Drug – bio-affecting and body treating compositions – Effervescent or pressurized fluid containing – Organic pressurized fluid
Patent
1993-03-17
1994-09-20
Page, Thurman K.
Drug, bio-affecting and body treating compositions
Effervescent or pressurized fluid containing
Organic pressurized fluid
424 43, 424 46, 424489, 424490, 424498, 427 214, 514951, 514975, A61K 912, A61K 972
Patent
active
053487303
DESCRIPTION:
BRIEF SUMMARY
This invention relates to medicinal aerosol formulations and in particular to formulations suitable for pulmonary, nasal, buccal or topical administration which are at least substantially free of chlorofluorocarbons.
Since the metered dose pressurized inhaler was introduced in the mid 1950's, inhalation has become the most widely used route for delivering bronchodilator drugs and steroids to the airways of asthmatic patients. Compared with oral administration of bronchodilators, inhalation offers a rapid onset of action and a low instance of systemic side effects. More recently, inhalation from a pressurized inhaler has been a route selected for the administration of other drugs, e.g., ergotamine, which are not primarily concerned with the treatment of a bronchial malady.
The metered dose inhaler is dependent upon the propulsive force of a propellant system used in its manufacture. The propellant generally comprises a mixture of liquified chlorofluorocarbons (CFC's) which are selected to provide both the desired vapour pressure and stability of formulation. Propellants 11, 12 and 114 are the most widely used propellants in aerosol formulations for inhalation administration.
In recent years it has been established that CFC's react with the ozone layer around the earth and contribute towards its depletion. There has been considerable pressure around the world to reduce substantially the use of CFC's, and various Governments have banned the "non-essential" use of CFC's. Such "non-essential" uses include the use of CFC's as refrigerants and blowing agents, but heretofore the use of CFC's in medicines, which contributes to less than 1% of the total use of CFC's, has not been restricted. Nevertheless, in view of the adverse effect of CFC's on the ozone layer it is desirable to seek alternative propellant systems which are suitable for use in inhalation aerosols.
Our copending European Patent Application No. 89312270.5 discloses an aerosol formulation comprising a medicament, a surfactant, 1,1,1,2-tetrafluoroethane and at least one compound having a higher polarity than 1,1,1,2-tetrafluoroethane.
It is disclosed that 1,1,1,2-tetrafluoroethane, hereinafter referred to as Propellant 134a, may be employed as a propellant for aerosol formulations suitable for inhalation therapy when used in combination with a compound having a higher polarity than Propellant 134a. Suitable compounds include alcohols such as ethyl alcohol, isopropyl alcohol, propylene glycol, hydrocarbons such as propane, butane, isobutane, pentane, isopentane, neopentane, and other propellants such as those commonly referred to as Propellants 11, 12, 114, 113, 22, 142b , 152a, 124 and dimethyl ether. The combination of one or more of such compounds with Propellant 134a provides a propellant system which has comparable properties to those of propellant systems based on CFC's, allowing use of known surfactants and additives in the pharmaceutical formulations and conventional valve components. This is particularly advantageous since the toxicity and use of such compounds in metered dose inhalers for drug delivery to the human respiratory tract is well established.
Non-perfluorinated surfactants have commonly been used as dispersing agents for powdered medicaments in aerosol propellants in which the non-perfluorinated surfactants are soluble. Examples of such aerosol formulations are disclosed in British Patents Nos. 837465, 977934, 1063512, 2001334 and US Pat. No. 4,352,789. However, many of these non-perfluorinated surfactants are substantially insoluble in Propellant 134a and other propellants which are being considered as replacements for chlorofluorocarbon aerosol propellants i.e., a ordinary room temperature it requires more than 10,000 parts of propellant to dissolve 1 part of surfactant.
It has been found that non-perfluorinated surfactants which are insoluble in a propellant may nevertheless be used with such a propellant to form stable dispersions of powdered medicament provided the powdered medicament is pre-coated with the non-perfluorinated
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Greenleaf David J.
Jinks Philip A.
Purewal Tarlochan S.
Griswold Gary L.
Harrison Robert H.
Kirn Walter N.
Minnesota Mining and Manufacturing Company
Page Thurman K.
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