Effect of an oral H1-receptor antagonist, terfenadine, on antigen-induced asthma

We have investigated the effect of a specific H1-receptor antagonist, terfenadine, on antigen-induced asthma. In a double-blind, randomized fashion, nine stable asthmatics were given placebo, or terfenadine 60, 120 or 180 mg orally, 12 and 4 hours before challenge. Cumulative bronchial challenge with specific antigen aerosols were delivered from a nebulizer attached to a breath-actuated dosimeter. Response was monitored by specific airway conductance and measurements from partial expiratory flow-volume curves, performed in a body plethysmograph, on line to a computer. Initially the histamine dose-response curves of four subjects were found to be shifted 10-fold to the right by terfenadine 60 mg, given orally. Compared with placebo, terfenadine 60 mg, given orally. Compared with placebo, terfenadine significantly shifted the mean antigen dose-response curves of all measurements to the right. However, this shift was small and not correlated to the dose of terfenadine. There was marked intersubject variation in the effect. Terfenadine produced no side effects. The immediate bronchial response to antigen can be attenuated by an oral H1-receptor antagonist, but the effect is small and, in general, unlikely to be clinically useful.