Lack of dose-response effect of terfenadine on resting bronchomotor tone in patients with asthma.

Bronchodilatation data from three, four-period cross-over studies were combined to assess the effect of oral terfenadine 60, 120, 180 mg and placebo on the airways of 26 patients with atopic asthma. Meta-analysis of these data showed that mean changes in FEV1 from pre-dose to 4 hr were 11.4, 14.6 and 11.8% for the three doses of terfenadine, respectively, and -2.9% for placebo. There was a significant treatment effect (P = 0.0001) but no effect of dose. Terfenadine, a non-sedating histamine H1-receptor antagonist, caused bronchodilatation in a single dose. Whether this effect is sustained with long-term treatment requires further investigation.