| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | February 13, 2001 |
| PATENT TITLE |
Mometasone furoate suspensions for nebulization |
| PATENT ABSTRACT | An aqueous nebulizer suspension contains water, mometasone furoate monohydrate, a nonionic surfactant, a soluble salt and optionally a pH buffer. The suspension may be prepared by ultrasonication or jet milling techniques |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | October 6, 1998 |
| PATENT PARENT CASE TEXT | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. A nebulizer suspension consisting essentially of water, mometasone furoate monohydrate, a nonionic surfactant, about 0.2 to about 2 weight percent of sodium chloride or potassium chloride and, optionally, a pH buffer. 2. The suspension of claim 1, wherein mometasone furoate monohydrate comprises about 50 micrograms to about 5 milligrams, per milliliter. 3. The suspension of claim 1, wherein the surfactant comprises a Polysorbate surfactant. 4. The suspension of claim 1, wherein the surfactant comprises Polysorbate 80. 5. The suspension of claim 1, wherein the surfactant comprises a Poloxamer surfactant. 6. The suspension of claim 1, wherein the surfactant comprises about 50 micrograms to about 1 milligram, per milliliter. 7. The suspension of claim 1, wherein the salt comprises sodium chloride. 8. A method for treating airway disorders, comprising administering by nebulization to surfaces of the airway a treatment-effective amount of the suspension of claim 1. 9. The suspension of claim 1, which includes a pH buffer. 10. The suspension of claim 9, wherein the buffer comprises a citric acid-citrate buffer. 11. The suspension of claim 9, wherein the buffer maintains aqueous phase pH values about 3 to about 7. 12. The suspension of claim 9, wherein the buffer maintains aqueous phase pH values about 3 to about 6. 13. The suspension of claim 9, wherein the buffer maintains aqueous phase pH values about 4 to about 5. 14. The suspension of claim 1, wherein solid particles have average sizes less than about 5 .mu.m. 15. The suspension of claim 1, wherein solid particles have average sizes less than about 2 .mu.m. 16. A process for producing a nebulizer suspension, comprising combining ingredients consisting essentially of water, mometasone furoate monohydrate, a nonionic surfactant, about 0.2 to about 2 weight percent of sodium chloride or potassium chloride and, optionally, a pH buffer and subjecting the combination to particle size reduction by ultrasonication or by jet milling. 17. The process of claim 16, wherein the combination includes a pH buffer. 18. The process of claim 16, wherein particle size reduction is continued to produce solid particles having sizes less than about 10 .mu.m. 19. The process of claim 16, wherein particle size reduction is continued to produce solid particles having average sizes less than about 5 .mu.m. 20. The process of claim 16, wherein particle size reduction is continued to produce solid particles having average sizes less than about 2 .mu.m. 21. A method for treating airway disorders, comprising administering by nebulization to surfaces of the airway a treatment-effective amount of a suspension prepared by the process of claim 16. |
| PATENT DESCRIPTION |
INTRODUCTION TO THE INVENTION The present invention relates to aqueous suspensions of water-insoluble pharmaceutical substances, and more particularly to suspensions of substances intended for inhalation therapy. Use of inhaled therapeutic substances has become common for the treatment of airway disorders, such disorders including, without limitation thereto, asthma, infections, emphysema and various inflammatory conditions. Substances commonly delivered to the lower airway surfaces, that is, the trachea, bronchial tree and lungs, by oral or nasal inhalation include bronchodilators, corticosteroids, anti-infectives and anti-inflammatory medicaments. Various methods have been used for such delivery, including pressurized metered dose inhalers, dry powder inhalers and nebulizers. Nebulizers are considered to be instruments generating very fine particles of a liquid in a gas. As is very well known, particles intended for treatment of the lower airway, i.e., the bronchial tree or the lungs, will generally be less than 10 micrometers in the largest dimension, to prevent unwanted deposition onto surfaces of the mouth and pharynx, and more preferably will be less than 5 .mu.m. In addition, particles much smaller than about 0.5 .mu.m in the largest dimension frequently are not easily deposited at the desired location, and a large fraction of these simply will be exhaled by a patient. For these reasons, it is generally desired to produce particles which average 1-7 .mu.m in their largest dimension, while preferably minimizing production of particles having sizes either less than about 0.5 or greater than about 10 .mu.m. The more preferred average particle sizes are in the range of 0.5-5 .mu.m. Nebulization, although