Rifabutin treatment methods, uses and compositions

Abstract

A rifabutin formulation produced from rifabutin powder in the presence of an acid, water, and a solvent suitable for promoting dissolution of the rifabutin. A method of preparing a rifabutin formulation, the method comprising: preparing a solution comprising a solvent, water, and an acid; and adding the solution to rifabutin powder, thereby dissolving the rifabutin in the solution. A method of preparing a rifabutin formulation, the method comprising: preparing a solution comprising water and an acid; and adding the solution to a rifabutin solution in a solvent, thereby producing an aqueous rifabutin formulation. A method of treating a bacterial infection in a subject, the method comprising administering a therapeutically effective amount of rifabutin in an injectable formulation or by inhalation.

Description

[0001] Related Applications

[0002] This application claims the benefit of and priority to U.S. Provisional Patent Application Serial Nos. 62 / 902,019 (filed September 18, 2019), 62 / 899,257 (filed September 12, 2019), 62 / 941,160 (filed November 27, 2019), and 62 / 977,659 (filed February 17, 2020), the contents of each of which are incorporated herein in their entirety. Technical Field

[0003] The present invention generally relates to formulations containing the antibiotic rifabutin, methods of making such formulations, and methods of using such formulations to treat bacterial infections. Background Art

[0004] Millions of people die each year from bacterial infections, and this number is increasing due to the spread of antibiotic-resistant bacterial strains. For example, according to official estimates, more than 100,000 people die each year from antibiotic-resistant bacterial infections in the United States, the European Union, and India alone, and some experts believe that official statistics are a serious underestimate because the full impact of antibiotic resistance is still unknown. Unfortunately, the process of developing new antibiotics has slowed to a crawl in recent decades, and many existing antibiotics have problems that limit their effectiveness.

[0005] One existing antibiotic that has yet to realize its full therapeutic potential is rifabutin, also known as LM427 and Although rifabutin is active against a wide range of bacteria, its poor water solubility makes it difficult to obtain the antibiotic in effective doses for treating infection (except Rifabutin is a drug that is used to treat bacterial infections. However, rifabutin is not effective in preventing the development of resistance. Rifabutin is a drug that is used to treat bacterial infections. However, rifabutin is not effective in preventing the development of resistance. Rifabutin is used to treat bacterial infections. However, ri ... Summary of the invention

[0006] The present invention provides pharmaceutical formulations containing high concentrations of rifabutin. Preferred compositions of the present invention include rifabutin powder formulated in water, solvent and acid. The combination of the present invention allows dissolution of rifabutin at high concentrations. The formulated solution can be diluted without restriction to make the composition suitable for the desired route of administration.

[0007] The formulations of the present invention allow for the delivery of effective amounts of rifabutin by routes of administration that were not possible with previous rifabutin-containing compositions. For example, the formulations of the present invention enable rifabutin to be provided parenterally, including intravenously or by inhalation. In addition, the formulations of the present invention eliminate the need to lyophilize rifabutin and then reconstitute it for administration, which is a relatively expensive process.

[0008] In another aspect of the invention, rifabutin is prepared as a powder having a shelf life that is the same as the shelf life of the rifabutin active pharmaceutical ingredient (API). As described in detail below, the rifabutin formulation of the present invention preferably comprises rifabutin powder dissolved in an organic solvent.

[0009] According to the present invention, highly concentrated rifabutin formulations are rapidly obtained from any rifabutin API and used as is or further diluted arbitrarily with sterile water or a pharmaceutically acceptable solution. The formulations of the present invention can be used to treat a variety of conditions caused by or associated with bacterial infection, such as, but not limited to, bacteremia, meningitis, ventilator-associated bacterial pneumonia (VABP), hospital-acquired bacterial pneumonia (HABP), and periprosthetic joint infection (PJI).

[0010] In one aspect, the present invention provides a non-oral formulation of rifabutin made by preparing a solution in the presence of an acid suitable for promoting the dissolution of rifabutin. The solution preferably comprises a solvent and water in a proportion suitable for the intended use of the formulation.

[0011] The formulation of the present invention is suitable for any non-oral administration route. The formulation is suitable for parenteral, intravenous, intra-arterial administration or pulmonary delivery. The formulation is also suitable for administration by inhalation or by injection.

[0012] The formulation of the present invention is a reconstituted solution that may need to be diluted before non-oral administration. The formulation of the present invention comprises a solvent and water in a defined ratio. The ratio can be a v / v ratio. The solution can comprise a solvent and distilled water in a ratio of about 9:1 to about 1:9, about 9:1 to about 1:4, about 9:1 to about 1:2, about 9:1 to about 1:1, about 4:1 to about 1:9, about 4:1 to about 1:4, about 4:1 to about 1:2, about 4:1 to about 1:1, about 2:1 to about 1:9, about 2:1 to about 1:4, about 2:1 to about 1:2 or about 2:1 to about 1:1. The solution can comprise a solvent and distilled water in a ratio of about 9:1, about 4:1, about 2:1, about 1:1, about 1:2, about 1:4 or about 1:9.

[0013] The solvent may be polyoxyethylene sorbitan monooleate (Tween 80), sorbitan monooleate polyoxyethylene sorbitan monolaurate (Tween 20), polyethylene glycol (PEG), propylene glycol, N-methyl-2-pyrrolidone (NMP), glycerol, ethanol, dimethylacetamide (DMA), diethylene glycol monoethyl ether (transcutol HP) or dimethyl isosorbide (DMI).

[0014] The acid may be hydrochloric acid, methanesulfonic acid, phosphoric acid, L-tartaric acid, D-glucuronic acid, L-malic acid, D-gluconic acid, L-lactic acid, acetic acid or L-aspartic acid.

[0015] The reconstituted solution of the present invention preferably contains about 250 mg / ml (1:1 solvent / water) or about 166.7 mg / ml (1:2 solvent / water), but the concentration of the reconstituted solution may be as high as about 300 mg / ml. In certain embodiments, a more dilute solution is required and is obtained by adding more water to the solvent. For example, rifabutin with a solvent / water ratio of 1:4 will produce a solution of about 50 mg / ml. However, this dilution will take extra time to dissolve the rifabutin powder. Alternatively, rifabutin can be dissolved in the solvent and the reconstituted solution is then obtained without further modification. Generally, for IV solutions, it is desirable to keep the rifabutin / solvent ratio as low as possible. Suitable ranges are provided herein.

[0016] The formulations of the present invention are effective in treating bacterial infections. The infection may include one or more of: Acinetobacter baumannii, Campylobacter jejuni, Chlamydia trachomatis, Haemophilus ducreyi, Haemophilus influenzae, Helicobacter pylori, Mycobacterium chelonae, Mycobacterium kansasii, Mycobacterium leprae, Mycobacterium tuberculosis, Mycobacterium avium, Mycobacterium intracellulare, Neisseria gonorrhoeae, Neisseria meningitidis, Staphylococcus, Streptococcus (e.g., Group A Streptococcus), and Toxoplasma gondii, or any other pathogens that are sensitive to rifabutin.

[0017] The amount of acid relative to rifabutin may be between 1 and 3 molar equivalents or between 1 and 2 molar equivalents. The amount of acid relative to rifabutin may be 1 molar equivalent.

[0018] The w / v ratio of rifabutin to solvent may be about 4:1 to about 1:4, about 2:1 to about 1:3, or about 1:1 to about 1:2. The w / v ratio of rifabutin to solvent may be about 4:1, about 3:1, about 2:1, about 1:1, about 1:2, about 1:3, or about 1:4.

