Drug – bio-affecting and body treating compositions – Effervescent or pressurized fluid containing – Organic pressurized fluid
Reexamination Certificate
1995-05-31
2004-06-01
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Effervescent or pressurized fluid containing
Organic pressurized fluid
C424S043000
Reexamination Certificate
active
06743413
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to pharmaceutical aerosol formulations. In another aspect this invention relates to pharmaceutical suspension aerosol formulations wherein the propellant comprises HFC 134a or HFC 227. In another aspect, it relates to pharmaceutical suspension aerosol formulations containing pirbuterol. In another aspect, it relates to pharmaceutical suspension aerosol formulations containing albuterol sulfate.
2. Description of the Related Art
Pharmaceutical suspension aerosol formulations currently use a mixture of liquid chlorofluorocarbons as the propellant. Fluorotrichloromethane, dichlorodifluoromethane and dichlorotetrafluoroethane are the most commonly used propellants in aerosol formulations for administration by inhalation.
Chlorofluorocarbons (CFCs), however, have been implicated in the destruction of the ozone layer and their production is being phased out.
Hydrofluorocarbon 134a (HFC 134a, 1,1,1,2-tetrafluoroethane) and hydrofluorocarbon 227 (HFC 227, 1,1,1,2,3,3,3-heptafluoropropane) are viewed as being more ozone friendly than many chlorofluorocarbon propellants; furthermore, they have low toxicity and vapor pressures suitable for use in aerosols.
Patent Applications WO 91/11495 and WO 91/11496 (both by Weil) describe pharmaceutical suspension aerosol formulations comprising a medicinal agent, optionally a surfactant, and a propellant mixture containing 1,1,1,2,3,3,3-heptafluoropropane and one or more additional components, e.g., pentane, butane, propellant 134a, propellant 11, propellant 125, or propellant 152a.
European Patent Office Publication 0 384 371 (Heiskel) describes solution aerosols in which 1,1,1,2,3,3,3-heptafluoropropane or its mixture with propane, butane, isobutane, dimethyl ether, or 1,1-difluoroethane serves as the propellant. The application does not, however, disclose suspension aerosols or pharmaceutical aerosol formulations.
European Patent Application 89.312270.5 (Purewal et al.) discloses, inter alia, aerosol formulations comprising a medicament, 1,1,1,2-tetrafluoroethane, a surface active agent, and at least one compound having higher polarity than 1,1,1,2-tetrafluoroethane.
U.S. Pat. No. 2,868,691 (Porush et al.) discloses aerosol formulations comprising a medicament, a halogenated lower alkane propellant, and a cosolvent which assists in dissolving the medicament in the propellant. The chemical formula for the propellant given in Col. 2, lines 6-16, generically embraces HFC 134a and HFC 227. Examples of cosolvents disclosed include ethanol and diethyl ether.
U.S. Pat. No. 3,014,844 (Thiel et al.) discloses aerosol formulations comprising a micronized medicament, a halogenated lower alkane propellant and a surface-active agent to assist in the suspension of the medicament in the propellant. The chemical formula for the propellant given in Col. 4, lines 17-28, generically embraces HFC 134a and HFC 227.
Patent Application WO 90/01454 (Greenleaf et al.) discloses aerosol compositions having HFC 134a as the propellant and comprising a medicament coated with a non-perfluorinated surface active dispersing agent. This application describes control formulations containing only HFC 134a and 0.866 percent by weight of a drug.
Albuterol sulfate is a relatively selective beta-2 adrenergic bronchodilator. It is available in a variety of dosage forms including tablets, syrups and formulations suitable for inhalation. For example, VENTOLIN™ Inhalation Aerosol (commercially available from Allen & Hansburys) is a metered dose aerosol unit containing a microcrystalline suspension of albuterol (free base) in propellant (a mixture of trichloromonofluoromethane and dichlorodifluoromethane) with oleic acid. VENTOLIN ROTOCAPS™ for Inhalation (commercially available from Allen & Hansburys) contain a mixture of microfine albuterol sulfate with lactose and are intended for use with a specially designed device for inhaling powder. VENTOLIN™ Solution for Inhalation (commercially available from Allen & Hansburys) is an aqueous solution of albuterol sulfate intended for use with a nebulizer.
