# Patent

## Title
Stable formulations for parenteral injection of small molecule drugs

## Abstract

Disclosed is a stable liquid formulation for parenteral injection comprising a biocompatible non-aqueous solvent and a small molecule drug, or a salt thereof, solubilized within the non-aqueous solvent, wherein the liquid formulation comprises less than 10% by weight residual water, and wherein the volume of the liquid formulation to be parenterally injected is from 0.1 μl to 3 ml.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application No. 61/665,021, filed Jun. 27, 2012, the contents of which are incorporated by reference.


BACKGROUND OF THE INVENTION
A. Field of the Invention
The present invention relates to pharmaceutical formulations and, more particularly, to pharmaceutical formulations of small molecule drugs having improved solubility and stability and to methods of using such pharmaceutical formulations to treat various diseases, conditions and disorders.
B. Description of Related Art
While many small molecule drugs are orally bioavailable, parenteral injection is also used in situations where the drug has insufficient oral bioavailability, the patient is unable to accept drugs orally, or there is a need for more rapid onset of drug action. For example, administration of benzodiazepines for emergency treatment of epileptic seizures, catecholemines for allergic reactions and “triptans” for the treatment of migraine headaches represent situations where oral administration is not as efficient or advisable and thus, the drugs must be administered via a non-oral route, often parenteral administration.
Standard practice for preparing formulations containing small molecule drugs has been to develop aqueous solutions for parenteral injection. A primary reason for this is that the majority of the human body is made up of water, including blood plasma, which is an aqueous environment. Therefore, there is a natural tendency to administer a drug formulation that is compatible with the environment that the drug is intended to reach. Several small molecule drugs, however, have limited solubility and poor stability in such aqueous environments. This has been solved, at least in part, by the use of co-solvents and stabilizers to more efficiently solubilize and stabilize the small molecule drug in a formulation.
An example of some of the difficulties associated with parenteral injection of small molecule drugs can be seen with diazepam. This drug, which is used for emergency treatment of epileptic seizures, has been hampered by its poor aqueous solubility. Thus, the currently available emergency treatment consists of a rectal gel. An attempt has also been made to develop a large-volume (up to 3 ml) intramuscular injection based on an aqueous formulation with co-solvents (larger volumes are needed due to lower solubility of diazepam). However, the development of this drug has been limited by the difficulty in delivering a deep, large volume intramuscular injection to a convulsing patient, as well as the pain associated with such a large dosage volume.
Further, due to the stability issues of small molecule drugs in aqueous environments, current products are oftentimes sold as lyophilized powders that require reconstitution in an aqueous carrier prior to injection. This allows for longer shelf-life of the drug active. Some products are even sold as liquids that require further dilution prior to injection with sterile water, phosphate buffer solution, or isotonic saline.
SUMMARY OF THE INVENTION
The present invention provides a solution to the current problems facing the use of small molecule drugs in therapeutic applications. In particular, the solution is premised on solubilizing and stabilizing a small molecule drug in a non-aqueous environment and then directly injecting the solubilized drug into a patient via parenteral administration. The formulation can be in liquid form. Once the formulation is prepared, it can be stored for an extended period of time (even in an injection device) and directly injected into a subject (e.g., human) without the reconstitution or dilution steps seen in current products. Indeed, this solution goes against the prevailing industry standard. In this regard, the inventors' solution has resulted in a more stable environment for the drug and a more efficient and effective way to actually provide life-saving drugs to those in need of treatment. Importantly, the inventors' discovery is widely applicable for the delivery of numerous small molecule drugs that, like diazepam, have poor or limited stability and solubility in an aqueous environment.
In one aspect of the present invention there is disclosed a stable liquid formulation for parenteral injection comprising a small molecule drug, or a salt thereof and a biocompatible non-aqueous solvent, wherein the small molecule drug is solubilized within the non-aqueous solvent. One of the unique aspects of the present invention is that it can be used for a wide variety of small molecule drugs, including those that currently being administered via parenteral injection. Some examples include benzodiazepines, catecholamines, and triptans. In one particular aspect, the compound is a benzodiazepine such as diazepam. The solubility of diazepam, by way of example, can be greater than what is typically seen with current products (e.g., the Examples show that diazepam solubility in DMSO can approach levels of 500 mM, which would allow for a wide range of dosaging options, such as for instance, reduced volumes of dosages—for instance, a diazepam formulation in DMSO can have 100 mM to 500 mM, 150 mM to 400 mM, 175 mM to 350 mM, or 200 mM to 300 mM of the drug, wherein each concentration provides for a substantially smaller volume to deliver the same quantity of drug compared to water-based preparations of diazepam. The Examples also show that the solubility of diazepam in NMP exceeded 700 mM, which allows for even smaller dosage volumes as needed). Other non-limiting small molecule drugs that can be used in the context of the present invention include epinenpherine, sumatriptan, novantrone, chemotherapy small molecules (e.g., mitoxantrone), corticosteroid small molecules (e.g., methylprednisolone), immunosuppressive small molecules (e.g., azathioprine, cladribine, cyclophosphamide, methotrexate), anti-inflammatory small molecules (e.g., salicylic acid, acetylsalicylic acid, diflunisal, choline magnesium trisalicylate, salicylate, benorylate, flufenamic acid, mefenamic acid, meclofenamic acid, triflumic acid, diclofenac, fenclofenac, alclofenac, fentiazac, ibuprofen, flurbiprofen, ketoprofen, naproxen, fenoprofen, fenbufen, suprofen, indoprofen, tiaprofenic acid, benoxaprofen, pirprofen, tolmetin, zomepirac, clopinac, indomethacin, sulindac, phenylbutazone, oxyphenbutazone, azapropazone, feprazone, piroxicam, isoxicam), small molecules used to treat neurological disorders (e.g., cimetidine, ranitidine, famotidine, nizatidine, tacrine, donepizil, metrifonate, rivastigmine, selegilene, imipramine, fluoxetine, olanzapine, sertindole, risperidone, valproate semisodium, gabapentin, carbamazepine, topiramate, phenyloin), and small molecules used to treat cancer (e.g., vincristine, vinblastin, paclitaxel, docetaxel, cisplatin, irinotecan, topotecan, gemcitabine, temozolomide, imatinib, bortezomib), statins (e.g., atorvastatin, amlodipine, rosuvastatin, sitagliptin, simvastatin, fluvastatin, pitavastatin, lovastatin, pravastatin, simvastatin), and other taxane derivatives. In particular embodiments, the small molecules that can be used include those that treat tuberculosis (e.g., rifampicin), small molecule anti-fungal agents (e.g., fluconazole), small molecule anti-anxiety agents and small molecule anti-convulsant agents (e.g. lorazepam), small molecule anti-cholinergic agents (e.g., atropine), small molecule β-agonist drugs (e.g., albuterol sulfate), small molecule mast cell stabilizers and small molecule agents used to treat allergies (e.g. cromolyn sodium), small molecule anesthetic agents and small molecule anti-arrhythmic agents (e.g., lidocaine), small molecule antibiotic agents (e.g. tobramycin, ciprofloxacin), small molecule anti-migraine agents (e.g., sumatriptan), and small molecule anti-histamine drugs (e.g., diphenhydramine). Further, the amount of the small molecule drugs in the dosage formulations can be varied depending on current acceptable amounts, subject/patient needs, and the like. With respect to the biocompatible non-aqueous solvent, examples include aprotic polar solvents, alkyl or aryl benzoate solvents, lipid solvents, protic solvents, or a mixture thereof. Non-limiting examples of aprotic solvents include dimethylsulfoxide (DMSO), dimethylformamide (DMF), ethyl acetate, n-methylpyrrolidone (NMP), dimethyl acetamide (DMA), propylene carbonate, or mixtures thereof. In some instances, however, the formulations of the present invention do not have to include the aforementioned solvents (i.e., others can be used). In one instance, for example, the formulations do not include non-aqueous aprotic polar solvents and/or do not include non-aqueous protic solvents (e.g., polyethylene glycol (PEG), propylene glycol (PG), polyvinylpyrrolidone (PVP), methoxypropylene glycol (MPEG), glycerol, glycofurol, and mixtures thereof). As noted above, the increased solubility of the small molecule drugs can result in small dosage volumes (and, in turn, small storage devices and containers), which provides for an easier and less painful administration parenterally. Non-limiting examples of aryl or alkyl benzoate solvents include methyl benzoate, ethyl benzoate, propyl benzoate, C12-C15 alkyl benzoates, in which R is a C12-15 alkyl group, C16-17 alkyl benzoate, in which R is a C16-17 fatty alcohol group, and benzyl benzoate. A non-limiting example of a lipid is triacetin, which is the triester of glycerol and acetic acid. Non-limiting examples of protic solvents include polyethylene glycol (PEG), propylene glycol (PG), polyvinylpyrrolidone (PVP), methoxypropylene glycol (MPEG), glycerol, glycofurol, or mixtures thereof. In certain aspects, the formulation does not include a co-solvent, while in other aspects it can include a co-solvent. In one instance, the formulation can include a single/only one biocompatible non-aqueous solvent (i.e., in neat or pure form). In other aspects, the formulation includes a mixture of two, three, four, or more biocompatible non-aqueous solvents. In still additional aspects, the formulation can exclude co-solvents, salts, and other ingredients