping to about 30 °C, over about 1-2 hour;

9) holding at about 30 °C for about 5-7 hours.

[00101] Upon complete the formulation and lyophilization process, the addition of cyclodextrin and or cucurbituril does not cause any undesirable loss of the strength (percent of API) of the formulation. The final reconstituted product exhibits a strength of 98+ 1%.

[00102] Example 4

[00103] The vacuum pressure is about 70 to about 130 microns throughout primary drying cycle, or the pressure is about 80 to about 120 microns throughout primary drying, or from about 90 to about 110 microns throughout primary drying. In another aspect, the vacuum pressure is about 90 to about 150 microns throughout secondary drying cycle, or the pressure is about 100 to about 140 microns throughout secondary drying, or from about 110 to about 130 microns throughout secondary drying. The vacuum pressure is about 90-110 microns throughout primary drying and 210-230 microns throughout secondary drying.

[00104] Example 5

[00105] Compared to the original freeze-drying cycle (with no TBA), the addition of TB A in the DS -IV formulation containing cyclodextrin or cucurbituril, has reduced the total freeze- drying cycle duration by 33% (i.e., from 75 hours to about 50 hours or less).

[00106] Due to the increased porous structure of the DS-IV lyophilized product which was created by the introduction of TBA, the reconstitution time of the DS-IV product with cyclodextrin or cucurbituril was decreased from 1 to 3 minutes per vial to less than 60 seconds, or 20-60 seconds. This almost instantaneous reconstitution of the DS-IV lyophilized powder constitutes a significant improvement in the treatment of patients with malignant hyperthermia. [00107] In one aspect, an aqueous composition is used to produce the lyophilized dry powder. The aqueous composition may comprise an active pharmaceutical compound, a cyclodextrin derivative or a cucurbituril derivative and a co-solvent. The active pharmaceutical compound may comprise at least one compound selected from dantrolene and a pharmaceutically acceptable salt of dantrolene. The cyclodextrin compound may comprise at least one compound selected from cyclodextrins and cyclodextrin derivatives. The co-solvent may comprise at least one compound selected from tertiary butanol, n-propanol, n-butanol, and isopropanol. The pH of the aqueous composition is greater than 7. The aqueous composition may comprise water. After the aqueous composition is formed, it is lyophilized to form the dry powder.

[00108] The concentration of the co-solvent is from about 0.5% to about 20% (v/v), such as about 2% to about 10% (v/v) and about 1% to about 5% (v/v).

[00109] In the aqueous composition, the molar ratio of the active pharmaceutical to the macromolecule compound is from about 1:1 to about 1:30. The amount can vary, such as from about 1:3 to about 1:30 and about 1:5 to about 1:18.

[00110] In the aqueous composition, the pH can vary to improve solubility. In some aspects, the aqueous composition has a pH from about 7.5 to about 10, such as from about 8.0 to about 9.5 and about 8.5 to about 9.5.

[00111] The aqueous composition is formed by mixing the active pharmaceutical with enough NaOH in sterile water to bring the pH into the range of about 9.5 to about 10.5 at about 40°-50°C for a period of about 10-20 minutes. The remaining ingredients are then added. [00112] In some aspects, the dry powder is a lyophilized (freeze-dried) powder comprising approximately 200 mg of anhydrous dantrolene sodium (API) (DS) (equivalent to 240 mg of hydrous DS containing 15.5% to 16% (w/w) of moisture), 1.5 g of mannitol, less than 3 grams of cyclodextrin or cucurbituril and enough NaOH to achieve a pH value of approximately 9.5 upon reconstitution with 60 ml of water for injection (WFI) per vial. In some preparations, the concentration of dantrolene sodium in the final lyophilized product is less than about 8% by weight.

[00113] While the present disclosure has illustrated by description several embodiments and while the illustrative embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Furthermore, features from separate lists can be combined; and features from the examples can be generalized to the whole disclosure.

[00114] The method for treating MH in a patient involves administering a therapeutically effective amount of the active pharmaceutical ingredient.