[0019] In another aspect, the present invention provides a method for preparing a non-oral formulation of rifabutin, which is performed by preparing a solution comprising a solvent and distilled water, adding an acid to the solution, and introducing the solution into rifabutin powder, thereby dissolving rifabutin in the solution.

[0020] In another aspect, the present invention provides a method for preparing a non-oral formulation of rifabutin, which is carried out by preparing a solution of rifabutin in a solvent and an aqueous solution of an acid, and then mixing the two solutions.

[0021] The formulation may have any of the properties described above for the formulation. The acid and solvent may be any of those described above. Water and solvent may be combined in any of the proportions described above.

[0022] The methods of the present invention comprise unlimited dilution of the formulated rifabutin solution so as to render the composition suitable for the desired route of administration into a pharmaceutically acceptable diluent (such as, but not limited to, sterile water, sodium chloride (ie, saline) solution, dextrose in water, lactated Ringer's solution).

[0023] The step of dissolving rifabutin may comprise swirling, stirring or agitating the solution. The step of dissolving rifabutin may be performed for a defined time. The step of dissolving rifabutin may be performed for about 5 minutes, about 10 minutes, about 15 minutes, about 20 minutes, about 30 minutes, about 45 minutes, or about 60 minutes.

[0024] Rifabutin may be provided in the form of a solid powder.

[0025] Rifabutin may be provided as a solution in a solvent.

[0026] In another aspect, the present invention provides a method of treating a bacterial infection in a subject by administering a therapeutically effective amount of a non-oral formulation of rifabutin.

[0027] The bacterial infection may comprise one or more of: Acinetobacter baumannii, Campylobacter jejuni, Chlamydia trachomatis, Haemophilus ducreyi, Haemophilus influenzae, Helicobacter pylori, Mycobacterium chelonae, Mycobacterium kansasii, Mycobacterium leprae, Mycobacterium tuberculosis, Mycobacterium avium, Mycobacterium intracellulare, Neisseria gonorrhoeae, Neisseria meningitidis, Staphylococcus, Streptococcus (e.g., Group A Streptococcus), and Toxoplasma gondii, or any other pathogen that is sensitive to rifabutin.

[0028] The formulation may have any of the properties described above for the formulation.

[0029] The formulation may be administered parenterally, intravenously or by inhalation.

[0030] Various aspects of the present disclosure provide for the use of rifabutin, an acid, a solvent, and a diluent in the manufacture of a medicament for treating a bacterial infection.

[0031] In certain embodiments, the diluent is water.

[0032] In certain embodiments, the w / v ratio of rifabutin to solvent may be about 4:1, about 3:1, about 2:1, about 1:1, about 1:2, about 1:3, or about 1:4.

[0033] In certain embodiments, the w / v ratio of rifabutin to solvent is about 1:2.

[0034] In certain embodiments, the solvent is polyoxyethylene sorbitan monooleate (Tween 80), sorbitan monooleate polyoxyethylene sorbitan monolaurate (Tween 20), polyethylene glycol (PEG), propylene glycol, N-methyl-2-pyrrolidone (NMP), glycerol, ethanol, dimethylacetamide (DMA), diethylene glycol monoethyl ether (transcutol HP), or dimethyl isosorbide (DMI).

[0035] In certain embodiments, the solvent is DMI or transcutol HP.

[0036] In certain embodiments, the solvent and water are present in a ratio of about 9:1 to about 1:9, about 9:1 to about 1:4, about 9:1 to about 1:2, about 9:1 to about 1:1, about 4:1 to about 1:9, about 4:1 to about 1:4, about 4:1 to about 1:2, about 4:1 to about 1:1, about 2:1 to about 1:9, about 2:1 to about 1:4, about 2:1 to about 1:2, or about 2:1 to about 1:1.

[0037] In certain embodiments, the solvent and water are present in a ratio of about 1:1 to about 1:2.

[0038] In certain embodiments, the acid is hydrochloric acid, methanesulfonic acid, phosphoric acid, L-tartaric acid, D-glucuronic acid, L-malic acid, D-gluconic acid, L-lactic acid, acetic acid, or L-aspartic acid.

[0039] In certain embodiments, the acid may be D-glucuronic acid.

[0040] In certain embodiments, the acid can be acetic acid.

[0041] In certain embodiments, the amount of acid relative to rifabutin is between 1 and 3 molar equivalents or between 1 and 2 molar equivalents.

[0042] In certain embodiments, the amount of acid relative to rifabutin may be 1 molar equivalent.

[0043] In certain embodiments, the molar ratio of rifabutin to acid is about 1:1.

[0044] In certain embodiments, the w / v ratio of rifabutin to solvent may be about 4:1 to about 1:4, about 2:1 to about 1:3, or about 1:1 to about 1:2.

[0045] In certain embodiments, the bacterial infection is Acinetobacter baumannii, Campylobacter jejuni, Chlamydia trachomatis, Haemophilus ducreyi, Haemophilus influenzae, Helicobacter pylori, Mycobacterium chelonae, Mycobacterium kansasii, Mycobacterium leprae, Mycobacterium tuberculosis, Mycobacterium avium, Mycobacterium intracellulare, Neisseria gonorrhoeae, Neisseria meningitidis, Staphylococcus, Streptococcus (e.g., Group A Streptococcus), or Toxoplasma gondii.

[0046] In another aspect, the present invention provides a formulation comprising rifabutin, an acid, water, and a solvent suitable for facilitating dissolution of the rifabutin.

[0047] The formulation may contain any rifabutin / solvent ratio, any solvent / water ratio, or any rifabutin / acid ratio described above.

[0048] The formulation may contain any of the solvents or any of the acids described above.

[0049] The formulation can contain any concentration of rifabutin, for example, about 250 mg / ml, about 200 mg / ml, about 150 mg / ml, about 100 mg / ml, about 50 mg / ml, about 20 mg / ml, about 10 mg / ml, about 5 mg / ml, about 2.5 mg / ml, about 1 mg / ml, at least about 250 mg / ml, at least about 200 mg / ml, at least about 150 mg / ml, at least about 100 mg / ml, at least about 50 mg / ml, at least about 20 mg / ml, at least about 10 mg / ml, at least about 5 mg / ml, at least about 2.5 mg / ml, at least about 1 mg / ml, about 250 mg / ml, about 200 mg / ml, at least about 150 mg / ml, at least about 100 mg / ml, at least about 50 mg / ml, at least about 20 mg / ml, at least about 10 mg / ml, at least about 5 mg / ml, at least about 2.5 mg / ml, at least about 1 mg / ml, about 2 .5mg / ml to about 250mg / ml, about 5mg / ml to about 250mg / ml, about 10mg / ml to about 250mg / ml, about 20mg / ml to about 250mg / ml, about 50mg / ml to about 250mg / ml, about 100mg / ml to about 250mg / ml, about 1mg / ml to about 200mg / ml, about 2.5mg / ml to about 200mg / ml, about 5mg / ml to about 200mg / ml, about 10mg / ml to about 200mg / ml, about 20mg / ml to about 200mg / ml, about 50mg / ml to about 200mg / ml or about 100mg / ml to about 200mg / ml. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 is a schematic diagram of a method for preparing an injectable rifabutin solution or rifabutin for inhalation according to an embodiment of the present invention.

[0051] Figure 2 is a schematic diagram of the analytical method for rifabutin formulations.

[0052] Figure 3 is a graph showing the solubility of rifabutin in the formulations.

