Drug – bio-affecting and body treating compositions – Effervescent or pressurized fluid containing – Organic pressurized fluid
Patent
1986-11-10
1989-03-21
Foelak, Morton
Drug, bio-affecting and body treating compositions
Effervescent or pressurized fluid containing
Organic pressurized fluid
514 78, 514 95, 514 99, 514149, 514183, 514255, 514315, 514506, 514558, 514740, 514743, 514762, 514767, 514786, 514937, A61K 3100
Patent
active
048141615
DESCRIPTION:
BRIEF SUMMARY
This invention relates to medicinal aerosol formulations and in particular to drug-containing chlorofluorocarbon aerosol propellent formulations for topical or for endopulmonary or nasal inhalation administration.
Medicinal aerosol formulations generally contain a mixture of chlorofluorocarbons, e.g. trichloromonofluoromethane (Propellent 11), dichlorotetrafluoroethane (Propellent 114) and dichlorodifluoromethane (Propellent 12). The drug is either present as a solution in the aerosol formulation or as a dispersion of fine particles. For endopulmonary or nasal inhalation, particles predominantly in the size range 2 to 5 microns are required.
There are very few drugs which can be solubilised in chlorofluorocarbon aerosol propellents alone. Generally, it is necessary to utilise a polar co-solvent, such as ethanol, in order to achieve solubilisation of the drug. However, the resulting solutions can be chemically unstable due to reaction between the co-solvent and the drug or the co-solvent and the propellent system.
Furthermore, when large proportions of co-solvent, e.g. ethanol, are required to achieve dissolution of the drug, the resulting spray droplet size may be too large for certain applications, in particular, endopulmonary inhalation therapy.
Suspension of drug in aerosol propellents is achieved by pulverising the drug into the desired particle size range and thereafter suspending the particles in propellents with the aid of a surfactant. The disadvantages of this technique are that drug particles may agglomerate, grow in size or become adsorbed onto the surface of the container in which the formulations are stored prior to dispensing. Furthermore, it is necessary to agitate the product prior to use in order to ensure dispersion of the formulation and uniformity of dosage.
The present invention provides an alternative technique for incorporating drugs into chlorofluorocarbon aerosol propellents.
Therefore according to the invention there is provided an aerosol formulation comprising one or more chlorofluorocarbon aerosol propellents, a glycerol phosphatide and a drug, the drug being dissolved in the composition.
The glycerol phosphatide may be any one of the following compounds; phosphatidylcholine (lecithin), phosphatidylethanolamine (cephalin), phosphatidylinositol, phosphatidylserine, diphosphatidylglycerol or phosphatidic acid.
Surprisingly it has been found that glycerol phosphatides cause complete dissolution of certain drugs in chlorofluorocarbon propellents. Phosphatidylcholine (lecithin) has been utilised as a surfactant in aerosol formulations containing suspended drug particles but heretofore it has not been appreciated that this particular compound can enhance the solubility of certain drugs in chlorofluorocarbon propellents.
It has been found that drugs having at least very slight solubility in chlorofluorocarbon propellents will exhibit an enhanced solubility in the chlorofluorocarbon propellent in the presence of glycerol phosphatide. It is postulated that this enhanced solubility is attributable to drug in true solution becoming associated with reverse micelles of the glycerol phosphatide which allows further drug to dissolve in the propellent. Thus, the solubilisation process is believed to be as follows: ##STR1## Whilst the compositions of the invention appear visibly to be true solutions since there is no dispersed phase apparent, they are more correctly micellar solutions.
The formulations of the invention may be prepared by forming a concentrate of glycerol phosphatide with a drug and Propellent 11. The concentrate may be formed by simple admixture with agitation and optionally under heating, e.g. 50.degree. C., until complete dissolution of the drug has been attained. The concentrate may then be mixed with the remainder of the propellent formulation, e.g. Propellents 12 and 114.
Phosphatidylcholine is the most suitable glycerol phosphatide to use in view of its low toxicity and high drug solubilising efficacy. Phosphatidylcholine purified from soya bean lecithin is readily availa
REFERENCES:
patent: 4310526 (1982-01-01), Doria et al.
patent: 4380534 (1983-04-01), Fukui et al.
patent: 4419352 (1983-12-01), Cox et al.
Bell Alexander
Fischer Franz X.
Jinks Philip A.
Acquah S. A.
Foelak Morton
Kirn Walter N.
Riker Laboratories Inc.
Sell Donald M.
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