[Changes in metered dose inhaler propellants].

The understanding of the damaging effect of chlorofluorocarbons (CFCs) on the stratospheric ozone has led to international agreements calling for the total phase-out of CFC production. The banning of CFCs in pressurized metered dose inhalers used in airways disorders has been postponed on a temporary basis until replacement propellants have been identified. Hydrofluoroalkanes HFA-134a and HFA-227 have been shown to have no ozone damaging potential and to be safe. However, HFAs cannot simply be substituted for CFCs in inhalers of identical design. Their use has required changes in many aspects of the drug formulation, inhaler design and manufacture. This, in turn, has provided at least to some pharmaceutical companies an opportunity to assess and enhance the performances of new inhalers. The new products are neither technically nor pharmacologically identical to their CFC-based counterparts. Some of them have now completed clinical trials and the transition has already started: by the end of 1998, 2 short acting beta-agonist HFA-based inhalers and a corticosteroid HFA-based inhaler have reached the marketplace in France.