[0053] Figure 4 is a graph showing the solubility of rifabutin in the formulations. DETAILED DESCRIPTION

[0054] Rifabutin and the challenges of administering rifabutin

[0055] The present invention provides compositions and methods for preparing solutions containing rifabutin suitable for parenteral or inhalation administration. Importantly, the present invention enables the intravenous administration of rifabutin in large doses. Rifabutin intravenous formulations allow the compound to be delivered with greater efficiency and efficacy than can be achieved with existing oral rifabutin formulations. In particular, the present invention discloses the use of a water / solvent mixture in the presence of an acid as a pharmaceutically acceptable reconstitution solution for rifabutin powder to rapidly prepare a stable, highly concentrated reconstituted solution that can then be diluted with additional water for injection or with a pharmaceutically acceptable diluent without restriction to make the composition suitable for the desired route of administration.

[0056] The formulations of the present invention are associated with the requirement that high concentrations of rifabutin at the site of infection are necessary to achieve appropriate pharmacokinetic (PK) parameters (e.g., area under the curve (AUC) and C max ) are optimal and these parameters are necessary to achieve maximum clinical efficacy and prevent resistance in the treatment of bacterial infections against which rifabutin is active.

[0057] Rifabutin is a dark red-purple powder with a molecular formula of C 46 H 62 NO 11 , molecular weight is 847.02, and its structure is as follows:

[0058]

[0059] Rifabutin has broad-spectrum antibacterial activity. It is significantly more active than rifampin against MAC, Mycobacterium tuberculosis, and Mycobacterium leprae. It is also active against most atypical mycobacteria (including Mycobacterium kansasii); however, Mycobacterium chelonae is relatively resistant. Rifabutin is also active against Staphylococci, Group A Streptococci, Neisseria gonorrhoeae, Neisseria meningitidis, Haemophilus influenzae, Haemophilus ducreyi, Campylobacter jejuni, Helicobacter pylori, Chlamydia trachomatis, Toxoplasma gondii, and Acinetobacter baumannii.

[0060] In healthy adult volunteers, a nominal therapeutic oral dose of 300 mg rifabutin produced a mean C max The PK of rifabutin was linear after single PO administration of 300, 450, and 600 mg to healthy volunteers, with C max In the range of 0.4 to 0.7 mg / L (Rifabutin Product Monograph). In studies of HIV-infected patients receiving the recommended daily dose of rifabutin (300 mg / day), steady-state plasma concentrations were C max =0.59±0.33 mg / L, AUC is 8.6±8.2 mg*h / L (Hafner et al., 1998). Since rifabutin is approximately 90% protein bound, the free drug concentration after oral administration is very low. In healthy adult volunteers, at least 53% of the oral dose is absorbed, and in a multiple dose study, the absolute bioavailability evaluated in HIV-positive patients was 20% on day 1 and 12% on day 28.

[0061] In the closely related rifamycin molecules (e.g., rifampin), microbial killing is related to the ratio of the area under the concentration-time curve to the minimum inhibitory concentration (MIC) (AUC / MIC), whereas inhibition of resistance is related to the free peak concentration (C max Ratio to MIC (C max / MIC) but not the duration of rifampicin concentration above MIC. In addition, the duration of post-antibiotic effect was also related to C max / MIC ratio is most closely related. Gumbo T, Louie A, Deziel MR, Liu W, Parsons LM, Salfinger M, Drusano GL, "Concentration-dependent Mycobacterium tuberculosis killing and prevention of resistance by rifampin", "Antimicrob Agents Chemother", 2007, 51 (11): 3781-8, the contents of which are incorporated herein by reference. Therefore, in order to achieve microbial killing and prevent the emergence of drug resistance in the clinical field, high plasma and / or high local concentrations of rifabutin are required.

[0062] The emergence of multi-antimicrobial resistance in pathogenic bacteria has become a major public health threat as fewer or no effective antimicrobial agents are available for infections caused by these bacteria. Both Gram-positive and Gram-negative bacteria are affected by the emergence and rise of antimicrobial resistance.

[0063] Life-threatening infections caused by these pathogens are best treated in a hospital setting, using optimized dosing regimens that typically involve parenteral administration and, in some cases, the additional use of aerosolized antibiotics.

[0064] In this context, the intravenous (IV) and inhalation (IN) routes of administration have several advantages over the oral route in terms of achieving high cure rates:

[0065] a) By the oral route, only a variable fraction reaches the systemic circulation; the rest of the drug either passes through the gastrointestinal (GI) tract without being absorbed or undergoes a first-pass effect, i.e., metabolic transformation in the liver, resulting in excretion of drug metabolites via the bile or kidneys.

[0066] b) Oral route, C max and t max (Implement C max time) is limited by the absorption rate of the drug in the GI tract.

[0067] c) The absorption rate in humans varies widely, depending on the patient's age, the presence of concomitant diseases and the progression of infectious diseases in the patient.

[0068] d) In contrast, with the IV route, the drug enters the bloodstream directly, max is instant, and C maxThis can be controlled by the concentration of drug infused and the time over which it is infused. By definition, AUC is the maximum value achievable relative to any other route of administration.

[0069] e) In contrast, via the IN route, the drug goes directly to the lungs and C max The distribution in the lungs can be controlled by the drug concentration and the particle size produced by the specific nebulizer.

[0070] Both IV and IN routes allow rifabutin to achieve higher AUC / MIC and C max / MIC, which is critical for efficacy during the treatment of bacterial infections that are sensitive to the effects of rifabutin and for preventing the development of resistance. The IV route of administration allows optimization of these parameters in the plasma and any compartment where the drug can be properly distributed, and is therefore suitable for the treatment of infections such as, for example, bacteremia, meningitis, periprosthetic joint infection (PJI), and severe lung infections (e.g., ventilator-associated bacterial infection (VABP) and hospital-acquired bacterial infection (HABP)); in contrast, higher local concentrations can be achieved in the lungs via the IN route to treat any bacterial lung infection, in all of which the physician prefers to achieve extremely high drug lung concentrations without having to expose other body compartments to excessive drug levels. Alternatively, the physician may decide to use rifabutin in combination with oral or parenteral antibiotics via the IN route.

[0071] The present invention includes rifabutin formulations for intravenous (IV) administration. In another embodiment of the present invention, rifabutin is administered intravenously (IV) or by inhalation (IN).

[0072] Compositions and formulations containing rifabutin

[0073] The present invention provides compositions comprising formulations wherein free base rifabutin is dissolved in water / solvent and acid.

[0074] The composition can be provided in the form of a pharmaceutically acceptable salt, such as a non-toxic acid addition salt, which is a salt of an amino group formed with an inorganic acid or an organic acid, such as but not limited to hydrochloric acid, hydrobromic acid, phosphoric acid, sulfuric acid and perchloric acid; the organic acid is such as but not limited to acetic acid, maleic acid, tartaric acid, citric acid, succinic acid, methanesulfonic acid, glucuronic acid, malic acid, gluconic acid, lactic acid, aspartic acid or malonic acid.

[0075] In some embodiments, pharmaceutically acceptable salts include, but are not limited to, adipate, alginate, ascorbate, aspartate, benzenesulfonate, benzoate, bisulfate, borate, butyrate, camphorate, camphorsulfonate, citrate, cyclopentanepropionate, digluconate, dodecylsulfate, ethanesulfonate, formate, fumarate, glucoheptonate, glycerophosphate, gluconate, hemisulfate, heptanoate, hexanoate, hydroiodide, 2-hydroxy-ethanesulfonate, lactobionate, lactate, laurate, lauryl sulfate, malate, maleate, malonate, methanesulfonate, 2-naphthalenesulfonate, nicotinate, nitrate, oleate, oxalate, palmitate, pamoate, pectinate, persulfate, 3-phenylpropionate, phosphate, picrate, pivalate, propionate, stearate, succinate, sulfate, tartrate, thiocyanate, p-toluenesulfonate, undecanoate, valerate, and the like. Preferably, hydrochloric acid, methanesulfonic acid, phosphoric acid, L-tartaric acid, D-glucuronic acid, L-malic acid, D-gluconic acid, L-lactic acid, acetic acid or L-aspartic acid can be used. Most preferably, acetic acid, L-lactic acid, D-glucuronic acid or D-glucuronic acid is used.

