Nifedipine in the prevention of asthma induced by exercise and histamine

Eight young men with documented exercise-induced asthma each performed two standard exercise tests and underwent two histamine challenges on separate days after double blind administration of either 20 mg nifedipine or placebo. The response to exercise was assessed by the maximal fall in forced expiratory volume in one second (FEV1) and to inhaled histamine by calculating the dose that produced a 20% fall in FEV1 (PC20). After premedication with nifedipine, the severity of exercise-induced asthma was significantly reduced (mean percent fall in FEV1, 6%, compared with 24% after placebo) and reactivity to histamine was reduced (geometric mean PC20, 1.68 mg X ml-1, compared with 0.46 mg X ml-1 after placebo). These results imply that nifedipine has a direct action on bronchial smooth muscle contractility but they do not exclude an additional effect on the secretion of chemical mediators from mast cells.