used more infrequently than other drug delivery techniques, has certain advantages for special patient groups, such as young children and the very infirm. Although somewhat cumbersome equipment is needed and there may be more stringent cleaning requirements than exist for some of the more popular delivery techniques, no particular patient skill or coordination is required: the patient merely needs to breathe normally to introduce the medication into the airway. Thus, treatment can be delivered even to an unconscious patient or an infant. It is also considered an advantage of nebulizers that quantities of moisture are delivered to the airway; this may help to fluidize secretions and tends to increase patient comfort. The typical nebulized medication is a water-soluble substance which can form relatively dilute aqueous solutions. This is desired, due to the relatively large volumes of solution which will be entrained in an inhaled air stream, and to the very small quantities of drug which will typically be delivered in a single treatment. Handling of a drug solution is quite uncomplicated: a desired volume of a solution (usually aqueous) is either nebulized directly or is measured into a larger volume of sterile water for nebulization. However, some very useful inhalation drugs have little or essentially no water solubility. Examples of such drugs are corticosteroids, typically administered in the treatment of asthma by inhalation from pressurized metered dose inhalers, either in alcohol solution or as suspended micronized particles, or from dry powder inhalers of various types. It is also known to form an aqueous suspension of drug particles, for nebulization. Commercial products, which have not been made available in all countries, currently include beclomethasone dipropionate (sold by Glaxo under the trade name BECOTIDE) and budesonide (formulated with a citrate-citric acid buffer and Polysorbate 80 surfactant, and sold by Astra under the trade name PULMICORT). Corticosteroids have also been formulated in liposome suspensions in aqueous media, for nebulizer delivery, as in U.S. Pat. No. 5,192,528. The therapeutic advantages of the corticosteroid mometasone furoate for treating disorders of the lower airway make this drug a desirable candidate for delivery by nebulization. Since this drug is not soluble in aqueous media, it has become necessary to develop aqueous suspensions for nebulization. SUMMARY OF THE INVENTION The invention comprises an aqueous suspension of micronized mometasone furoate monohydrate, also containing a nonionic surfactant, a soluble salt and optionally a pH buffer. Preferred surfactants are those known as polysorbates. The soluble salt may be sodium chloride, in amounts needed to render the solution phase isotonic. When the buffer is present, it preferably will be chosen to maintain a solution pH between about 3 and about 7. BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a graphical representation of results from the experiment of Example 3. DETAILED DESCRIPTION OF THE INVENTION Percentages expressed herein are meant to indicate percent by weight, unless the context clearly dictates otherwise. The suspension formulations of the invention may be delivered to a patient using any of the usual nebulizer devices. Typical commercial nebulizer devices produce dispersions of droplets in gas streams by one of two methods. Jet nebulizers use a compressed air supply to draw up a fluid by venturi action and introduce it into a flowing gas stream, after which the fluid is caused to impact one or more stationary baffles to remove excessively large droplets. Ultrasonic nebulizers use an electrically driven transducer to subject a fluid to high-frequency oscillations, producing a cloud of droplets which can be entrained in a moving gas stream; these devices are less preferred for delivering suspensions. There are hand-held nebulizers which atomize the fluid with a squeeze bulb air supply, but the more widely used equipment incorporates an electrically powered compressor or connects to a cylinder of compressed gas. Although the various devices which are commercially available vary considerably in their delivery efficiency for a given medicament, they all are useful for the treatment of the present invention; it is necessary for the prescriber to specify an exact amount of medicament formulation which is to be charged to each particular device, since their respective outputs of respirable droplets are far from identical. Suspension formulations suitable for nebulization must, of course, contain solid particles of a respirable size (e.g., preferably averaging less than about 5 .mu.m in the largest dimension and more preferably averaging less than about 2 .mu.m) and must maintain their suspended particle size distribution during storage. In addition, the particle-containing droplets formed during nebulization of the formulations must have appropriate sizes for deposition in the desired area of the respiratory