Terfenadine blockade of exercise-induced bronchospasm.

Terfenadine, in doses of 60, 120, and 180 mg, provided significant bronchodilation for up to four hours after administration. In addition, when the same doses were given four hours prior to exercise, the drug demonstrated significant blockade of exercise-induced bronchospasm at two and five minutes postexercise. These effects on exercise-induced bronchospasm followed a dose-response curve; 180 mg had the most significant effect. All dosing levels, however, produced both bronchodilation and a significant degree of blockade of exercise-induced bronchospasm. No patients were bothered by adverse effects during this single-dose study. Eight of the 11 subjects who completed the study also noted some improvement in their nasal congestion during the testing period when they were on the active drug.