[0076] The pharmaceutical composition can be administered by injection, infusion, implantation (intravenous, intramuscular, subcutaneous, etc.) or by inhalation of dosage forms, formulations or via suitable delivery devices or implants containing conventional non-toxic pharmaceutically acceptable carriers, solvents, diluents and adjuvants. The formulation and preparation of such compositions are well known to those skilled in the art of pharmaceutical formulation.

[0077] The compositions of the present invention for parenteral use may be provided in unit dosage form (e.g., single-dose ampoules and vials), in multiple vials containing multiple doses and to which suitable preservatives (see below) may be added, in pre-filled syringes, or in pre-filled IV bags. The pharmaceutical compositions described herein may be in a form suitable for sterile injection. Figure 1 As shown in , to prepare such a composition, a solution of water in a solvent and an acid is added to rifabutin in powder form to facilitate dissolution. Alternatively, such a composition can be prepared by preparing a solvent containing rifabutin and mixing it with an aqueous solution containing an acid.

[0078] Thus, the present invention provides a method for preparing a rifabutin intravenous formulation. The method may comprise preparing a solution containing a solvent and distilled water. Preferably, the solution is in a ratio of 1:1 or 1:2. The solvent may be any solvent, but is preferably DMI or transcutol HP. An acid may be added to the solution. The acid may be suitable for promoting the dissolution of rifabutin. The acid may be any acid, but is preferably acetic acid or D-glucuronic acid. The solution containing the acid may be added to rifabutin powder. Thus, the acid dissolves rifabutin in the aqueous solution.

[0079] The rifabutin solution may be added to a pharmaceutically acceptable diluent. The diluent may be 0.9% saline.

[0080] For example, to prepare a 20 mg / ml solution of rifabutin in 4% DMI, a 1:1 dimethyl isosorbide (DMI) solution in distilled water is first prepared. Then, 0.169 ml of glacial acetic acid can be added to 9.831 ml of 1:1 DMI / water solution to form a reconstitution solvent (RS). Then, 1 ml of RS is added to 250 mg of rifabutin to make a 250 mg / ml solution. Stir or shake the RS-rifabutin solution until rifabutin dissolves to form a dark crimson solution. Complete dissolution should occur within about 15-20 minutes. Then, the concentrated solution is diluted with 11.5 ml of water to make a final 20 mg / ml rifabutin solution in 4% DMI. The pH of the final solution is between 5 and 6.

[0081] In another example of preparing an intravenous solution of 2.5 mg / ml rifabutin in 0.5% DMI / 0.9% sodium chloride solution, a 1:1 distilled water solution of dimethyl isosorbide is first prepared. Then, 0.169 ml of glacial acetic acid can be added to 9.831 ml of the 1:1 DMI / water solution to form RS. Then, 1 ml of RS is added to 250 mg of rifabutin to make a 250 mg / ml solution. Stir or shake the RS-rifabutin solution until the rifabutin is completely dissolved (about 15-20 minutes). Then, the concentrated solution is diluted with 99 ml of 0.9% saline for injection to make a final 2.5 mg / ml rifabutin solution in 0.9% saline containing 0.5% DMI, with a pH between 5.0 and 6.0.

[0082] In another example, to prepare an intravenous solution of 5 mg / ml rifabutin in a 1% transcutol HP / 0.9% sodium chloride solution, first prepare a 1:2 transcutol HP distilled water solution. Then, 0.169 ml of glacial acetic acid can be added to 14.831 ml of the 1:2 transcutol HP / water solution to form RS. Then, 1.5 ml of RS is added to 250 mg of rifabutin to make a 166.7 mg / ml solution. Stir or shake the RS-rifabutin solution until rifabutin is completely dissolved (about 15-20 minutes). Then, the concentrated solution is diluted with 48.5 ml of 0.9% saline for injection to make a final 5 mg / ml rifabutin 1% transcutol HP 0.9% saline solution, the pH of which is between 5.0 and 6.0.

[0083] In another example, a 40 mg / ml rifabutin intravenous solution in 8% DMI / 0.9% sodium chloride solution was prepared using a 250 mg rifabutin solution in 0.5 ml DMI to which was added 0.5 ml of a 114.6 mg / ml D-glucuronic acid solution in distilled water. After vortexing for 5 minutes, the resulting 250 mg / ml RS-rifabutin solution was diluted with 5.25 ml of 0.9% saline for injection to make a final 40 mg / ml rifabutin solution in 8% DMI in 0.9% saline with a pH between 5.0 and 6.0.

[0084] Depending on the patient's needs and clinical condition, administration of the composition by IV administration may be more advantageous than oral administration because it allows rapid introduction of the antibiotic into the systemic circulation, provides complete bioavailability, allows for better control of pharmacokinetic parameters that drive pharmacological efficacy, and avoids stability and absorption issues in the gastrointestinal tract.

[0085] The typical dose of rifabutin is that which achieves the rifabutin C max A dose of plasma or local levels >2 mg / L but <50 mg / L and AUC of 10 mg*h / L <200 mg*h / L.

[0086] The rifabutin solution can be further diluted with a pharmaceutically acceptable diluent. For example, a 20 mg / mL rifabutin IV solution can be further diluted with 0.9% saline to obtain a lower concentration of rifabutin for delivery of a lower concentration solution to a subject. The rifabutin IV formulation disclosed herein may also require filtration. If desired, the concentrated solution or the final rifabutin solution can be filtered.

[0087] The formulations of the present invention can be used for any parenteral administration. For example, the composition can be formulated for injection or infusion. The injection or infusion can be subcutaneous or intravenous. Preferably, the composition is formulated for intravenous administration. Preferably, the composition is formulated for intravenous or inhalation administration. Therefore, the formulations of the present invention may also contain a pharmaceutically acceptable diluent. The pharmaceutically acceptable diluent may have a concentration sufficient to deliver the therapeutically effective amount of rifabutin in the IV formulation to a patient suffering from an infection. The pharmaceutically acceptable diluent may be saline or sterile water. Preferably, the diluent is 0.9% saline. The solution may be administered with a therapeutically effective amount of rifabutin to treat a patient suffering from an infection.

[0088] It should be noted that the various formulations of the invention described herein may be used with any of the methods of the invention, and thus the methods are not limited to any single formulation.

[0089] Method for preparing formulations containing rifabutin

[0090] The present invention provides a method for preparing a rifabutin formulation.

[0091] Figure 1 is a schematic diagram showing a method for preparing an injectable rifabutin solution or rifabutin for inhalation according to an embodiment of the present invention. An intravenous rifabutin formulation can be manufactured by a process comprising the following: preparing a sterile pharmaceutically acceptable reconstitution solution comprising a solvent and distilled water in a ratio of 1:1 in the presence of an acid suitable for promoting the dissolution of rifabutin. Rifabutin can be present in a solid form or in the form of a powder soluble in a liquid medium. Rifabutin can be dissolved in an aqueous solution of a solvent and distilled water. Rifabutin can be soluble in an aqueous solution of 50% solvent (i.e., 1:1 solvent-distilled water) in the presence of an acid.