system. Since the formulations of the invention are to be inhaled, it is necessary that they be free of pathogenic organisms. Thus, they may be prepared and handled under sterile conditions, or may be sterilized before or after packaging. In addition, or in lieu of sterilization, a preservative may be incorporated to minimize the possibility of microbial contamination. In addition, all components of the formulations must be chosen for inhalation safety, as the treated tissues are quite sensitive to irritants; it is commonly known that many of the common preservatives have a considerable potential for causing irritation. The inventive formulations comprise water, mometasone furoate monohydrate, a nonionic surfactant, a soluble salt and optionally a pH buffer. Water for use in the formulations should meet or exceed the applicable regulatory requirements for use in inhaled drugs. Specifications established by the United States Pharmacopoeia for "Sterile Water for Injection" or "Sterile Water for Inhalation" are examples of water suitable for use to prepare formulations of the invention. Mometasone furoate is a corticosteroid having the chemical name 9.alpha.,21-Dichloro-11.beta.,17-dihydroxy-16.alpha.-methylpregna-1,4-dien e-3,20-dione 17-(2-furoate), and is currently marketed by Schering Corporation in cream and lotion formulations for the treatment of dermatologic conditions. Information concerning the preparation and properties of mometasone furoate is given in U.S. Pat. 4,472,393. This compound may be used to prepare mometasone furoate monohydrate for use in the present invention. Information concerning the preparation and properties of mometasone furoate monohydrate is given in PCT International Application WO 92/04365. In general, the concentration of mometasone furoate included in the suspension formulation will depend upon the dose to be delivered to the patient, ease of handling and the characteristics of the nebulizer equipment, as the devices vary considerably in their suspension capacities and nebulization efficiencies. Typical suspensions may contain as much as about 5 mg/mL of mometasone furoate, although lower concentrations, such as 50 .mu.g/mL to 1 mg/mL are more customary for most equipment. Surfactants are frequently categorized by their chemical nature, i.e., as cationic, anionic or nonionic. Cationic surfactants, such as cetyl pyridinium chloride, and anionic surfactants, such as docusate sodium, do not appear to provide proper dispersions of particles in the formulations. Many nonionic surfactants are suitable for maintaining the particulate suspensions of the invention. These include surfactants identified as "polysorbates" in the CTFA International Cosmetic Ingredient Dictionary; such surfactants are mixtures of fatty acid esters (predominately monoesters) of sorbitol and sorbitol anhydrides, condensed with ethylene oxide. Although these surfactants vary widely in their hydrophilic-lipophilic balance ("HLB") numbers, they all appear to function well in the invention. Commercially available polysorbates which are useful in the invention include those listed in the following table, which shows the CTFA designation (Polysorbate number), identity of the fatty acid used to produce the material and the number of moles of ethylene oxide reacted with each mole of ester. Compositions identified with an asterisk are predominately triesters. Polysorbate Acid Moles EtO 20 Lauric 20 21 Lauric 4 40 Palmitic 20 60 Stearic 20 61 Stearic 4 65* Stearic 20 80 Oleic 20 81 Oleic 5 85* Oleic 20 In general, Polysorbate surfactants will be present in a formulation at about 50 to 500 .mu.g/mL. When the surfactant concentration is below about 20 .mu.g/mL, the particles tend to form cakes which are not easily redispersed. Useful surfactants also include the "Poloxamers," which are block polymers of polyoxyethylene and polyoxypropylene, generally corresponding to the following formula: HO(CH.sub.2 CH.sub.2 O).sub.x [CH(CH.sub.3)CH.sub.2 O].sub.y (CH.sub.2 CH.sub.2 O).sub.z H Representative commercially available poloxamer surfactants are listed in the following table, wherein the CTFA designation (Poloxamer number) and average values of x, y and z are given. Poloxamer x y z 101 2 16 2 105 11 16 11 108 46 16 46 122 5 21 5 123 7 21 7 124 11 21 11 181 3 30 3 182 8 30 8 183 10 30 10 184 13 30 13 185 19 30 19 188 75 30 75 212 8 35 8 215 24 35 24 217 52 35 52 231 6 39 6 234 22 39 22 235 27 39 27 237 62 39 62 238 97 39 97 282 10 47 10 284 21 47 21 288 122 47 122 331 7 54 7 333 20 54 20 334 31 54 31 335 38 54 38 338 128 54 128 401 6 67 6 402 13 67 13 403 21 67 21 407 98 67 98 Poloxamer surfactants are used at concentrations similar to those for the Polysorbates, although certain members are useful at concentrations up to about 1 mg/mL. In general, the chosen surfactant should not materially increase the viscosity of the suspension formulation, since the efficiency of the nebulization process is particularly sensitive to viscosity. Many