title: Moisture transport into chlorofluorocarbon-free metered dose inhalers.
abstract: Moisture is known to affect the stability of some metered dose inhalers (MDIs). Hydrofluoroalkanes such as tetrafluoroethane (134a) and heptafluoropropane (227) are known to have higher affinity for moisture than the currently used chlorofluorocarbon propellents. An initial study was conducted to determine the water vapor transmission rates of various elastomers that may be used as gaskets in MDIs. A further study was conducted to measure the moisture ingress rates of various chlorofluorocarbon-free MDIs. The data indicate that moisture transport into chlorofluorocarbon-free MDIs is influenced by the elastomeric nature of the gaskets used and the type of hydrofluoroalkane formulation and storage conditions used.
authors.affiliation: R&D Laboratory, Valois Pharm, Le Vaudreuil, France.
authors.forename: G
authors.initials: G
authors.lastname: Williams
mesh_terms: D000335:Aerosol Propellants; D017402:Chlorofluorocarbons; D016503:Drug Delivery Systems; D020724:Elastomers / Q000737:chemistry; D009330:Nebulizers and Vaporizers; D013227:Steam / Q000032:analysis*
chemical_list: D000335:Aerosol Propellants; D017402:Chlorofluorocarbons; D020724:Elastomers; D013227:Steam