[0092] Rifabutin is soluble in an aqueous solution of 33.3% solvent (ie, 1:2 solvent-distilled water) in the presence of acid.

[0093] The formulation may be suitable for any non-oral route of administration. The formulation may be suitable for parenteral, intravenous, intra-arterial administration. The formulation may be suitable for administration by inhalation.

[0094] The formulation may be a reconstituted solution that requires dilution prior to parenteral administration. The formulation may be a reconstituted solution suitable for parenteral administration.

[0095] Dissolving can include mixing solvent and distilled water in a defined ratio. The ratio can be a v / v ratio. The solution can include solvent and distilled water in a ratio of about 9:1 to about 1:9, about 9:1 to about 1:4, about 9:1 to about 1:2, about 9:1 to about 1:1, about 4:1 to about 1:9, about 4:1 to about 1:4, about 4:1 to about 1:2, about 4:1 to about 1:1, about 2:1 to about 1:9, about 2:1 to about 1:4, about 2:1 to about 1:2, or about 2:1 to about 1:1. The solution can include solvent and distilled water in a ratio of about 9:1, about 4:1, about 2:1, about 1:1, about 1:2, about 1:4, or about 1:9.

[0096] The solvent may be polyoxyethylene sorbitan monooleate (Tween 80), sorbitan monooleate polyoxyethylene sorbitan monolaurate (Tween 20), polyethylene glycol (PEG), propylene glycol, N-methyl-2-pyrrolidone (NMP), glycerol, ethanol, dimethylacetamide (DMA), diethylene glycol monoethyl ether (transcutol HP) or dimethyl isosorbide (DMI).

[0097] The acid may be hydrochloric acid, methanesulfonic acid, phosphoric acid, L-tartaric acid, D-glucuronic acid, L-malic acid, D-gluconic acid, L-lactic acid, acetic acid or L-aspartic acid.

[0098] The formulation may comprise diluting the solution containing rifabutin into a diluent. The diluent may be sterile water, sodium chloride (i.e., saline) solution, dextrose water, or lactated Ringer's solution. The sodium chloride solution may be a 0.9% sodium chloride solution. The dextrose solution may be a 5% dextrose solution or a 10% dextrose solution.

[0099] The resulting solution may require further dilution in a pharmaceutically acceptable solvent, such as, but not limited to, sterile water, mannitol (e.g., 3-5% mannitol, 3% mannitol, 4% mannitol, 4.3% mannitol, and 5% mannitol), phosphates, acetates, additional tartrates, saline (e.g., normal saline (0.9%), 1 / 2 normal saline (0.45%), and 0.5% saline), etc. For intravenous formulations, normal saline (0.9%) is a preferred diluent or carrier.

[0100] Rifabutin can be reconstituted in a solution containing an acid in an amount between 1 and 3 molar equivalents in a solvent and water mixture in a v / v ratio of about 9:1 to about 1:9. The w / v ratio of rifabutin to solvent can be 4:1 to 1:4. The dissolution time for obtaining the formulation can be less than 60 minutes. In particular, the amount of acid can be 1 molar equivalent, the acid can be acetic acid or D-glucuronic acid, the solvent can be DMI or transcutol HP mixed with water in a 1:1 or 1:2 v / v ratio, the w / v ratio of rifabutin to solvent can be 1:2, and the dissolution time is less than 20 minutes.

[0101] The formulation (i.e., reconstituted rifabutin solution) can be used as is, or can be manufactured by diluting it into a defined volume of diluent. The volume of the diluent can be expressed relative to the volume of the reconstituted solution. The volume of the diluent can be about 1.0 to about 2.0 volumes, about 1.25 to about 2.25 volumes, about 1.5 to about 2.5 volumes, about 1.75 to about 2.75 volumes, about 2.0 to about 3.0 volumes, about 1.80 to about 2.10 volumes, about 1.90 to about 2.05 volumes, or about 1.95 to about 2.0 volumes of the reconstituted rifabutin solution. The reconstituted rifabutin solution can be added to about 20.5 to about 30 volumes, about 21 to about 29 volumes, about 22 to about 28 volumes, about 23 to about 27 volumes, about 23 to about 26 volumes, about 23 to about 25 volumes, about 23 to about 24 volumes, about 22.5 to about 23.5 volumes, or about 23.0 to about 23.5 volumes of 0.9% saline for injection. Thus, one volume of diluent results in a final solution of about 125 mg / ml, 4 volumes result in a final solution of about 50 mg / ml, 9 volumes result in a final solution of about 25 mg / ml, 24 volumes result in a final solution of about 10 mg / ml, and 99 volumes result in a final solution of about 2.5 mg / ml. The skilled artisan understands how to make a solution with any desired final concentration.

[0102] The formulation can contain rifabutin in any suitable concentration (eg, the concentrations described above).

[0103] The formulation may contain DMI at any concentration (eg, those from the dilutions described above).

[0104] The formulation may contain any concentration of transcutol HP (eg, those derived from the dilutions described).

[0105] The amount of acid relative to rifabutin may be between 1 and 3 molar equivalents or between 1 and 2 molar equivalents. The amount of acid relative to rifabutin may be 1 molar equivalent.

[0106] The w / v ratio of rifabutin to solvent may be about 4:1 to about 1:4, about 2:1 to about 1:3, or about 1:1 to about 1:2. The w / v ratio of rifabutin to solvent may be about 4:1, about 3:1, about 2:1, about 1:1, about 1:2, about 1:3, or about 1:4.

[0107] The method may comprise dissolving the rifabutin by vortexing, stirring or agitating the solution. The dissolving step may be performed for a defined time. The dissolving step may be performed for about 5 minutes, about 10 minutes, about 15 minutes, about 20 minutes, about 30 minutes, about 45 minutes, or about 60 minutes.

[0108] Treatments for bacterial infections

[0109] The present invention provides a method for treating bacterial infection. The method comprises administering a rifabutin liquid formulation to a subject suffering from a bacterial infection. The liquid formulation may comprise rifabutin, a solvent and an acid.

[0110] The formulation can be provided by intravenous, intraarterial or pulmonary administration. The formulation can be provided by inhalation or injection.

[0111] The liquid formulation can be a solution of rifabutin and a diluent to be administered intravenously to a subject with a bacterial infection. The formulation for IV administration can include a pharmaceutically acceptable solvent. The method can include administering an IV formulation of any rifabutin formulation described herein to a subject with a bacterial infection.

[0112] IV formulations containing rifabutin can be administered with another antibiotic or therapeutic agent. Sequential administration or alternating administration can include providing only an IV formulation containing rifabutin for a period of time and only providing another therapeutic agent for a period of time. Sequential administration can include providing overlapping time of IV formulations containing rifabutin and formulations containing another therapeutic agent to the subject at the same time. Exclusive time and overlapping time can independently be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 2 months, 3 months, 4 months, 5 months, 6 months, 8 months, 10 months, 12 months, 18 months or 24 months. Alternatively, the pharmaceutical formulations of the present invention or soluble components in the formulation can contain rifabutin and another therapeutic agent.

[0113] Without wishing to be bound by theory, any formulation of the invention may be used in any method of the invention.

[0114] In another aspect of the invention, a method comprises treating a bacterial infection in a subject. The method may comprise administering a therapeutically effective amount of a formulation comprising rifabutin or a salt thereof. The rifabutin formulation may be formulated for intravenous administration. The intravenous formulation is manufactured by a process comprising preparing a solution of a solvent and distilled water in a ratio of 1:1 in the presence of an acid suitable for promoting dissolution of the rifabutin. Preferably, the solvent is DMI. Preferably, the solvent is transcutol HP. Preferably, the intravenous formulation is a solution of approximately 2.5 mg / mL of rifabutin in 0.5% DMI and 0.9% sodium chloride solution.