that can help with or increase the solubility of the small molecule drug in the non-aqueous solvent. For instance, the formulation can consist of or consist essentially of a small molecule drug and a non-aqueous solvent (or mixture of non-aqueous solvents) and still be directly injected through parenteral administration to a subject (with consist essentially of meaning in the context of this sentence exclusion of other ingredients that could increase the solubility of the drug within the non-aqueous solvent (or mixture of non-aqueous solvents—e.g., a preservative can be included to further preserve the injectible formulation). Further, the formulation of the present invention can be non-aqueous or substantially non-aqueous (e.g., less than 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5% or less of water by weight or volume). In some instances, the small molecule drug has previously been dried in the presence of a buffer prior to being solubilized in the non-aqueous solvent. As explained below, this can add to the stability of the small molecule drug. In some instances, the dried small molecule drug has a pH memory that is about equal to the pH of the small molecule drug in the presence of the aqueous buffer such that the pH of the small molecule drug that is solubilized in the biocompatible non-aqueous solvent is about equal to the pH of the small molecule drug in the presence of the buffer. The memory pH can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or more or can be a range of 1 to 3, 2 to 4, 3 to 5, 4 to 6, 5 to 7, 6 to 8, 7 to 9, 8 to 10 or 9 to 11. In certain aspects, the buffer is a non-volatile buffer (non-limiting examples of which include glycine buffers, citrate buffers, or phosphate buffers, or a mixture thereof). In other instances, the buffer can be a volatile buffer. Further, the water content of the small molecule drug can be less than 5%, 4%, 3%, 2%, 1%, 0.5% or less w/w. In certain aspects, the formulation includes from 0.5 mg/mL to about 300 mg/mL, 10 mg/mL to 50 mg/mL, 20 mg/mL to 50 mg/mL, 5 mg/mL to 15 mg/mL, or 0.5 mg/mL to 2 mg/mL of the small molecule drug. In some instances, the amount of the small molecule drug can be as high as 400, 500, 600, 700, 800, 900, 1000, 2000, or 3000 mg/mL or more. One of the unique aspects of the present formulation is that the formulation can have a high content of the drug, yet the dosage amount of the formulation can be relatively low (e.g., 0.1 μl, 1 μl, 10 μl, 20 μl, 50 μl, 75 μl, 100 μl, 200 μl, 300 μl, 400 μl, 500 μl, 600 μl, 700 μl, 800 μl, 900 μl, 1 ml, 2 ml, or 3 ml, or more as needed (e.g., 4, 5, 6, 7, 8, 9, 10 ml or more). In certain instances, the volume of the liquid formulation to be parenterally injected is 3 ml or less (e.g., 3, 2.5, 2, 1.5, 1, 0.5, 0.1 ml or less) or is from 0.1 μl to 3 ml or from 0.1 μl to 1 μl or from 1 μl to 10 μl or from 10 μl to 1 ml or from 0.1 μl to 2.5 ml or from 0.1 μl to 2 ml or from 0.1 μl to 1.5 ml or from 0.1 μl to 1 ml or from 0.1 μl to 0.5 ml or from 0.1 μl to 0.1 ml. Another unique aspect of the present formulation is that it can be contained in a container or device, be stored, and be immediately ready for parenteral injection on an as needed basis without having to reconstitute or dilute the formulation. The device can be a syringe, a pen injection device, an auto-injector device, a device that can pump or administer the formulation (e.g., automatic or non-automatic external pumps, implantable pumps, etc.) or a perfusion bag. Also contemplated for use in the formulations are additional ingredients/pharmaceutical excipients, non-limiting example of which include: antioxidants (examples include ascorbic acid, cysteine, methionine, monothioglycerol, sodium thiosulfate, sulfites, BHT, BHA, ascorbyl palmitate, propyl gallate, or vitamin E); chelating agents (examples include EDTA, EGTA, tartaric acid, glycerin, or citric acid); or preservatives (examples include alkyl alcohols, benzyl alcohol, a methyl paraben, or a propyl paraben or mixtures thereof). The formulation can be in liquid form, semi-solid form, or gel form. As discussed below, the formulation can have a desired viscosity range (in one non-limiting example, such a range could be between 0.5 to 15 cps). The formulation can be such that at least 65% of the small molecule drug within the formulation remains chemically and physically stable when the formulation is stored at room temperature for two months or at least 80% of the therapeutic agent within the formulation remains chemically and physically stable when the formulation is stored at room temperature for two months.
In one particular aspect of the present invention, there is disclosed a stable liquid formulation for parenteral injection comprising diazepam, or a salt thereof that has a water content of less than 1% w/w and a biocompatible non-aqueous solvent, wherein the diazepam is solubilized within the non-aqueous solvent, wherein the water content of the formulation is less than 5% w/v, wherein the volume of the formulation to be parenterally injected is between 50 μl to 1000 μl or any range therein (e.g., 75 μl, 100 μl, 150 μl, 200 μl, 300 μl, 400 μl, 500 μl, 600 μl, 700 μl, 800 μl, 900 μl, etc.). As explained above, such a formulation can be comprised in a container selected from the group con a sealed syringe, a sealed pen injection device, a sealed auto-injector device, or a pump. Also as explained above, the diazepam can be been dried in the presence of a buffer prior to being solubilized in the non-aqueous solvent. This can provide the dried diazepam with a pH memory that is about equal to the pH of diazepam in the presence of the aqueous buffer such that the pH of the diazepam that is solubilized in the biocompatible non-aqueous solvent is about equal to the pH of the diazepam in the presence of the aqueous buffer (e.g., the aforementioned non-volatile buffers such as glycine buffers, citrate buffers, or phosphate buffers, or a mixture thereof).
Also disclosed is a method of administering the formulations of the present invention by parenteral administration of the formulation to a subject in need thereof. The administration can be performed without having to reconstitute and/or dilute the formulation. Further, the administration can be performed with a syringe, a pen injection device, an auto-injector device, a pump, or a perfusion bag. Also, the formulation can be stored in said syringe, pen injection device, auto-injector device, pump, or perfusion bag, which can then be immediately used (again without having to reconstitute and/or dilute the formulation). Further, and as noted above, the amount of the formulation being administered can range from 1 μl, 10 μl, 20 μl, 50 μl, 75 μl, 100 μl, 200 μl, 300 μl, 400 μl, 500 μl, 600 μl, 700 μl, 800 μl, 900 μl, 1 ml, 2 ml, 3 ml, 4 ml, 5 ml, 6 ml, 7 ml, 8 ml, 9 ml, or 10 ml, or more as needed. In certain aspects, the formulations are such that the small molecule drug remains stable and solubilized (i.e., no coalescence or crystallization of the small molecule drug) and when stored at room temperature (approximately 20-25° C.) for at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 months.
In a further aspect of the present invention there is disclosed a method for treating or preventing a condition, disease, disorder, etc. comprising administering to a subject in need thereof any one of the formulations of the present invention in an amount effective to treat or prevent the condition, disease, disorder, etc. For instance, and with respect to the aforementioned diazepam formulation, such formulations can be used to treat epileptic seizure, especially severe seizures in an emergency situation. In this instance, the method can include administering to the subject in need thereof a soluble and stable diazepam formulation of the present invention in an amount effective to treat the seizure. The aforementioned administration techniques can be used (e.g., parenterally, pre-loaded containers, etc.). In some aspects, the condition can be anxiety, muscle spasms, or seizures (e.g., epileptic seizure).
Also contemplated is a method of the stable formulations of the present invention. The method can include obtaining a small molecule drug and adding one or more biocompatible non-aqueous solvents in an amount to sufficient dissolve the small molecule drug in the solvent. The method can further include storing the formulation in a container such as a vial or in a syringe, a pen injection device, an auto-injector device, a pump, or a perfusion bag. The process can further include drying the small molecule drug in the presence of a buffer prior to adding in the non-aqueous solvent(s). In a broader aspect, the process can be applied to formulate any small molecule drug that has limited or poor solubility or stability in an aqueous environment.
As briefly mentioned above, it is also contemplated that the viscosity of the formulations can be selected to achieve a desired result, e.g., depending on the type of composition desired, the route of administration, and the like. In one instance, the viscosity of the formulations can be from about 0.5 cps to well over 1 million cps or any range or integer derivable therein (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 20000, 30000, 40000, 50000, 60000, 70000, 80000, 90000, 100000, 200000, 300000, 400000, 500000, 600000, 700000, 800000, 900000, 1000000 cps, etc., as measured on a Brookfield Viscometer using a TC spindle at 2.5 rpm at 25° C.). In particular aspects, however, a viscosity range between 0.5 cps to about 100 cps or about 0.5 cps to about 15 cps can be used.
It is contemplated that any embodiment discussed in this specification can be implemented with respect to any method or composition of the invention, and vice versa. Furthermore, compositions of the invention can be used to achieve methods of the invention.
“Aprotic polar solvent” means a polar solvent that does not contain acidic hydrogen and does not act as a hydrogen bond donor. Examples of polar aprotic solvents include dimethylsulfoxide (DMSO), dimethylformamide (DMF), ethyl acetate, n-methylpyrrolidone (NMP), dimethylacetamide (DMA) and propylene carbonate.
“Alkyl or aryl benzoates” refers to the following compound:




where R is an alkyl or aryl group. Examples of alkyl benzoates include methyl benzoate, ethyl benzoate, propyl benzoate, C12-C15 alkyl benzoates, in which R is a C12-15 alkyl group, and C16-17 alkyl benzoate, in which R is a C16-17 fatty alcohol group. A non-limiting example of aryl benzoate includes benzyl benzoate.

