Abstract

The value of giving drugs by inhalation in the treatment of asthma is well established. Delivery of a low dose of drug directly to the site of action reduces unwanted systemic effects, and enables bronchodilators to act at once. The most widely used delivery system, the metered dose inhaler (MDI), releases drug from a multi-dose pressurised canister using a chlorofluorocarbon (CFC) propellant (e.g. ‘Freon’). It is convenient but has several disadvantages in clinical use, and recognition of the damaging effect of CFCs on the ozone layer is increasing the demand for alternatives to CFC aerosols in asthma. A confusing array of newer drug delivery systems now exists. This article assesses their advantages and place in treatment.