Pirbuterol is a beta-adrenoceptor agonist which differs structurally from salbutamol in the substitution of a pyridine ring for the benzene ring. In common with salbutamol, pirbuterol demonstrates both bronchodilatory and cardiovascular effects. Generally, improvements of up to 25% are noted in forced expiratory volume in 1 second (FEV1) [versus baseline or placebo] in asthmatic patients treated with pirbuterol for several months. In individual 12-week double-blind comparative studies, pirbuterol aerosol appeared similar to orciprenaline (metaproterenol) aerosol, and orally administered pirbuterol appeared similar to orally administered salbutamol in bronchodilator efficacy. However, well-designed long term comparative studies are needed to more clearly define the comparative efficacy of pirbuterol and alternative beta-adrenoceptor agonists.