Orally administered nifedipine in chronic stable asthma. Comparison with an orally administered sympathomimetic

Calcium channel blockers have been shown to attenuate bronchoconstriction when given prior to bronchoprovocation challenge testing. However, they have not been found to induce bronchodilation when administered to asthmatic subjects with normal baseline lung function. In vitro data, on the other hand, suggest that preconstricted tracheal strips can be made to relax by the addition of calcium channel blockers. Therefore, we compared the effects of orally administered nifedipine (20 mg), albuterol (4 mg), and placebo on airway function in 10 asthmatic subjects with chronic stable asthma and baseline bronchoconstriction in a double-blinded, randomized, cross-over trial. Nifedipine caused a significant increase in FEV1 (0.21 +/- 0.08 SEM L) at 40 min after administration of the drug. The mean of the change in FEV1 throughout the 2-h observation period after nifedipine (0.19 +/- 0.08 L) was significant when compared with baseline (p less than 0.05) and placebo control values (p less than 0.005) but tended to be less than the bronchodilation observed after albuterol. Only 3 subjects had an increase in FEV1 greater than 10% of their baseline value after nifedipine compared with 7 subjects after albuterol and 2 subjects after placebo. These results are at least consistent with the hypothesis of a direct action of calcium channel blockers on bronchial smooth muscle and indicate that orally administered nifedipine has a weak bronchodilating effect in subjects with chronic stable asthma who have abnormal lung function.