Pirbuterol acetate is a relatively selective beta-2 adrenergic bronchodilator. MAXAIR™ Inhaler (commercially available from 3M Pharmaceuticals, St. Paul, Minn) is a metered dose aerosol unit containing a fine-particle suspension of pirbuterol acetate in the propellant mixture of trichloromonofluoromethane and dichlorodifluoromethane, with sorbitan trioleate.
SUMMARY OF THE INVENTION
This invention provides a pharmaceutical suspension formulation suitable for aerosol administration, consisting essentially of a therapeutically effective amount of a drug and a propellant selected from the group consisting of HFC 134a, HFC 227, and a mixture thereof, said formulation being further characterized in that it exhibits substantially no growth in particle size or change in crystal morphology of the drug over a prolonged period, is substantially and readily redispersible, and upon redispersion does not flocculate so quickly as to prevent reproducible dosing of the drug.
This invention also provides an aerosol canister containing a formulation as described above in an amount sufficient to provide a plurality of therapeutically effective doses of the drug. Also provided is a method of preparing a formulation as described above, comprising the steps of: (i) combining an amount of the drug sufficient to provide a plurality of therapeutically effective doses and a propellant selected from the group consisting of HFC 134a, HFC 227, and a mixture thereof, in an amount sufficient to propel from an aerosol canister a plurality of therapeutically effective doses of the drug; and (ii) dispersing the drug in the propellant. This invention further provides a method of treating a mammal having a condition capable of treatment by inhalation, comprising the step of administering by inhalation a formulation as described above to the mammal.
In another aspect, this invention provides suspension aerosol formulations comprising a therapeutically effective amount of micronized albuterol sulfate and HFC 227 as substantially the only propellant. This invention also provides suspension aerosol formulations comprising a therapeutically effective amount of micronized albuterol sulfate, from about 0.1 to about 15 percent by weight of ethanol, and HFC 227 as substantially the only propellant. This invention also provides suspension aerosol formulations comprising a therapeutically effective amount of micronized albuterol sulfate, from about 5 to 15 percent by weight of ethanol, from about 0.05 to about 0.5 percent by weight of a surfactant selected from the group consisting of oleic acid and sorbitan trioleate, and HFC 227 as substantially the only propellant.
In another aspect this invention provides suspension aerosol formulations comprising a therapeutically effective amount of micronized pirbuterol acetate and a propellant comprising HFC 227, the formulation being further characterized in that it is substantially free of perfluorinated surfactant. This invention also provides suspension aerosol formulations comprising a therapeutically effective amount of micronized pirbuterol acetate, about 0.1 to about 12 percent by weight of ethanol, and a propellant comprising HFC 227. This invention also provides suspension aerosol formulations comprising a therapeutically effective amount of micronized pirbuterol acetate, about 5 to about 12 percent by weight of ethanol, about 0.05 to about 0.5 percent by weight of oleic acid, and a propellant comprising HFC 227.
This invention also provides a method for inducing bronchodilation in a mammal, comprising administering to the mammal a formulation as described above by inhalation.
DETAILED DESCRIPTION OF THE INVENTION
The term “suspension aerosol formulation” as used herein refers to a formulation in which the drug is in particulate form and is substantially insoluble in the propellant.
Amounts expressed herein in terms of percent refer to percent by weight based on the total weight of the formulation.
The formulatio
Jinks Philip A.
Moris Robert A.
Oliver Martin J.
Schultz David W.
Schultz Robert K.
3-M Company
Page Thurman K.
Sheikh Humera N.
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