Multicenter, double-blind, placebo-controlled trial of terfenadine in seasonal allergic rhinitis and conjunctivitis.

A multiclinic, double-blind, parallel and controlled study was conducted in the 1982 spring pollen season to evaluate and compare the effects of terfenadine, 60 mg bid with those of chlorpheniramine 4 mg tid and placebo for a treatment period of seven days in patients with seasonal allergic rhinitis and conjunctivitis. Of a total of 397 patients enrolled in the seven study centers, 345 patients were accepted for evaluation of efficacy and 393 patients for safety. The results show that based on the physicians' assessment of the overall efficacy, terfenadine was significantly superior to placebo and comparable to chlorpheniramine in the relief of allergic symptoms, with moderate to complete relief being observed in 60% (68/113) of the terfenadine-treated patients, in 60% (71/119) of the chlorpheniramine-treated patients, and in 30% (34/119) of the placebo-treated patients. The daily evaluation of severity of symptoms by the patients show that the effect of terfenadine and chlorpheniramine was evident on the first day after entry, reached a peak on the second day after entry, and persisted thereafter. Side effects were minor and infrequent in all treatment groups. There was no statistically significant difference in the incidence of sedation between the terfenadine (7.6%) and placebo (2.4%) groups whereas the incidence of sedation with chlorpheniramine (19%) was significantly higher. In conclusion, terfenadine is as effective as chlorpheniramine in the treatment of symptoms of seasonal allergic rhinitis and conjunctivitis with an incidence of sedation not significantly different from that with placebo and significantly less than with chlorpheniramine.