nonionic surfactants are useful for preparing inhalation and/or injectable drug formulations, and any of these should be suitable for use in the present invention. The formulations further include a soluble salt. This salt performs at least two functions: it minimizes the effects of the inhaled formulation on the normal cell fluid balance of airway cells and also stabilizes the suspension of medicament. For the first function, it is preferred to use sufficient salt concentrations to render the formulation isotonic; sodium chloride and potassium chloride are preferred for this purpose. It has been found that adequate suspension stability is produced by isotonic concentrations (i.e., about 0.9 weight percent) of sodium chloride, although concentrations about 0.2 to about 2 weight percent are useful. Any physiologically compatible alkali metal or alkaline earth metal soluble salt can be used in the present invention. Optionally, the formulations will contain a pH buffer, to maintain the formulation pH between about 3 and about 7. It has been found that stability of the drug (as measured by the absence of degradation reaction products) in suspension is improved by maintaining pH conditions below about 6. For reasons of tissue compatibility, excessively acidic products are not desired, so the pH should not be made to be below about 3. Some experimentation may be needed to qualify specific buffers for use in the invention: phosphate buffers in concentrations of 1 to 50 millimolar do not appear to adequately prevent caking of the particulates in the suspension when there is no added soluble salt. A citrate-citric acid buffer, maintaining pH between about 4 and about 5, has been used with particularly good effect for both maintaining pH during storage and preventing any particulate caking in the absence of soluble salts. The citrate-citric acid buffer may be present in suspension formulations at concentrations at least about 2 and up to about 50 millimolar. While the literature has some reports of cough being induced by such buffer systems, this seems to occur primarily at the 150-200 millimolar level, although one report attributed cough to only a 35 millimolar concentration. Sterility or adequate antimicrobial preservation of the final packaged formulation is needed for patient protection. The use of antimicrobial preservatives is less desirable, since certain of these have been associated with adverse clinical effects, such as bronchospasm. Alternative processes which may be considered for achieving sterility usually will not include sterilization steps for the micronized drug substance or formulation, since it has been found that the drug undergoes degradation under the influence of gamma-ray irradiation and sterilizing heat conditions. Sterilization by filtration ordinarily will not be feasible, due to the suspension nature of the formulation. Thus, it is preferred to produce the mometasone furoate monohydrate under sterile conditions, conduct the drug micronization in a sterile environment, and perform a sterile packaging operation. Methods are known for reducing particle sizes into the micrometer range, including mechanical milling, application of ultrasonic energy and other techniques. Mechanical milling frequently generates high surface temperatures on the particles, and this is undesirable for mometasone furoate monohydrate which tends to lose some part of its hydration under the influence of high temperatures. Ultrasonic techniques are quite slow in their action, generally requiring very long processing times, but are capable of producing acceptable suspensions. Suspensions of drug particles can rapidly undergo particulate size reduction when subjected to "jet milling" (high pressure particle in liquid milling) techniques. A presently preferred jet milling procedure for producing the formulations of the invention involves the use of the "Microfluidizer" system sold by Microfluidics International Corporation of Newton, Mass., U.S.A. This device divides a fluid stream, flowing under high pressures (up to about 40,000 pounds per square inch, or 2.76.times.10.sup.8 newton/meter.sup.2), between two separate microchannel paths and then recombines them from generally perpendicular directions to create very high shear, impact and cavitation forces. By continuously recirculating suspensions through the system for a predetermined time period, it is possible to reproducibly create desired distributions of micron- and submicron-sized particles. Since the particles are always completely surrounded by liquid, their surfaces will not develop high temperatures under the influence of the size reduction forces, and the hydration water in the drug crystals will remain intact. Other useful equipment which utilizes related technology is available from Avestin Inc., Ottawa, Ontario, Canada |
| PATENT EXAMPLES | Available on request |
| PATENT PHOTOCOPY | Available on request |
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