[0115] In another embodiment, the method may comprise providing a subject with a bacterial infection with an IV formulation of rifabutin or a salt thereof in combination with another therapeutic agent. The IV formulation may comprise a pharmaceutically acceptable solvent. The therapeutic agent may be present in a formulation for IV administration.

[0116] The IV formulation containing rifabutin and the formulation containing another therapeutic agent can be provided or administered simultaneously, sequentially provided or administered in any order, or provided or administered in an alternating manner. Sequential administration or alternating administration can include providing only the IV formulation containing rifabutin for a period of time and only providing the formulation containing another therapeutic agent for a period of time. Sequential administration can include overlapping time of providing the IV formulation containing rifabutin and the formulation containing another therapeutic agent to the subject at the same time. Exclusive time and overlapping time can independently be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 2 months, 3 months, 4 months, 5 months, 6 months, 8 months, 10 months, 12 months, 18 months or 24 months.

[0117] In another embodiment, rifabutin is filled into glass vials and sterilized using one of the procedures for terminal sterilization. These procedures are well known to those skilled in the art and can be performed using gamma radiation or heat sterilization.

[0118] A sterile solution of 50:50 water for injection and a solvent containing about 1 molar equivalent of the acid is then added to the sterile rifabutin to form a concentrated reconstituted solution.

[0119] In another embodiment, the reconstituted rifabutin formulation is sterile filtered.

[0120] In another embodiment, the diluted rifabutin formulation is sterile filtered.

[0121] Examples

[0122] Example 1

[0123] Preliminary evaluation of solubility in solvents: To determine whether a pharmaceutically acceptable solvent can dissolve rifabutin powder and at what concentration, a sufficient volume of solvent to achieve a maximum target solubility of 300 mg / ml was added to a small aliquot of rifabutin powder. After stirring at room temperature for 24 hours, the sample was centrifuged and the supernatant was analyzed by HPLC. The rifabutin chromatographic peak area was compared to the titration curve. The results of this preliminary screening are reported in Table 1.

[0124] Table 1. Solubility results in formulation media

[0125] Solvent / Solution 24-hour solubility (mg / ml) Polyethylene glycol 400 (PEG400) ≥110 Propylene glycol ≥92 N-Methyl-2-pyrrolidone (NMP) ≥190 Dimethylacetamide (DMA) ≥204 transcutol HP ≥206 glycerin 0.4 Tween 80 (1% w / w aqueous solution) 1.3 Povidone K12 (5% w / w aqueous solution) 0.5 Dimethyl Isosorbide(DMI) ≥245 Saline 0.9% 0.3 Acetate buffer pH 4 (USP) 11.3 Phosphate buffer pH 6 (USP) 0.3 Phosphate buffer pH 8 (USP) 0.2 Borate Buffer pH 10 (USP) 1.9 Ethanol (Literature) 30

[0126] The results of the "thermodynamic" solubility screening indicated that dimethyl isosorbide (DMI) was the best solvent. Although interesting, the 24-hour solubility data is irrelevant in the reconstitution of antibiotic powders because the reconstitution solvent must be able to dissolve the antibiotic within a few minutes, which is practically enough for the operator to prepare rifabutin for injection or inhalation.

[0127] Rifabutin can be dissolved in DMI at concentrations ≥ 250 mg / ml, but the dissolution time was shown to be longer than might be acceptable. In addition, since the DMI-rifabutin solution separates from the aqueous solution, the DMI rifabutin solution cannot be diluted with a pharmaceutically acceptable solution (e.g., saline).

[0128] Unexpectedly, the addition of acid to the DMI / water solution allowed the rifabutin powder to dissolve rapidly, and the highly concentrated reconstituted rifabutin solution could be diluted arbitrarily with water or 0.9% saline without any precipitation of rifabutin.

[0129] Example 2

[0130] Small-scale solubility screening of solvents and acids: Rifabutin powder (amounts between 100 and 200 mg) was weighed into a 1.8 ml glass vial. Examples of reconstitution solutions were prepared by mixing different solvents in the amounts specified in Table 2 and water containing different acids. The solution was stirred for 15 minutes at RT using a magnetic stir bar and vortexed briefly. The sample was filtered using a centrifugal filter (0.2 μm PTFE filter) and the concentration of the reconstituted solution was determined by HPLC analysis. The rifabutin chromatographic peak area was compared with the titration curve and the results are reported in Table 2.

[0131] Table 2. Small scale solubility screening

[0132]

[0133] Table 3. Solubility of rifabutin reconstituted solution at t=0 and t=24 hours

[0134]

[0135] Table 4. Solubility and pH of reconstituted rifabutin solutions diluted with 0.9% saline at t=0 and t=24 hours

[0136]

[0137]

[0138] Example 3:

[0139] Reconstitution of rifabutin and large-scale evaluation of further dilution with 0.9% saline: 1.50 g (1.77 mmol) of rifabutin powder was weighed into a 40 mL glass vial. An equimolar amount of acid (1.77 mmol) dissolved in 6 mL of dimethyl isosorbide / water 50 / 50 (v / v) was added. The solution was vortexed for 30 seconds, stirred vigorously for 15 minutes at RT using a magnetic stir bar, and then vortexed again for 30 seconds.

[0140] The samples were filtered using a syringe and filter (0.2 μm PTFE filter) and the concentration of the reconstituted rifabutin solution was determined by HPLC analysis. Aliquots (1 mL) of the undiluted solution were stored at RT and 5° C. for 24 hours.

[0141] Figure 2 Schematic diagram showing the analytical method for rifabutin formulations. Aliquots (500 μL) of the filtrate were diluted 10-fold and 100-fold in 0.9% saline. These dilutions were prepared in triplicate. The diluted samples were visually inspected to determine if there was immediate precipitation and filtered after 15 minutes. The concentration of API was determined by HPLC analysis and the pH was recorded. The diluted samples were stored at RT for 24 hours.

[0142] After 24 hours of storage, diluted and undiluted samples were reanalyzed by HPLC analysis to determine API concentration, and pH values ​​were recorded.

[0143] The experimental details, results and recorded pH values ​​for the solubility tests of the undiluted samples are shown in Tables 5, 6 and 7 and in Figure 3 and 4 Represented graphically in .

[0144] Table 5. Concentrations and pH of reconstituted rifabutin solutions at t=0 and stored at 5°C and room temperature for 24 hours

[0145]

[0146] Figure 3 is a graph showing the solubility of rifabutin in the formulation. Larger scale undiluted samples were analyzed at t0 (blue bars), after 24 hours at room temperature (red bars) and after 24 hours at 5°C (green bars).

[0147] Table 6. Concentrations and pH* of a nominal 25 mg / ml rifabutin solution stored at room temperature for 24 hours.

[0148]

[0149] *The experiment has been performed in a set of three times.

[0150] For solutions generated from acetic acid, L-lactic acid, D-gluconic acid, and D-glucuronic acid, the osmolarity of these solutions were 632, 644, 622, and 645 mOsm / kg, respectively.

[0151] Table 7. Concentrations and pH* of a nominal 2.5 mg / ml rifabutin solution stored at room temperature for 24 hours.

[0152]

[0153] *The experiment has been performed in a set of three times.

[0154] For the solutions generated from acetic acid, L-lactic acid, D-gluconic acid, and D-glucuronic acid, the osmolarity of these solutions were 323, 319, 316, and 318 mOsm / kg, respectively.

