ABSTRACT

Bronchial asthma is characterised by wide variations over short periods of time in the resistance to flow in intrapulmonary airways (Sears, 1991; Lenfant eta!., 1992). The disease is therefore commonly treated with bronchodilators, notably {32adrenoceptor agonists, which relax the smooth muscle of the constricted airways. Expert opinion on the therapy of asthma has, however, undergone a transformation in recent years, with emphasis now being placed upon the early use of antiinflammatory or anti-allergic drugs, except in the mildest manifestations of the disease (Lenfant eta!., 1992). The bronchodilators still have a role, but in the opinion of some experts, {32-adrenoceptor agonist bronchodilators should only be used for the relief of asthniil: symptoms and not prophylactically (Anon, 1993; Page, 1993).