“Parenteral injection” refers to the administration of small molecule drugs via injection under or through one or more layers of skin or mucus membranes of an animal, such as a human. Standard parenteral injections are given into the subcutaneous, intramuscular, or intradermal region of an animal, e.g., a human patient. These deep locations are targeted because the tissue expands more easily, relative to shallow dermal sites, to accommodate the 0.1-3.0 cc (mL) injection volumes required to deliver most therapeutic agents.
“Pharmaceutically acceptable carrier” means a pharmaceutically acceptable solvent, suspending agent or vehicle for delivering a drug compound of the present invention to a mammal such as an animal or human.
“Pharmaceutically acceptable” ingredient, excipient or component is one that is suitable for use with humans and/or animals without undue adverse side effects (such as toxicity, irritation and allergic response) commensurate with a reasonable benefit/risk ratio.
“Chemical stability” means that with respect to the small molecule drug, an acceptable percentage of degradation products produced by chemical pathways such as oxidation or hydrolysis is formed. In particular, a formulation is considered chemically stable if no more than about 20% breakdown products are formed after one year of storage at the intended storage temperature of the product (e.g., room temperature); or storage of the product at 30° C./60% relative humidity for one year; or storage of the product at 40° C./75% relative humidity for one month, and preferably three months, and more preferably six months.
“Physical stability” means that with respect to the small molecule drug, an acceptable percentage of crystals or other aggregates (e.g., dimers, trimers, etc.) is formed. In particular, a formulation is considered physically stable if no more that about 15% aggregates are formed after one year of storage at the intended storage temperature of the product (e.g., room temperature); or storage of the product at 30° C./60% relative humidity for one year; or storage of the product at 40° C./75% relative humidity for one month, and preferably three months, and more preferably six months.
“Stable formulation” means that at least about 65% chemically and physically stable small molecule drug remains after two months of storage at room temperature. In some aspects, the formulations retain at least about 80% chemically and physically stable small molecule drug under these conditions. Even further, some stable formulations are those which do not exhibit degradation after sterilizing irradiation (e.g., gamma, beta or electron beam).
“Bioavailability” refers to the extent to which the small molecule drug is absorbed from the formulation by the subject.
“Systemic” means, with respect to delivery or administration of a small molecule drug to a subject, that therapeutic agent is detectable at a biologically significant level in the blood plasma of the subject.
“Controlled-release” refers to the release of the small molecule drug at such a rate that blood (e.g., plasma) concentrations are maintained within the therapeutic range, but below toxic concentrations over a period of time of about one hour or longer, preferably 12 hours or longer.
“Patient,” “subject,” or “individual” refers to a mammal (e.g., human, primate, dog, cat, bovine, ovine, porcine, equine, mouse, rate, hamster, rabbit, or guinea pig).
“Inhibiting” or “reducing” or any variation of these terms, when used in the claims and/or the specification includes any measurable decrease or complete inhibition to achieve a desired result.
“Effective” or “treating” or “preventing” or any variation of these terms, when used in the claims and/or specification, means adequate to accomplish a desired, expected, or intended result.
The term “about” or “approximately” are defined as being close to as understood by one of ordinary skill in the art, and in one non-limiting embodiment the terms are defined to be within 10%, preferably within 5%, more preferably within 1%, and most preferably within 0.5%. Further, “substantially non-aqueous” refers to less than 5%, 4%, 3%, 2%, 1%, or less by weight or volume of water.
The use of the word “a” or “an” when used in conjunction with the term “comprising” in the claims and/or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.”
The words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.
The compositions and methods for their use can “comprise,” “consist essentially of,” or “consist of” any of the ingredients or steps disclosed throughout the specification. With respect to the transitional phase “consisting essentially of,” in one non-limiting aspect, a basic and novel characteristic of the formulations and methods disclosed in this specification includes the stability and solubility of the small molecule drugs within said formulations. Therefore, ingredients that can negatively or positively affect the stability or solubility of the small molecule drugs within the formulations would be excluded from said formulations in instances where a claim uses the transitional phrase “consisting essentially of.”
Other objects, features and advantages of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and the examples, while indicating specific embodiments of the invention, are given by way of illustration only. Additionally, it is contemplated that changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1: Plasma diazepam levels in rats after administration of 1 mg diazepam as subcutaneous injections of XeriSolTM diazepam in the indicated solvents or as Diastat rectal gel. Curves represent 5 animals per group except as otherwise noted.



DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
As discussed above, the difficulties associated with formulating small molecule drugs for parenteral administration are well-documented. The current solutions to such difficulties are also well-documented and accepted as standard practice in the formulations field. Briefly, the problems begin with the desire to create aqueous formulations for small molecule drugs that would be well-tolerated and dispersible within the body (and in particular, the blood stream) despite the fact that most small molecule drugs have low solubility and stability in aqueous environments. This typically results in the use of co-solvents and drug stability agents, which can result in large and/or multiple dosages (e.g., upwards of 3 mL) to ensure that a sufficient amount of the drug is administered. Further, the added steps of reconstitution and/or dilution prior to injection can be costly and time consuming.
To address the current issues associated with parenteral administration of small molecule drugs, the inventors offer a unique approach that goes against the well-accepted and traditional formulation standards. In particular, the inventors have discovered that by solubilizing a small molecule drug in a non-aqueous environment, the resulting formulation is not only highly concentrated with the drug (which then leads to a lower dosage volume of the formulation), it also provides for increased stability and solubility of said drug. This in-turn leads to a more stable formulation that enjoys a longer shelf/storage life that can be directly injected into a subject without the use of a reconstitution or dilution step. Thus, the formulations of the present invention can be stored in a device that can immediately be used for parenteral administration.
These and other non-limiting aspects of the present invention are discussed below.
A. Small Molecule Drugs
“Small molecule drugs” in the context of the present invention are biologically active compounds (and salts thereof) that can bring about a desired, beneficial, and/or pharmacological effect on a subject. These “small molecule drugs” are organic or inorganic compounds, but they are not polymers (e.g., peptides, proteins, polypeptides, carbohydrates, and nucleic acids). Therefore, the small molecule drugs in the context of the present invention are not polymeric compounds. Typically, the small molecule drugs have a molecular weight of less than approximately 1000 Daltons. Certain small molecule drugs are “moisture sensitive” in that they are increasingly unstable in the presence of water. Also, salts that can be used with the small molecule drugs are known to those skilled in the art and include salts with inorganic acids, organic acids, inorganic bases, or organic bases.
Non-limiting examples of a few classes of small molecule drugs that can be used in the context of the present invention include benzodiazepines, catecholemines, and “triptans.” As noted in the examples, one such drug diazepam, has been shown to work well in the context of the present invention as evidenced by its increased stability and solubility in a non-aqueous solvent. Other non-limiting examples include epinenpherine, sumatriptan, novantrone, chemotherapy small molecules (e.g., mitoxantrone), corticosteroid small molecules (e.g., methylprednisolone, beclomethasone dipropionate), immunosuppressive small molecules (e.g., azathioprine, cladribine, cyclophosphamide monohydrate, methotrexate), anti-inflammatory small molecules (e.g., salicylic acid, acetylsalicylic acid, diflunisal, choline magnesium trisalicylate, salicylate, benorylate, flufenamic acid, mefenamic acid, meclofenamic acid, triflumic acid, diclofenac, fenclofenac, alclofenac, fentiazac, ibuprofen, flurbiprofen, ketoprofen, naproxen, fenoprofen, fenbufen, suprofen, indoprofen, tiaprofenic acid, benoxaprofen, pirprofen, tolmetin, zomepirac, clopinac, indomethacin, sulindac, phenylbutazone, oxyphenbutazone, azapropazone, feprazone, piroxicam, isoxicam), small molecules used to treat neurological disorders (e.g., cimetidine, ranitidine, famotidine, nizatidine, tacrine, donepizil, metrifonate, rivastigmine, selegilene, imipramine, fluoxetine, olanzapine, sertindole, risperidone, valproate semisodium, gabapentin, carbamazepine, topiramate, phenyloin), small molecules used to treat cancer (e.g., vincristine, vinblastin, paclitaxel, docetaxel, cisplatin, irinotecan, topotecan, gemcitabine, temozolomide, imatinib, bortezomib), statins (e.g., atorvastatin, amlodipine, rosuvastatin, sitagliptin, simvastatin, fluvastatin, pitavastatin, lovastatin, pravastatin, simvastatin), and other taxane derivatives, small molecules used to treat tuberculosis (e.g., rifampicin), small molecule anti-fungal agents (e.g., fluconazole), small molecule anti-anxiety agents and small molecule anti-convulsant agents (e.g., lorazepam), small molecule anti-cholinergic agents (e.g., atropine), small molecule f3-agonist drugs (e.g., albuterol sulfate), small molecule mast cell stabilizers and small molecule agents used to treat allergies (e.g., cromolyn sodium), small molecule anesthetic agents and small molecule anti-arrhythmic agents (e.g., lidocaine), small molecule antibiotic agents (e.g., tobramycin, ciprofloxacin), small molecule anti-migraine agents (e.g., sumatriptan), and small molecule anti-histamine drugs (e.g., diphenhydramine).
Each of the aforementioned drugs are well-known and commercially available from a wide variety of sources. Further, the amount of the small molecule drugs in the dosage formulations can be varied depending on current acceptable amounts, subject/patient needs (e.g., age, health, weight, nature and extend of symptom), and the like. What is unique in the context of the present invention is the fact that the dosage volumes can be decreased, and concentrated liquid preparations of the compounds can be pre-made and stored, given the increased solubility and stability of the small molecule drugs within the formulations of the present invention.
B. Biocompatible Non-Aqueous Solvents
“Biocompatible non-aqueous solvent” in the context of the present invention refers to a solvent that is substantially to completely devoid of water and is capable of solubilizing a small molecule drug. The solvent is also biocompatible in that it is suitable for use with human or animals without undue adverse side effects (such as toxicity, irritation, and allergic response) commensurate with a reasonable benefit/risk ratio.
Non-limiting examples of some suitable biocompatible, non-aqueous solvents include aprotic polar solvents, alkyl or aryl benzoates, and lipids. Examples of polar aprotic solvents include dimethylsulfoxide (DMSO), dimethylformamide (DMF), ethyl acetate, n-methyl pyrrolidone (NMP), dimethylacetamide (DMA), propylene carbonate, and mixtures thereof. Non-limiting examples of alkyl benzoates include methyl benzoate, ethyl benzoate, propyl benzoate, C12-C15 alkyl benzoates, in which R is a C12-15 alkyl group, and C16-17 alkyl benzoate, in which R is a C16-17 fatty alcohol group. A non-limiting example of aryl benzoate includes benzyl benzoate. A non-limiting example of a lipid is triacetin, which is the triester of glycerol and acetic acid.
Each of the aforementioned non-aqueous solvents are well-known and commercially available from a wide variety of sources.
C. pH Memory
In addition to the non-aqueous solvent aspect of the present invention, the inventors also discovered a further processing step that can be used to further stabilize the small molecule drug within the formulation. In particular, a small molecule drug can be mixed with a non-volatile buffer, and then dried to obtain a small molecule drug powder. Drugs are susceptible to hydrolysis at certain bonds, so the use of non-volatile buffers in the formulations of the present invention are believed to beneficially affect their chemical stability. The result of this process step is the production of a “pH memory” of the small molecule drug after it is reconstituted in then non-aqueous solvent.
In particular, the “pH memory” of small molecule drug is the resulting charge profile (protonation state) after drying the drug from a buffered aqueous solution (e.g., from a non-volatile buffer). The protonation state, and thus the solubility and stability of the drug, in very low or zero moisture non-aqueous solvents are affected by the aqueous pH of the drug solution before drying and the drying conditions employed. Similarly, the stability of uncharged drugs is impacted by pH in aqueous solutions, and thus, pH memory in a dried state or in a non-aqueous solvent. When the drug is dried in a buffer species in which both the acidic and basic components are non-volatile, the pH memory of the dried drug will be about equal to the pH of the drug in the non-volatile buffer. See, e.g., Enzymatic Reactions in Organic Media, Koskinen, A. M. P., and Klibanov, A. M., eds., Springer (1996). Furthermore, the pH of the buffered aqueous solution (e.g., non-volatile buffer) in which the drug is dried can be optimized to yield a pH memory for the drug that results in optimal drug stability, maximum solubility, and minimal degradation when the dried drug is subsequently reconstituted in the non-aqueous solvent (e.g., aprotic polar solvent). It should be noted that many non-aqueous solvents do not have exchangeable protons. Therefore, when a dried drug is reconstituted into such a solvent, the drug in the reconstituted formulation will maintain the solubility and stability characteristics of the optimal pH memory. In particular embodiments, the drug in the formulation will have a pH memory of about 2.0 to 3.0 to ensure maximal stability/minimal degradation. In other embodiments, the drug in the formulation will have a pH memory of about 3.0 to 5.0 to ensure maximal stability/minimal degradation. In yet other embodiments, the drug will have a pH memory of about 4.0 to 6.0 to ensure maximal stability/minimal degradation. In yet other embodiments, the drug will have a pH memory of about 6.0 to 11.0 to ensure maximal stability/minimal degradation.
The pH memory of a drug can be measured in several ways. In one method, the pH memory of a drug is measured by reconstituting the dried drug into un-buffered water and measuring the pH of the reconstituted drug with a pH indicator such as pH paper or a calibrated pH electrode. Alternatively, the pH memory of a drug can be determined for a drug that has been reconstituted in a non-aqueous solvent by adding at least 20% water to the non-aqueous solvent and measuring the pH with a pH indicator. See, e.g., Baughman and Kreevoy, “Determination of Acidity in 80% Dimethyl Sulfoxide-20% Water,” Journal a/Physical Chemistry, 78(4):421-23 (1974). Measurement of pH in an aprotic polar solvent-water solution may require a small correction (i.e., no more than 0.2 pH unit as per Baughman and Kreevoy, supra).
In view of the above, non-volatile buffers that are useful in the formulations described herein are those that are helpful in establishing a pH of maximum stability/minimal degradation as well as those that are helpful in removing residual water content from the dried drug powder. Nonvolatile buffers include those buffers that will not evaporate away in a manner similar to water upon drying/lyophilization. Suitable nonvolatile buffers include, for example, glycine buffers, citrate buffers and phosphate buffers. In one preferred embodiment, the nonvolatile buffer is a glycine buffer or a citrate buffer.
In the foregoing process, drying of the drug compound with the nonvolatile buffer can be carried out using spray-drying techniques, freeze-drying techniques or lyophilization techniques. Spray drying techniques are well known to those skilled in the art. Spray drying includes the steps of atomization of a solution containing one or more solids (e.g., therapeutic agent) via a nozzle spinning disk, or other device, followed by evaporation of the solvent from the droplets. The nature of the powder that results is the function of several variables including the initial solute concentration, size distribution of droplets produced and the rate of solute removal. The particles produced may comprise aggregates of primary particles which consist of crystals and/or amorphous solids depending on the rate and conditions of solvent removal.
A spray-drying process for preparing ultra-fine powders of drugs is described, for example, in U.S. Pat. No. 6,051,256. Freeze-drying procedures are well known in the art, and are described, for example, in U.S. Pat. Nos. 4,608,764 and 4,848,094. Spray-freeze-drying processes are described, for example, in U.S. Pat. No. 5,208,998. Other spray-drying techniques are described, in U.S. Pat. Nos. 6,253,463; 6,001,336; 5,260,306; and PCT International Publication Nos. WO91/16882 and WO 96/09814.
Lyophilization techniques are well known to those skilled in the art. Basically, lyophilization is a dehydration technique that takes place while a product is in a frozen state and under a vacuum (ice sublimation under a vacuum) and drying by gentle heating. These conditions stabilize the product, and minimize oxidation and other degradative processes. The conditions of freeze drying permit running the process at low temperatures, therefore, thermally labile products can be preserved. Steps in freeze drying include pretreatment, freezing, primary drying and secondary drying. Pretreatment includes any method of treating the product prior to freezing. This may include concentrating the product, formulation revision (i.e., addition of components to increase stability and/or improve processing), decreasing a high vapor pressure solvent or increasing the surface area. Methods of pretreatment include: freeze concentration, solution phase concentration, and formulating specifically to preserve product appearance or to provide lyoprotection for reactive products, and are described, e.g., in U.S. Pat. No. 6,199,297. “Standard” lyophilization conditions, are described, e.g., in U.S. Pat. No. 5,031,336, and in “Freeze Drying of Pharmaceuticals” (DeLuca, Patrick P., J. Vac. Sci. Technol., Vol. 14, No. 1, January/February 1977); and “The Lyophilization of Pharmaceuticals: A Literature Review” (Williams, N. A., and G. P. Polli, Journal of Parenteral Science and Technology, Vol. 38, No. 2, March/April 1984).
In certain aspects, the lyophilization cycle can be partially performed above the glass transition temperature (Tg) of the therapeutic agent formulation to induce a collapse of the mass to form a dense cake containing residual water. In other embodiments, the lyophilization cycle is carried out below the glass transition temperature in order to avoid a collapse in order to achieve a complete drying of the particles.
D. Moisture Content of Formulations
An additional key aspect of the formulations of the present invention is that they have a low moisture content by virtue of using the previously described non-aqueous solvents. This provides for additional stability of both the formulation and the small molecule drug. For instance, the stable formulations of the present invention can have a moisture content that is less than 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.25%, 0.1%, 0.05%, 0.025%, 0.01%, to 0% by weight or volume of the formulation. In some instances, the formulation includes from about 0.01% to about 3%, from about 0.01% to about 2%, from about 0.01% to about 1.5% or from about 0.01% to about 1% by weight or volume of water in the formulation.
E. Dosages
Any suitable dosage of drugs can be administered using the formulations of the present invention. The dosage administered will, of course, vary depending upon known factors, such as: the pharmacodynamic characteristics of the particular drug, salt, or combination thereof; the age, health, or weight of the subject; the nature and extent of symptoms; the metabolic characteristics of the therapeutic agent and patient, the kind of concurrent treatment; the frequency of treatment; or the effect desired. Generally, the drug is present in the formulation in an amount ranging from about 0.5 mg/mL to about 3000 mg/mL or up to the solubility limit of the drug in the formulation. In some embodiments, the drug is present in the formulation in an amount ranging from about 10 mg/mL to about 50 mg/mL. In other embodiments, the drug is present in the formulation in an amount ranging from about 20 mg/mL to about 50 mg/mL. In still other embodiments, the drug is present in said formulation in an amount ranging from about 5 mg/mL to about 15 mg/mL. In yet other embodiments, the drug is present in the formulation in an amount ranging from about 0.5 mg/mL to about 2 mg/mL. Again, it will be readily apparent to those of skill that the drug dosage can be varied depending on the drug used and the disease, disorder or condition to be treated, and the concentration of the drug in the formulation will vary depending on the drug solubility, dosage, and method of administration.
F. Additional Ingredients/Pharmaceutical Excipients
While the formulations of the present invention are sufficient and useful with a small molecule drug and a biocompatible non-aqueous solvent (see Example 1, Tables 1-2), the formulation can include additional ingredients/pharmaceutical excipients to further develop a formula to have a desired tactile property, viscosity range, or to further protect the drug active. For instance, the formulations can further include any one of, any combination of, or all of an antioxidant (non-limiting examples of which include ascorbic acid, cysteine, methionine, monothioglycerol, sodium thiosulfate, sulfites, BHT, BHA, ascorbyl palmitate, propyl gallate, or vitamin E or any combination thereof); a chelating agent (non-limiting examples of which include EDTA, EGTA, tartaric acid and salts thereof, glycerin, and citric acid and salts thereof); and/or a preservative (non-limiting examples of which include alkyl alcohols, benzyl alcohols, methyl parabens, propyl parabens and mixtures thereof). Further, the formulations of the present invention can also include a non-aqueous protic solvent (non-limiting examples of which include polyethylene glycol (PEG), propylene glycol (PG), polyvinylpyrrolidone (PVP), methoxypropylene glycol (MPEG), glycerol, glycofurol, and mixtures thereof).
G. Kits/Containers
Kits are also contemplated as being used in certain aspects of the present invention. For instance, a formulation of the present invention can be included within a kit. A kit can include a container. In one aspect, for instance, the formulation can be comprised within a container that is ready to parenterally administer to a subject without having to reconstitute or dilute the formulation. That is, the formulation to be administered can be stored in the container and be readily used as needed. The container can be a device. The device can be a syringe, a pen injection device, an auto-injector device, a device that can pump or administer the formulation (e.g., automatic or non-automatic external pumps, implantable pumps, etc.) or a perfusion bag. Suitable pen/auto-injector devices include, but are not limited to, those pen/auto-injection devices manufactured by Becton-Dickenson, Swedish Healthcare Limited (SHL Group), YpsoMed Ag, and the like. Suitable pump devices include, but are not limited to, those pump devices manufactured by Tandem Diabetes Care, Inc., Delsys Pharmaceuticals and the like.
Alternatively, a kit of the present invention can include multiple containers or multiple compartments within a container. Each container or multiple compartments can be used to store, for instance, the biocompatible non-aqueous solvent and the small molecule drug separately. Then, as needed, the solvent and drug can be mixed together and administered immediately or stored for a later time, as needed.
EXAMPLES
The present invention will be described in greater detail by way of specific examples. The following examples are offered for illustrative purposes, and are not intended to limit the invention in any manner. Those of skill in the art will readily recognize a variety of noncritical parameters which can be changed or modified to yield essentially the same results.
Example 1
Solubility and Stability of Diazepam in Biocompatible Non-Aqueous Solvents
Diazepam, a small molecule anti-anxiety/anti-convulsant drug (MW=284.7 g/mol; anhydrous, Sigma-Aldrich, St. Louis, Mo.) powder was mixed with various biocompatible, non-aqueous solvents in 50 mg increments until it no longer dissolved. The maximum solubility of diazepam at this resolution was thus determined, and is reported in Table 1, along with the corresponding injection volume of a 20-mg dose at these concentrations.










