Inhaler propellants

General information

Pulmonary delivery of drugs is the administration route of choice in respiratory diseases such as chronic obstructive pulmonary disease and asthma. Different devices are available, including metered-dose inhalers, dry powder inhalers, and nebulizers, and nearly 80% of asthmatic patients worldwide use metered dose inhalers [ ]. Chlorofluorocarbons have been used as an aerosol propellant in metered-dose inhalers; however, they deplete the ozone layer and are being replaced by more environment-friendly propellants, even though the contribution of aerosols of this type to the total global burden of chlorofluorocarbons is less than 0.5%. The first chlorofluorocarbon-free metered-dose inhaler for asthma treatment was approved by the FDA in 1996 [ ] and the European Union set 2005 as a target date for the withdrawal of all chlorofluorocarbon-based inhalers [ ]. In the USA, prescriptions for chlorofluorocarbon-free medications rose from 16.4 million in 1996 to 33.8 million in 2000 [ ]. Most of the chlorofluorocarbon-free medications were steroids for nasal use (27.2 million). However, chlorofluorocarbon-containing medications still represented two-thirds of all prescriptions and increased from 63.0 to 67.6 million dispensed [ ].