[0155] Figure 4 is a graph showing the solubility of rifabutin in the formulations.

[0156] Diluted samples were analyzed at t0 (blue bars, 10-fold dilution; grey bars 100-fold dilution) and after 24 h at room temperature (orange bars, 10-fold dilution; yellow bars 100-fold dilution).

[0157] Example 4

[0158] Reconstitution of rifabutin from a rifabutin solution in transcutol HP and further dilution with 0.9% saline: 1.50 g (1.77 mmol) of rifabutin powder was weighed into a 40 mL glass vial. 3 ml of DMI or 3 ml of transcutol HP were added and the very concentrated suspension was vortexed for about 6 hours and 18 hours, respectively, to obtain a very thick solution. The solution was sterile filtered through a 0.2 μm filter (PTFE filter).

[0159] To 1 ml aliquots of two solutions containing about 500 mg (about 0.590 mmol) of rifabutin was added 1 ml of an aqueous solution containing 0.590 mmol of acetic acid under gentle vortexing. Perfect solutions were formed instantly. Analysis before and after filtration (0.2 μm PTFE filter) showed that the titers of all solutions were similar, consistent with the results reported in Example 3.

[0160] To another 1 ml aliquot of the two solutions containing about 500 mg (about 0.590 mmol) of rifabutin was added 5 ml of a 1:4 water / 0.9% saline solution containing 0.590 mmol of acetic acid. A perfect solution was formed instantly. Analysis before and after filtration (0.2 μm PTFE filter) showed that the titers of all solutions were similar, about 46.7 to 48.2 mg / ml.

[0161] Example 5

[0162] Analytical method and sample preparation for solubility determination: The dilution for solubility determination (Dilution 1 21-fold) was prepared by adding 25 μL of the stock solution to 500 μL of 0.1% TFA in acetonitrile. If necessary, a second dilution (441-fold dilution) was prepared by adding 25 μL of dilution 1 to 500 μL of 0.1% TFA in acetonitrile.

[0163] LCMS method

[0164] HPLC: Agilent 1200

[0165] Detector 1: DAD, set at 276 nm

[0166] Detector 2: Mass spectrometer

[0167] HPLC conditions:

[0168] Column: Sunfire C18 (100 x 4.6 mm x 3.5 μm)

[0169] Column temperature: 35°C

[0170] Flow cell: 10mm optical path

[0171] Mobile phase A: 0.1% TFA in water

[0172] Mobile phase B: 0.1% TFA in acetonitrile

[0173] Flow rate: 1.0ml / min

[0174] HPLC mobile phase gradient. Time (min) Mobile phase A (%) Mobile phase B (%) 0 90 10 9 10 90 10 90 10 11 90 10

[0175] The retention time of rifabutin was 6.8-6.9 minutes. The concentration of the components in the solution was calculated using the peak area observed from the UV detector for the compound of interest. It was confirmed that there was no interference with the components of the vehicle.

[0176] Tables 3 and 5 report the concentration of rifabutin in dimethyl isosorbide / water 50 / 50 (v / v) or transcutol HP / water 33.3 / 66.7 (v / v) solutions containing 1 molar equivalent of acid, freshly prepared and after storage at room temperature (RT) or 5°C for 24 hours.

[0177] The reconstituted solution can be stored at RT and 5 °C for 24 h.

[0178] Tables 4, 6 and 7 report the concentrations of rifabutin after dilution up to 100-fold in 0.9% saline and storage for 24 hours at RT. The pH and osmolarity of the solutions were also recorded.

[0179] The reconstituted solution may be diluted without limit to render the composition suitable for the desired route of administration.

[0180] The final pH of the reconstituted solution diluted with 0.9% saline depends on the pKa of the acid used, and preferred acids have pKa values ​​greater than 2, preferably greater than 3. Preferably, such acids are D-glucuronic acid, D-gluconic acid, L-lactic acid and acetic acid. Most preferably, the acid is acetic acid or D-glucuronic acid.

[0181] Example 6

[0182] Reconstitution of rifabutin from rifabutin bulk solution in DMI and further dilution with 0.9% saline:

[0183] Preparation of Vial 1: 1200 ml of DMI was heated at 40 ° C in a 5L glass jar and 600 g (0.708 mole) of rifabutin powder was added in batches under stirring at 40 ° C. Complete dissolution was obtained in about 6 hours and the solution was returned to room temperature. The solution was then filtered through a PVDF (polyvinylidene fluoride), nylon or PTFE (polytetrafluoroethylene) 0.22 μm sterile filter. A volume of solution equivalent to 500 mg (0.590 mmol) of rifabutin was transferred to a 10 ml sterile and pyrogen-free vial via a sterile tube and the vial was sealed with a Fluorotec rubber stopper and a reversible top seal. Additionally or alternatively, the vial was terminally sterilized in an autoclave at 121 ° C for 20 minutes. This procedure was repeated starting from two different rifabutin batches.

[0184] Analytical and stability data after terminal sterilization are reported in Tables 8 and 9, respectively.

[0185] Preparation of Vial 2: A 4% w / v solution of acetic acid in sterile water for injection was transferred via sterile tubing to a 10 ml sterile and depyrogenated vial and the vial was sealed with a Fluorotec rubber stopper and flip top seal and terminally sterilized in an autoclave.

[0186] Reconstitution of rifabutin prior to use: 1 ml of a sterile 4% w / v acetic acid (0.66 mmol) aqueous solution for injection was withdrawn from vial 2 with the aid of a 1 ml syringe and added to vial 1 with gentle swirling.

[0187] Dilution of reconstituted rifabutin solution in 0.9% saline:The total volume of the reconstituted solution was brought to 10 ml by adding a sterile solution of 0.9% NaCl solution (saline for injection) to give a final rifabutin concentration of 50 mg / ml.

[0188] The analytical data are listed in Table 10.

[0189] Alternatively, the reconstituted solution may be withdrawn from the vial with the aid of a syringe and injected directly into the saline bag for infusion.

[0190] Table 8. Analysis of vials 1 prepared from two different rifabutin batches

[0191]

[0192]

[0193] *Change in impurity content of rifabutin compared to vial 1 of rifabutin drug substance (API). Data are % impurities and are reported as % impurities in vial 1 - % impurities in API.

[0194] Table 9. Stability results for vial 1 stored at 2-8°C and 25°C ± 2°C / 60% RH ± 5% RH

[0195]

[0196] * Changes in impurity levels of rifabutin in vial 1 after storage under different conditions. Data are % impurities and are reported as % impurities in vial 1 at day 15, day 30 and day 90 - % impurities in vial 1 at day 0.

[0197] Table 10. Analysis of reconstituted solutions after dilution to 50 mg / ml 0.9% saline

[0198]

[0199] *Change in impurity content of rifabutin after reconstitution and dilution with 0.9% saline. Data are % impurity and are reported as % impurity in reconstituted / diluted solution - % impurity in vial 1.

[0200] Example 7

[0201] Analytical methods and sample preparation for stability studies and impurity determination

[0202] HPLC conditions

[0203]

[0204] Sample preparation

[0205] blank solution : Mobile phase was as is.

[0206] Test Solution 1 - For determination of rifabutin concentration in bulk solution:

[0207] Transfer 5 mg of rifabutin to the DMI solution, accurately weigh, transfer to a 10 mL volumetric flask, and dilute to a certain volume with acetonitrile. Transfer 1.5 ml of the resulting solution to a 50 ml volumetric flask, dilute to a certain volume with mobile phase, and mix (0.5 mg / ml).

