Transition to CFC-free metered dose inhalers--into the new millennium

Int J Pharm. 2000 May 15;201(1):89-107. doi: 10.1016/s0378-5173(00)00401-4.


Metered dose inhalers (MDIs) are the most popular vehicle for drug delivery into the lungs and some 500 million are manufactured each year. All MDIs marketed prior to 1995 contained chlorofluorocarbons (CFC) as a propellant. These are implicated in the depletion of stratospheric ozone and, except for specific exemptions, their production has been banned since 1996 under the terms of the Montreal Protocol. Hydrofluoroalkanes have been identified as suitable alternatives for MDI propellants but their physico-chemical properties differ significantly from CFCs and an extensive redevelopment and testing programme has been required to demonstrate the safety, quality and efficacy of HFA containing MDIs. Hydrofluoroalkanes contribute to global warming but the benefit to human health through continued MDI availability currently outweighs the environmental concern. Several HFA-MDIs have reached the market and the transition to replace existing CFC-MDIs is now underway.

Publication types

  • Review

MeSH terms

  • Aerosol Propellants*
  • Chlorofluorocarbons, Methane*
  • Humans
  • Nebulizers and Vaporizers / trends*


  • Aerosol Propellants
  • Chlorofluorocarbons, Methane