The effect of inhaled nifedipine on bronchial reactivity to histamine in man.

We have administered nifedipine by aerosol to six patients with mild asthma to determine whether local administration of a potent calcium channel blocker has any effect on resting airway tone or histamine reactivity. Subjects had their responsiveness to histamine measured and then received either nifedipine, 10 mg in 40% ethanol, or diluent alone in a randomized, double-blind fashion. Specific airway conductance, blood pressure, and heart rate did not change after either inhalation. Histamine reactivity was significantly reduced after the nifedipine aerosol, the geometric mean provocative concentration causing a 35% fall in specific airway conductance, rising from 5.0 to 10.9 mg/ml of histamine (p less than 0.05). In individuals this protective effect was variable but overall was no greater than that observed after sublingual nifedipine. Plasma nifedipine concentrations were measured in two subjects after administration of the aerosol and confirmed that inhaled nifedipine is absorbed across the bronchial mucosa.