TABLE 1






Solubility

Injection


Solvent
(mg/ml)
Solubility
Volume, μl (20 mg)


















NMP
535
Freely Soluble
37.4


DMSO
125
Freely Soluble
160


70:30
 100*
Freely Soluble
200


DMSO:NMP


Benzyl benzoate
125
Freely Soluble
160


Triacetin
 50
Soluble
400


PEG 300
 50
Soluble
400





*Highest concentration tested. Based on diazepam solubility in DMSO and NMP alone, this value is expected to be at least 125 mg/ml.






Table 2 provides definitions for solubility used in Table 1 and in the following tables.










TABLE 2






Parts of Solvent
Solubility Range
Solubility



per 1 Part Solute
(g/ml)
(mg/ml)


















Very Soluble
<1
>1
>1000


Freely Soluble
1-10
 0.1-1.0
100-1000


Soluble
10-30 
0.03-0.1
30-100


Sparingly Soluble
30-100
 0.01-0.03
10-30 


Slightly Soluble
100-1000
0.001-0.01
1-10


Very Slightly
1000-10000
0.0001-0.001
0.1-1  


Soluble


Practically
>10000
<0.0001
<0.1


Insoluble or


Insoluble









Diazepam solutions were prepared at various concentrations and evaluated for stability over one or six months. Solutions in Table 3 were prepared by diluting solubility test samples and were stored in glass vials at ambient conditions, and solutions in Table 4 were prepared using the following process and stored in syringes in stability chambers:

    
    
        (1) Prepare any blended solvents (e.g., 70:30 DMSO:NMP) in their indicated proportions (v/v) and mix.
        (2) Weigh a mass of diazepam powder appropriate for final concentration of 50 or 100 mg/mL.
        (3) Dissolve diazepam powder in approximately 70% final volume solvent in glass volumetric flask fitted with ground glass stopper.
        
            (a) Stir or sonicate solution.
            (b) Requires less than 20 minutes dissolution time.
        
        
        (4) Add solvent complement to bring to final solution volume.
        (5) Stopper the flask and mix end-over-end at least 10 times.
        (6) Verify drug content and purity via RP-HPLC.

All prepared solutions remained clear by visual inspection and no crystals were observed by light microscopy under 100× magnification in the highest concentration solutions presented in Table 3 after 10 days. Drug content and purity were evaluated using a verified USP RP-HPLC method. The absence of particulates was evaluated using visible light spectroscopy to measure transmittance at 630 nm. These data are detailed in Tables 3 and 4.

    
    











TABLE 3







Solvent




(Diazepam
% Purity
%











Concentration,
Two


Transmittance


mg/ml)
Weeks
Three Weeks
One Month
One Month





NMP
99.73/NA/
99.84/99.85/
99.87/99.88/
NA/100/99.8


(200/100/50)
NA
99.86
99.9


DMSO
99.81/NA/
99.76/99.79/
99.8/99.83/
99.5/NA/100


(125/100/50)
NA
99.80
99.85


Benzyl
99.89/NA/
99.88/99.90/
99.91/99.91/
100/99.8/100


Benzoate
NA
99.85
99.86


(125/100/50)


70:30
NA
99.78
99.87
99.5


DMSO:NMP


(50)



















TABLE 4









25° C./60% Relative Humidity
40° C./75% Relative Humidity




















Actual



Actual






Diazepam
Months
Diazepam
%

%
Diazepam
%


Formulation
Concentration
of
Concentration
Drug
%
Transmittance
Concentration
Drug
%
%


Solution
(mg/ml)
Stability
(mg/ml)
Content
Purity
(630 nm)
(mg/ml)
Content
Purity
Transmittance




















