DRUG-INDUCED ASTHMA - IMMUNOLOGICAL MECHANISMS AND PRACTICAL IMPLICATIONS

Bronchospasm can be elicited by a number of drugs, including widely used agents such as nonsteroidal anti-inflammatory drugs, beta-adrenergic blockers, opiates and radiographic contrast media. The postulated mechanisms of asthma induced by nonsteroidal anti-inflammatory drugs include altered sensitivity to leukotrienes and abnormal release of cytotoxic compounds from platelets. Although the precise mechanism of beta-adrenergic blocker-induced bronchospasm is not completely understood, multiple factors can influence individual patients. Contrast media induce release of mediators from mast cells without the need for preformed IgE antibodies. Other agents that infrequently cause asthma include anaesthetic agents and muscle relaxants. Although angiotensin converting enzyme inhibitors frequently provoke cough, they do not appear to aggravate asthma. Alternative therapeutic options are available for management of all of these individual categories of drug-induced asthma. Paradoxical.exacerbations of asthma have been associated with antiasthmatic medications such as intravenous hydrocortisone, aminophylline and inhaled sodium cromoglycate (cromolyn sodium). There is increasing concern that frequent use of beta-agonist metered dose inhalers may have deleterious effects in patients with asthma, and guidelines for their use are evolving. A wide variety of prescribed and over-the-counter medications can aggravate asthma. It is imperative for the physician to remind patients to bring or list for review all the pharmacological agents they are taking.