Comparative modification of antigen-induced bronchoconstriction by the calcium antagonists, nifedipine and verapamil

We compared the effects of the two calcium antagonists, nifedipine and verapamil, on baseline airway function and antigen-induced bronchoconstriction in asymptomatic subjects with ragweed hypersensitivity and a history of bronchial asthma. Twelve subjects received a single oral dose of 20 mg of nifedipine or 160 mg of verapamil before inhalation with ragweed antigen. Mean specific airway conductance, a measurement of airway obstruction, was not affected by either agent; nifedipine caused bronchodilatation in two subjects, and verapamil was followed by slight bronchoconstriction in another subject. Nifedipine partially or completely blocked the antigen-induced bronchoconstriction in 67 percent (8/12) of the subjects (p less than 0.05). Two of the subjects who were protected by nifedipine were also protected by pretreatment with verapamil, while this drug was without effect in the others. This study demonstrates that both nifedipine and verapamil in a single oral dose may attenuate antigen-induced bronchoconstriction in some subjects with allergic bronchial asthma and that nifedipine may be more effective than verapamil.