[0208] Test Solution 2 - For determination of vial contents:

[0209] After removing the vial flip cap, transfer about 5 ml of ACN in the sealed vial by using a 10 ml syringe. Then, the resulting solution is transferred to a 50 ml volumetric flask and washed at least 5 times with ACN by adding the washing solution to the 50 ml volumetric flask, so as to accurately recover the total amount of solution in the vial. Then, remove the seal and stopper, and clean the vial twice again. Then, dilute the volume with ACN.

[0210] Finally, the resulting solution was diluted from 1 ml to 20 ml with mobile phase and mixed (0.5 mg / ml).

[0211] Standard solution : About 25 mg of accurately weighed Rifabutin CRS was transferred to a 50 mL volumetric flask. 5 mL of acetonitrile was added and the solution was diluted to a certain volume with the mobile phase and mixed (0.5 mg / ml).

[0212] Diluted standard solution : Dilute 1 ml of rifabutin standard solution to 100 ml with mobile phase (0.005 mg / ml).

[0213] Resolution Solution : Dissolve about 10 mg of Rifabutin CRS in 2 ml of MeOH, add 1 ml of 2N NaOH, and let the solution stand for about 4 minutes. Add 1 ml of 2N HCl and dilute the solution to 50 ml with mobile phase.

[0214] System suitability

[0215] - About Resolution Solution : The chromatogram shows that the RRTs of the main peak of the degradation product, the two secondary peaks of the degradation product and the main peak of rifabutin are about 0.5, 0.6, 0.8 and 1.0 respectively. The resolution between the eluted rifabutin peak with a relative retention time of about 0.8 and the degradation product peak is not less than 1.3.

[0216] - About Standard Preparation : The column efficiency is not less than 2000 theoretical plates, and the relative standard deviation of repeated injections is not greater than 2.0%.

[0217] Calculation for Test Solution 1

[0218] The amount of rifabutin (in mg) per gram of sample was calculated using the following formula:

[0219]

[0220] in

[0221] C = standard concentration (mg / mL)

[0222] P = potency of standard (μg / mg),

[0223] W = sample weight (g)

[0224] AT = sample peak area

[0225] AS = Average peak area of ​​standard products

[0226] Calculate the percentage of each impurity using the following formula:

[0227]

[0228] in

[0229] C = concentration of diluted standard (mg / mL)

[0230] P = potency of standard (μg / mg)

[0231] W = sample weight (g)

[0232] AI = Impurity Peak Area

[0233] AS = Standard peak area

[0234] R = mg of rifabutin per gram of sample, calculated concentration (mg / g)

[0235] Calculation for Test Solution 2

[0236] Calculate the amount of rifabutin (in grams) in each vial using the following formula:

[0237]

[0238] in

[0239] C = standard concentration (mg / mL)

[0240] P = potency of standard (μg / mg),

[0241] W = sample weight (g)

[0242] AT = sample peak area

[0243] AS = Average peak area of ​​standard products

[0244] Calculate the percentage of each impurity using the following formula:

[0245]

[0246] in

[0247] C = concentration of diluted standard (mg / mL)

[0248] P = potency of standard (μg / mg)

[0249] W = sample weight (g)

[0250] AI = Impurity Peak Area

[0251] AS = Standard peak area

[0252] R = mg rifabutin per vial

[0253] Incorporated by Reference

[0254] Throughout this disclosure, other documents, such as patents, patent applications, patent publications, journals, books, papers, web page content, have been cited and referenced. All of these documents are hereby incorporated by reference into this document for all purposes.

[0255] Equivalence

[0256] Various modifications of the invention and numerous other embodiments thereof, in addition to those shown and described herein, will become apparent to those skilled in the art from the entire contents of this document (including references to scientific and patent literature cited herein). The subject matter herein contains important information, illustrations, and guidance that can be adapted to practice the invention in its various embodiments and their equivalents.

Claims

1. A rifabutin formulation produced from rifabutin powder in the presence of an acid, water and a solvent suitable for promoting dissolution of said rifabutin, wherein the w / v ratio of rifabutin to solvent is 1:2, the molar ratio of rifabutin to acid is equimolar, and the v / v ratio of solvent to water is from 1:1 to 1:2, The acid is selected from the group consisting of: hydrochloric acid, methanesulfonic acid, phosphoric acid, L-tartaric acid, D-glucuronic acid, L-malic acid, D-gluconic acid, L-lactic acid and acetic acid, and the solvent is selected from the group consisting of: dimethyl isosorbide, DMA and transcutol HP; wherein: When the solvent is dimethyl isosorbide, the acid is selected from the group consisting of hydrochloric acid, methanesulfonic acid, phosphoric acid, L-tartaric acid, D-glucuronic acid, L-malic acid, D-gluconic acid, L-lactic acid and acetic acid, When the solvent is DMA, the acid is D-glucuronic acid or acetic acid, When the solvent is transcutol HP, the acid is selected from the group consisting of: D-glucuronic acid and acetic acid.

2. The formulation according to claim 1, wherein the formulation comprises rifabutin at a concentration between 50 mg / ml and 250 mg / ml.

3. The formulation according to claim 1, wherein the formulation is diluted to produce a composition suitable for a desired route of administration.

4. A method for preparing a rifabutin formulation, the method comprising: preparing a solution comprising a solvent, water and an acid; the acid being selected from the group consisting of hydrochloric acid, methanesulfonic acid, phosphoric acid, L-tartaric acid, D-glucuronic acid, L-malic acid, D-gluconic acid, L-lactic acid and acetic acid, the solvent being selected from the group consisting of dimethyl isosorbide, DMA and transcutol HP; and The rifabutin powder is dissolved in the solution, wherein the w / v ratio of rifabutin to the solvent is 1:2, the molar ratio of rifabutin to the acid is equimolar, and the v / v ratio of the solvent to water is 1:1 to 1:2; wherein: When the solvent is dimethyl isosorbide, the acid is selected from the group consisting of hydrochloric acid, methanesulfonic acid, phosphoric acid, L-tartaric acid, D-glucuronic acid, L-malic acid, D-gluconic acid, L-lactic acid and acetic acid, When the solvent is DMA, the acid is D-glucuronic acid or acetic acid, When the solvent is transcutol HP, the acid is selected from the group consisting of: D-glucuronic acid and acetic acid.

5. A method for preparing a rifabutin formulation, the method comprising: preparing a solution comprising water and an acid; The acid is selected from the group consisting of hydrochloric acid, methanesulfonic acid, phosphoric acid, L-tartaric acid, D-glucuronic acid, L-malic acid, D-gluconic acid, L-lactic acid and acetic acid; and adding the solution to a solution of rifabutin in a solvent selected from the group consisting of dimethyl isosorbide, DMA and transcutol HP to produce an aqueous rifabutin formulation; The w / v ratio of rifabutin to solvent is 1:2, the molar ratio of rifabutin to acid is equimolar, and the solvent is The v / v ratio of the agent to water is 1:1 to 1:2; wherein: When the solvent is dimethyl isosorbide, the acid is selected from the group consisting of hydrochloric acid, methanesulfonic acid, phosphoric acid, L-tartaric acid, D-glucuronic acid, L-malic acid, D-gluconic acid, L-lactic acid and acetic acid, When the solvent is DMA, the acid is D-glucuronic acid or acetic acid, When the solvent is transcutol HP, the acid is selected from the group consisting of: D-glucuronic acid and acetic acid.

6. The rifabutin formulation according to claim 1 for use in the preparation of a bacterial strain in a subject Use in a medicament for treating an infection, wherein the medicament is administered by injection or inhalation.

Images