DMSO
50
T = 0
51.5
103.0%
100.00%
99.8
51.5
103.0%
100.00%
99.8




One
48.9
97.8%
99.88%
99.8
50.8
101.6%
99.47%
100.0




Three
50.9
101.7%
100.00%
100.0
49.2
98.3%
100.00%
100.0




Six
48.2
96.3%
100.00%
100.0
48.9
97.8%
100.00%
100.0



100
T = 0
102.4
102.4%
100.00%
99.8
102.4
102.4%
100.00%
99.8




One
99.6
99.6%
99.86%
100.0
99.2
99.2%
99.63%
100.0




Three
99.7
99.7%
100.00%
99.8
98.7
98.7%
99.99%
99.8




Six
98.7
98.7%
100.00%
99.8
81.0
81.0%
100.00%
100.0


NMP
50
T = 0
51.1
102.1%
99.80%
100.0
51.1
102.1%
99.80%
100.0




One
50.4
100.8%
99.97%
100.2
50.9
101.8%
99.95%
100.0




Three
50.5
101.0%
99.97%
100.0
50.1
100.1%
99.94%
100.0




Six
50.4
100.8%
99.94%
100.0
101.6
101.6%
99.96%
100.0



100
T = 0
104.3
104.3%
100.00%
99.8
104.3
104.3%
100.00%
99.8




One
102.4
102.4%
99.73%
99.8
103.2
103.2%
99.42%
100.0




Three
103.1
103.1%
99.98%
99.8
104.0
104.0%
99.96%
99.8




Six
103.3
103.3%
99.98%
99.5
103.5
103.5%
99.95%
99.8


70 DMSO/
50
T = 0
52.1
104.2%
99.99%
100.0
52.1
104.2%
99.99%
100.0


30 NMP

One
51.1
102.1%
99.96%
100.5
50.1
100.3%
99.87%
100.0




Three
51.4
102.7%
99.99%
100.0
47.8
95.6%
99.99%
99.8




Six
51.0
102.0%
100.00%
99.5
49.2
98.3%
99.98%
99.8



100
T = 0
103.6
103.6%
99.99%
100.0
103.6
103.6%
99.99%
100.0




One
101.2
101.2%
99.83%
100.5
102.5
102.5%
99.84%
100.7




Three
102.3
102.3%
99.99%
99.8
102.3
102.3%
99.97%
99.8




Six
100.8
100.8%
100.00%
99.8
98.7
98.7%
99.97%
99.5


Benzyl
50
T = 0
50.4
100.7%
99.86%
99.5
50.4
100.7%
99.86%
99.5


Benzoate

One
50.3
100.6%
99.99%
100.0
50.2
100.4%
99.97%
99.5




Three
50.8
101.6%
99.97%
100.0
50.5
100.9%
99.96%
100.0




Six
50.1
100.1%
99.97%
100.0
50.0
100.0%
99.96%
100.0



100
T = 0
101.8
101.8%
100.00%
99.3
101.8
101.8%
100.00%
99.3




One
100.0
100.0%
99.50%
100.0
100.9
100.9%
99.75%
99.5




Three
100.8
100.8%
99.98%
99.9
103.1
103.1%
99.97%
99.8




Six
91.2
91.2%
99.97%
99.1
105.5
105.5%
99.98%
99.1









The formulations in Table 4 were placed into syringes (e.g., Daikyo Crystal Zenith syringes). To fill syringes, 500 μL of formulation was placed into syringes fitted with needle caps. A long (11⁄2-inch) 20-gauge needle) was placed along the inner wall of the syringe barrel and the plunger was guided down into the barrel until the plunger passed the tip of the needle. This allowed air to escape without pushing the sample out of the syringe. Release testing of filled syringes was conducted to determine drug content (RP-HPLC), purity (RP-HPLC) and transmittance (at 630 nm) of the released formulation from the syringe. With the exception of two formulations, all release samples had between 100.1% and 105.2% target drug content, with at least 99.97% purity and at least 99.3% transmittance.
Example 2
Pharmacokinetics of Diazepam Formulations
A study was conducted to establish the pharmacokinetic (PK) profile in rats of four concentrated subcutaneous (SC) preparations of diazepam compared to a control formulation of rectally administered diazepam gel (Diastat, the prevailing at-home treatment for seizures)). Briefly, five jugular vein-cannulated (JVC) female Sprague-Dawley rats were dosed either by SC injection with 10 uL of liquid diazepam test article, or rectally with 200 μL of the control preparation utilizing a positive displacement pipet. Animals were fasted for 12 hours, and a small application of rectal glycerin prior to Diastat dosing were utilized to minimize defecation and expulsion of drug product in control animals. Whole blood samples were collected at 0 (pre), 3, 6, 9, 12, 20, 30, 45 minutes; 1, 1.5, 2, 3, and 4 hours post drug administration in conical tubes pre-loaded with potassium EDTA anti-coagulant. Plasma diazepam was analyzed as described below. Results are presented in FIG. 1. The preclinical study was performed at Southwest Bio-Labs (Las Cruces, N. Mex.). The study design is summarized in Table 5.













TABLE 5





Group
Rats per
Test Article/
Dose
Route of
Target Dose
Sample Time


No.
Group
Formulation
Volume (μl)
Administration
(mg/rat)
Points*





















1
5
Diastat Rectal Gela
200
Rectal
1
0 (pre), 3,




(Control)



6, 9, 12,


2
5
XeriSol TM Diazepam
10
SC
1
20, 30, 45




DMSO



minutes; 1,


3
5
XeriSol TM Diazepam
10
SC
1
1.5, 2, 3,




DMSO:NMO 70:30



and 4 h


4
5
XeriSol TM Diazepam
10
SC
1
post-drug




NMP



admin.


5
5
XeriSol TM Diazepam
10
SC
1




Benzyl Benzoate





aDiastat rectal gel is a non-sterile diazepam gel provided in a prefilled, unit-dose, rectal delivery system. Diastat rectal gel contains 5 mg/mL diazepam, propylene glycol, ethyl alcohol (10%), hydroxypropyl methylcellulose, sodium benzoate, benzyl alcohol (1.5%), benzoic acid and water, pH between 6.5-7.2.






There were a few noteworthy deviations from the study plan. The jugular vein cannulas presented some difficulty to study personnel and did not maintain patency throughout the study. Some blood collections were consequently delayed by a matter of minutes (each actual collection time was recorded by study personnel). Problems with the JVC caused animals in each of the XeriSolTM groups to require blood sampling from the retro-orbital sinus at various time points. One animal each in the Diastat and XeriSolTM DMSO groups were removed from the study due to complete cannula failure (prior to substituting retro-orbital bleeds). Actual collection times were used to generate individual animal time-concentration curves from which pharmacological parameters were derived.

Diazepam plasma concentrations were measured at ICON Development Solutions, LLC (Whitesboro, N.Y.). ICON used an LC/MS/MS method validated for assay of diazepam in rat plasma. Samples were frozen at the preclinical study site and shipped to ICON on dry ice. Average diazepam concentrations for all groups at nominal intervals post-administration are shown in FIG. 1.
Pharmacokinetic parameters were calculated from each individual animal and averaged by treatment group. Standard non-compartmental methods were utilized to perform calculations for Cmax (the maximum diazepam concentration), Tmax (the time that Cmax was observed, relative to dose administration), and AUC (the area under the diazepam concentration versus time curve from time 0 to 240 minutes). Additionally, the parameter T1/2 max was calculated (the time at which one-half maximum concentration was observed). This parameter is useful when Cmax occurs within a broad peak or when levels around Cmax are reached quickly and then sustained, as was observed in some groups. T1/2 max was derived by performing a linear regression on the initial absorption phase of the curves, and using the equation T1/2 max=[(0.5×Cmax)−(y-intercept)]/slope. Analyses of the pharmacokinetic parameters were performed using SAS statistical software. Bioequivalence could not be determined due to incomplete clearance of the XeriSol diazepam formulations at the end of the study. Data are shown in Table 6.











TABLE 6





Group
Cmax, ng/mL
Area under the curve
Tmax, minutes
T1/2 max, minutes







Diastat
285.00 (44.10) 
10380 (5233)
4.5 (1.7)
1.9 (0.4)


NMP
378.34 (467.53)
 31719 (16921)
8.0 (4.2)
3.6 (1.8)


DMSO
89.28 (34.55)
13936 (2591)
129.8 (127.6)
5.1 (3.1)


DMSO/NMP
92.90 (35.20)
14967 (5989)
100.2 (127.6)
3.0 (1.0)


Benzyl
22.06 (15.61)
 4093 (3332)
204.0 (80.5) 
N/A


Benzoate









These data suggest that among the XeriSolTM groups, the order of effectiveness of the formulations is NMP>NMP:DMSO>DMSO>benzyl benzoate. It is clear that of the XeriSolTM formulations, NMP has the most favorable PK profile and is most comparable to the Diastat control. While all the XeriSolTM formulations, with the exception of benzyl benzoate, have increased AUC over Diastat, three of the XeriSolTM formulations fail to reach one third the Cmax of Diastat. XeriSolTM NMP, on the other hand, exceeds the Diastat Cmax by 33%. Diastat did have the shortest Tmax of all groups, but the XeriSolTM formulations raised plasma diazepam in comparably short times, again with the exception of benzyl benzoate. Whereas Tmax is large for all but XeriSolTM NMP, T1/2 max demonstrates that this is an artifact of sustained concentrations of plasma diazepam near (or slightly above) a concentration that was achieved early in the time course (T1/2 max was not calculated for benzyl benzoate, as Cmax was reached in only one animal; plasma diazepam continuously increased in the other four animals).
The differing Cmax's between the XeriSolTM formulations may be solubility-related, as the Cmax trend follows that of diazepam solubility in the solvents. The time to appear in the blood may be governed in part by the time required to dissolve diazepam should a precipitation event occur upon introduction to the aqueous subcutaneous environment—an event more likely with a lower solubility limit in the vehicle. This information could be useful for tailoring the PK profile through solvent combinations.
Regarding the sustained elevation of plasma diazepam in XeriSolTM groups relative to Diastat controls, differences in blood flow might be causative. From a subcutaneous injection site, diazepam presumably would enter the general circulation and have more time to accumulate in the blood vs. draining quite directly from the rectal blood supply to the liver for metabolism, as is likely the case with Diastat. This phenomenon of sustained concentrations would thus be more difficult to control. However, a sustained blood diazepam, occurring in all XeriSolTM groups throughout the duration of the study, while a measure against bioequivalence with Diastat, could prove beneficial for not only the treatment of an active seizure, but also for the prevention of follow-on or cluster seizures. This benefit would be particularly realized in the XeriSolTM NMP formulation, considered in combination with its rapid absorption profile and high Cmax. Such a PK profile could also indicate that XeriSolTM diazepam may be able to attain therapeutic levels of diazepam using less drug substance per dose than Diastat.
Example 3
Solubility of Lorazepam in Biocompatible Non-Aqueous Solvents
Lorazepam, a small molecule anti-anxiety/anti-convulsant agent (MW=321.16 g/mol) was mixed with 1 gram of the following biocompatible, non-aqueous solvent in approximately 10 milligram increments until it no longer dissolved: benzyl benzoate, DMSO, NMP, Triacetin, and PEG 300. Once 50 mg of drug had been added to the solution (and the drug was still completely soluble in the solvent), the increments of drug added in each step increased to approximately 25 mg, and was maintained at approximately 25 mg until the drug no longer dissolved completely in the solution. This allowed the maximum solubility of lorazepam at this resolution to be determined for each of the five biocompatible non-aqueous solvents, as shown in Table 7.











