Effect of terfenadine on cold air-induced bronchospasm

Cold air hyperventilation challenge (CAHC) has been shown to induce bronchoconstriction in asthmatics. We investigated whether terfenadine, a non-sedating H₁ antihistamine, had a protective effect against CAHC. Twelve mild-moderate asthmatics, sensitive to both methacholine and CAHC, underwent a double-blind 3-way crossover study of terfenadine at doses of 0, 120, and 240 mg. For four hours after administration of the study drug, pulmonary responses were measured, followed by a CAHC. There was a significant improvement in pulmonary function on the 120-mg and 240-mg days. The percent drop in FEV₁ to CAHC was determined by comparing the pre-challenge baseline to the challenge responses. There was a significant attenuation in the FEV₁ fall immediately after challenge on active drug days, but it was not sustained. Terfenadine appears to have an attenuating effect against CAHC-induced bronchoconstriction.