Comparison of terfenadine once daily with terfenadine twice daily for the treatment of perennial allergic rhinitis.

In a double-blind, parallel-group study to compare the efficacy of 120 mg terfenadine taken orally once daily with that of the conventional regimen of 60 mg terfenadine taken twice daily, 30 patients with perennial allergic rhinitis were enrolled. Groups of 15 patients were treated for 7 days with either 60 mg terfenadine twice daily, morning and evening, or 120 mg terfenadine once daily in the morning and placebo in the evening. The physician detected marked to total relief of symptoms (sneezing, rhinorrhoea, nasal pruritus and nasal obstruction) at similar rates (60% and 66%) in the two groups and patients in both groups reported a reduction in symptoms. The incidence of reported side-effects (sedation and mild headache) was low and not significantly different using either regimen. The results indicate that the new once-daily regimen of terfenadine was as effective and as well tolerated as the twice-daily regimen for the treatment of perennial allergic rhinitis.