Effect of nifedipine on hyperreactive bronchial responses to methacholine.

Recent reports in the literature suggest that disorders in the regulation of calcium ion concentration in airway smooth muscle may be at the basis of bronchial hyperreactivity. In order to evaluate whether nifedipine, a calcium channel blocking drug, could alter the bronchial reactivity to methacholine, nine patients suffering from occupational asthma were submitted to bronchial challenge with methacholine with and without premedication with nifedipine, 20 mg sublingually. The bronchial responses were followed by measuring FEV1 by means of a bell spirometer. The provocation dose of methacholine capable to induce a 15% decrease of FEV1, (PD15FEV1) was considered the bronchial threshold dose for each subject. Average PD15FEV1 increased from 310.6 micrograms (SD = 191.7) in the test without premedication with nifedipine to 1,012.3 micrograms (SD = 640.0) in the test with premedication (P less than .01). Subjectively, all the patients showed better tolerance to the bronchoconstriction during the test with nifedipine. Our data indicate that nifedipine decreases bronchial reactivity to methacholine.