TABLE 7







Solvent
Solubility (mg/mL)
Solubility




















Benzyl Benzoate
10
Sparingly Soluble



DMSO
100
Freely Soluble



NMP
480
Freely Soluble



Triacetin
20
Sparingly Soluble



PEG 300
80
Soluble










Example 4
Solubility of Albuterol Sulfate in Biocompatible Non-Aqueous Solvents
Albuterol sulfate, a small molecule immuno-suppressive/anti-cancer agent (MW=288.35 g/mol) Was mixed with the following biocompatible non-aqueous solvents (benzyl benzoate, DMSO, NMP, 70:30 (v/v) DMSO:NMP, Triacetin, and PEG 300) in amounts sufficient to prepare mixtures of increasing concentration. Specifically, the concentrations examined were 0.1 mg/mL, 1.0 mg/mL, 5 mg/mL, 10 mg/mL, 30 mg/mL, 50 mg/mL, 100 mg/mL, and increasing increments of 50 mg/mL until the small molecule drug no longer dissolved completely in the solvent. Accordingly, this allowed the maximum solubility of albuterol sulfate at this resolution to be determined for each of the six biocompatible non-aqueous solvents, as shown in Table 8.











TABLE 8








Solubility




Solvent
(mg/mL)
Solubility




















Benzyl Benzoate
<0.1
Practically insoluble



DMSO
5
Slightly soluble



NMP
<0.1
Practically insoluble



70:30 DMSO:NMP
5
Slightly soluble



Triacetin
<0.1
Practically insoluble



PEG 300
<0.1
Practically insoluble










Example 5
Solubility of Atropine in Biocompatible Non-Aqueous Solvents
Atropine, a small molecule anti-cholinergic agent (MW=289.4 g/mol) was mixed with the following biocompatible non-aqueous solvents (benzyl benzoate, DMSO, NMP, 70:30 (v/v) DMSO:NMP, Triacetin, and PEG 300) in amounts sufficient to prepare mixtures of increasing concentration. Specifically, the concentrations examined were 0.1 mg/mL, 1.0 mg/mL, 5 mg/mL, 10 mg/mL, 30 mg/mL, 50 mg/mL, 100 mg/mL, and increasing increments of 50 mg/mL until the small molecule drug no longer dissolved completely in the solvent. Accordingly, this allowed the maximum solubility of atropine at this resolution to be determined for each of the six biocompatible non-aqueous solvents, as shown in Table 9.











TABLE 9







Solvent
Solubility (mg/mL)
Solubility




















Benzyl Benzoate
30
Soluble



DMSO
500
Freely soluble



NMP
750
Freely soluble



70:30 DMSO:NMP
650
Freely soluble



Triacetin
5
Slightly soluble



PEG 300
30
Soluble










Example 6
Solubility of Cromolyn Sodium in Biocompatible Non-Aqueous Solvents
Cromolyn sodium, a small molecule mast cell stabilizer (MW=512.3 g/mol) was mixed with the following biocompatible non-aqueous solvents (benzyl benzoate, DMSO, NMP, 70:30 (v/v) DMSO:NMP, Triacetin, and PEG 300) in amounts sufficient to prepare mixtures of increasing concentration. Specifically, the concentrations examined were 0.1 mg/mL, 1.0 mg/mL, 5 mg/mL, 10 mg/mL, 30 mg/mL, 50 mg/mL, 100 mg/mL, and increasing increments of 50 mg/mL until the small molecule drug no longer dissolved completely in the solvent. Accordingly, this allowed the maximum solubility of cromolyn sodium at this resolution to be determined for each of the six biocompatible non-aqueous solvents, as shown in Table 10.











TABLE 10








Solubility




Solvent
(mg/mL)
Solubility




















Benzyl Benzoate
0.1
Very slightly soluble



DMSO
50
Soluble



NMP
0.1
Very slightly soluble



70:30 DMSO:NMP
5
Slightly soluble



Triacetin
0.1
Very slightly soluble



PEG 300
50
Soluble










Example 7
Solubility of Lidocaine in Biocompatible Non-Aqueous Solvents
Lidocaine, a small molecule (MW=234.34 g/mol) was mixed with the following biocompatible non-aqueous solvents (benzyl benzoate, DMSO, NMP, 70:30 (v/v) DMSO:NMP, Triacetin, and PEG 300) in amounts sufficient to prepare mixtures of increasing concentration. Specifically, the concentrations examined were 0.1 mg/mL, 1.0 mg/mL, 5 mg/mL, 10 mg/mL, 30 mg/mL, 50 mg/mL, 100 mg/mL, and increasing increments of 50 mg/mL until the small molecule drug no longer dissolved completely in the solvent. Accordingly, this allowed the maximum solubility of lidocaine at this resolution to be determined for each of the six biocompatible non-aqueous solvents, as shown in Table 11.











TABLE 11







Solvent
Solubility (mg/mL)
Solubility




















Benzyl Benzoate
900
Freely Soluble



DMSO
2000
Very soluble



NMP
1750
Very soluble



70:30 DMSO:NMP
1750
Very soluble



Triacetin
400
Freely soluble



PEG 300
200
Freely soluble










Example 8
Solubility of Rifampicin in Biocompatible Non-Aqueous Solvents
Rifampicin, a small molecule anti-tubercular agent (MW=822.94 g/mol) was mixed with the following biocompatible non-aqueous solvents (benzyl benzoate, DMSO, NMP, 70:30 (v/v) DMSO:NMP, Triacetin, and PEG 300) in amounts sufficient to prepare mixtures of increasing concentration. Specifically, the concentrations examined were 0.1 mg/mL, 1.0 mg/mL, 5 mg/mL, 10 mg/mL, 30 mg/mL, 50 mg/mL, 100 mg/mL, and increasing increments of 50 mg/mL until the small molecule drug no longer dissolved completely in the solvent. Accordingly, this allowed the maximum solubility of rifampicin at this resolution to be determined for each of the six biocompatible non-aqueous solvents, as shown in Table 12.











TABLE 12







Solvent
Solubility (mg/mL)
Soluble




















Benzyl Benzoate
50
Soluble



DMSO
150
Freely soluble



NMP
400
Freely soluble



70:30 DMSO:NMP
150
Freely soluble



Triacetin
5
Slightly soluble



PEG 300
5
Slightly soluble










Example 9
Solubility of Epinephrine Bitartrate in Biocompatible Non-Aqueous Solvents
Epinephrine bitartrate, a small molecule sympathomimetic (MW=333.3 g/mol) was mixed with the following biocompatible non-aqueous solvents (benzyl benzoate, DMSO, NMP, 70:30 (v/v) DMSO:NMP, Triacetin, and PEG 300) in amounts sufficient to prepare mixtures of increasing concentration. Specifically, the concentrations examined were 0.1 mg/mL, 1.0 mg/mL, 5 mg/mL, 10 mg/mL, 30 mg/mL, 50 mg/mL, 100 mg/mL, and increasing increments of 50 mg/mL until the small molecule drug no longer dissolved completely in the solvent. Accordingly, this allowed the maximum solubility of epinephrine bitartrate at this resolution to be determined for each of the six biocompatible non-aqueous solvents, as shown in Table 13.









TABLE 13





Solvent
Solubility (mg/mL)
Solubility

















Benzyl Benzoate
<0.1
Practically insoluble


DMSO
700
Freely soluble


NMP
400
Freely soluble


70:30 DMSO:NMP
500
Freely soluble


Triacetin
<0.1
Practically insoluble


PEG 300
0.1
Very slightly soluble









Example 10
Solubility of Acetylsalicylic Acid in Biocompatible Non-Aqueous Solvents
Acetylsalicylic acid, a small molecule analgesic agent (MW=180.16 g/mol) was mixed with the following biocompatible non-aqueous solvents (benzyl benzoate, DMSO, NMP, 70:30 (v/v) DMSO:NMP, Triacetin, and PEG 300) in amounts sufficient to prepare mixtures of increasing concentration. Specifically, the concentrations examined were 0.1 mg/mL, 1.0 mg/mL, 5 mg/mL, 10 mg/mL, 30 mg/mL, 50 mg/mL, 100 mg/mL, and increasing increments of 50 mg/mL until the small molecule drug no longer dissolved completely in the solvent. Accordingly, this allowed the maximum solubility of acetylsalicylic acid at this resolution to be determined for each of the six biocompatible non-aqueous solvents, as shown in Table 14.











