ABC of asthma; Methods of delivering drugs

This article is adapted from the 5th edition of the ABC of Asthma in Adults, which will be published at the end of the year and will be available from www.hammicksbma.com

Various inhaler devices and formulations have been developed to deliver drugs efficiently, minimise side effects, and simplify use. With the range of devices available nearly all patients can take drugs by inhalation. All the available devices used appropriately can provide adequate drug to the airways. Inhalers should not be prescribed without checking that the patient can use the device satisfac torily. This should be rechecked on subsequent visits as errors can develop and interfere with treatment. Some drugs, such as leukotriene receptor antagonists and theophylline, cannot be given by inhalation.

Inhalers deliver the drug directly to the airways. Even when a metered dose inhaler is used properly, however, only about 10% of the drug reaches the airways below the