TABLE 14







Solvent
Solubility (mg/mL)
Solubility




















Benzyl Benzoate
30
Soluble



DMSO
2000
Very soluble



NMP
1200
Very soluble



70:30 DMSO:NMP
1450
Very soluble



Triacetin
5
Slightly soluble



PEG 300
5
Slightly soluble










Example 11
Solubility of Beclomethasone Dipropionate in Biocompatible Non-Aqueous Solvents
Beclomethasone dipropionate, a small molecule corticosteroid (MW=521.04 g/mol) was mixed with the following biocompatible non-aqueous solvents (benzyl benzoate, DMSO, NMP, 70:30 (v/v) DMSO:NMP, Triacetin, and PEG 300) in amounts sufficient to prepare mixtures of increasing concentration. Specifically, the concentrations examined were 0.1 mg/mL, 1.0 mg/mL, 5 mg/mL, 10 mg/mL, 30 mg/mL, 50 mg/mL, 100 mg/mL, and increasing increments of 50 mg/mL until the small molecule drug no longer dissolved completely in the solvent. Accordingly, this allowed the maximum solubility of beclomethasone dipropionate at this resolution to be determined for each of the six biocompatible non-aqueous solvents, as shown in Table 15.











TABLE 15







Solvent
Solubility (mg/mL)
Soluble




















Benzyl Benzoate
50
Soluble



DMSO
1700
Very soluble



NMP
1800
Very soluble



70:30 DMSO:NMP
1700
Very soluble



Triacetin
5
Slightly soluble



PEG 300
30
Soluble










Example 12
Solubility of Sumatriptan Succinate in Biocompatible Non-Aqueous Solvents
Sumatriptan succinate, a small molecule anti-migraine drug (MW=413.49 g/mol) was mixed with the following biocompatible non-aqueous solvents (benzyl benzoate, DMSO, NMP, 70:30 (v/v) DMSO:NMP, Triacetin, and PEG 300) in amounts sufficient to prepare mixtures of increasing concentration. Specifically, the concentrations examined were 0.1 mg/mL, 1.0 mg/mL, 5 mg/mL, 10 mg/mL, 30 mg/mL, 50 mg/mL, 100 mg/mL, and increasing increments of 50 mg/mL until the small molecule drug no longer dissolved completely in the solvent. Accordingly, this allowed the maximum solubility of sumatriptan succinate at this resolution to be determined for each of the six biocompatible non-aqueous solvents, as shown in Table 16.









TABLE 16





Solvent
Solubility (mg/mL)
Soluble

















Benzyl Benzoate
<0.1
Practically insoluble


DMSO
350
Freely soluble


NMP
100
Freely soluble


70:30 DMSO:NMP
300
Freely soluble


Triacetin
<0.1
Practically insoluble


PEG 300
0.1
Very slightly soluble









Example 13
Solubility of Diphenhydramine Hydrochloride in Biocompatible Non-Aqueous Solvents
Diphenhydramine hydrochloride, a small molecule anti-histamine drug (MW=291.82 g/mol) was mixed with the following biocompatible non-aqueous solvents (benzyl benzoate, DMSO, NMP, 70:30 (v/v) DMSO:NMP, Triacetin, and PEG 300) in amounts sufficient to prepare mixtures of increasing concentration. Specifically, the concentrations examined were 0.1 mg/mL, 1.0 mg/mL, 5 mg/mL, 10 mg/mL, 30 mg/mL, 50 mg/mL, 100 mg/mL, and increasing increments of 50 mg/mL until the small molecule drug no longer dissolved completely in the solvent. Accordingly, this allowed the maximum solubility of diphenhydramine hydrochloride at this resolution to be determined for each of the six biocompatible non-aqueous solvents, as shown in Table 17.









TABLE 17





Solvent
Solubility (mg/mL)
Soluble

















Benzyl Benzoate
0.1
Very slightly soluble


DMSO
300
Freely soluble


NMP
100
Freely soluble


70:30 DMSO:NMP
150
Freely soluble


Triacetin
0.1
Very slightly soluble


PEG 300
50
Soluble









Example 14
Solubility of Fluconazole in Biocompatible Non-Aqueous Solvents
Fluconazole, a small molecule anti-fungal drug (MW=306.27 g/mol) was mixed with the following biocompatible non-aqueous solvents (benzyl benzoate, DMSO, NMP, 70:30 (v/v) DMSO:NMP, Triacetin, and PEG 300) in amounts sufficient to prepare mixtures of increasing concentration. Specifically, the concentrations examined were 0.1 mg/mL, 1.0 mg/mL, 5 mg/mL, 10 mg/mL, 30 mg/mL, 50 mg/mL, 100 mg/mL, and increasing increments of 50 mg/mL until the small molecule drug no longer dissolved completely in the solvent. Accordingly, this allowed the maximum solubility of fluconazole at this resolution to be determined for each of the six biocompatible non-aqueous solvents, as shown in Table 18.











TABLE 18







Solvent
Solubility (mg/mL)
Solubility




















Benzyl Benzoate
5
Slightly soluble



DMSO
900
Freely soluble



NMP
800
Freely soluble



70:30 DMSO:NMP
850
Freely soluble



Triacetin
5
Slightly soluble



PEG 300
50
Soluble










Example 15
Solubility of Tobramycin in Biocompatible Non-Aqueous Solvents
Tobramycin, a small molecule aminoglycoside antibiotic (MW=467.51 g/mol) was mixed with the following biocompatible non-aqueous solvents (benzyl benzoate, DMSO, NMP, 70:30 (v/v) DMSO:NMP, Triacetin, and PEG 300) in amounts sufficient to prepare mixtures of increasing concentration. Specifically, the concentrations examined were 0.1 mg/mL, 1.0 mg/mL, 5 mg/mL, 10 mg/mL, 30 mg/mL, 50 mg/mL, 100 mg/mL, and increasing increments of 50 mg/mL until the small molecule drug no longer dissolved completely in the solvent completely in the solvent. Accordingly, this allowed the maximum solubility of tobramycin at this resolution to be determined for each of the six biocompatible non-aqueous solvents, as shown in Table 19.









TABLE 19





Solvent
Solubility (mg/mL)
Solubility

















Benzyl Benzoate
<0.1
Practically insoluble


DMSO
<0.1
Practically insoluble


NMP
<0.1
Practically insoluble


70:30 DMSO:NMP
<0.1
Practically insoluble


Triacetin
0.1
Very slightly soluble


PEG 300
0.1
Very slightly soluble









Example 16
Solubility of Cyclophosphamide Monohydrate in Biocompatible Non-Aqueous Solvents
Cyclophosphamide monohydrate, a small molecule immuno-suppresive/anti-cancer agent (MW=279.10 g/mol) was mixed with the following biocompatible non-aqueous solvents (benzyl benzoate, DMSO, NMP, 70:30 (v/v) DMSO:NMP, Triacetin, and PEG 300) in amounts sufficient to prepare mixtures of increasing concentration. Specifically, the concentrations examined were 0.1 mg/mL, 1.0 mg/mL, 5 mg/mL, 10 mg/mL, 30 mg/mL, 50 mg/mL, 100 mg/mL, and increasing increments of 50 mg/mL until the small molecule drug no longer dissolved completely in the solvent. Accordingly, this allowed the maximum solubility of cyclophosphamide monohydrate at this resolution to be determined for each of the six biocompatible non-aqueous solvents, as shown in Table 20.











TABLE 20







Solvent
Solubility (mg/mL)
Soluble




















Benzyl Benzoate
100
Freely soluble



DMSO
2800
Very soluble



NMP
2100
Very soluble



70:30 DMSO:NMP
2700
Very soluble



Triacetin
150
Freely soluble



PEG 300
100
Freely soluble










* * *
All of the ingredients, compositions, or methods disclosed and claimed in this specification can be made and executed without undue experimentation in light of the present disclosure. While the ingredients, compositions, or methods of this invention have been described in terms of particular embodiments, it will be apparent to those of skill in the art that variations may be applied to the active ingredients, compositions, or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention.

## Claims

1. A method for treating or preventing anxiety, muscle spasms, or seizures, the method comprising parenterally administering to a subject in need thereof a stable liquid formulation comprising: (a) a biocompatible solvent consisting of dimethylsulfoxide (DMSO) or a mixture of DMSO and n-methyl pyrrolidone (NMP); and (b) a small molecule drug, or a salt thereof, solubilized within the solvent, wherein the small molecule drug is diazepam, and wherein diazepam is present in the liquid formulation in an amount up to its solubility limit in the formulation, wherein the liquid formulation comprises less than 5% by weight residual water, and wherein a volume of the liquid formulation to be parenterally injected is 3 ml or less.

2. The method of claim 1, further comprising the injectable volume within a device for dispensing the liquid formulation.

3. The method of claim 2, wherein the device is a syringe, a pen injection device, an auto-injector device, an external or implantable pump, or a perfusion bag.

4. The method of claim 1, wherein the liquid formulation comprises 50 mg/ml to 300 mg/ml of diazepam.

5. The method of claim 1, wherein the volume of the liquid formulation to be parenterally injected is from 0.1 μl to 1 μl.

6. The method of claim 1, wherein the volume of the liquid formulation to be parenterally injected is from 1 μl to 10 μl.

7. The method of claim 1, wherein the volume of the liquid formulation to be parenterally injected is from 10 μl to 1 ml.

8. The method of claim 1, wherein the liquid formulation is not diluted prior to administration.