Effects of azatadine, terfenadine, and astemizole on allergen-induced nasal provocation.

Fifty-six patients with ragweed seasonal rhinitis were challenged intranasally with ragweed. A clinical score (0-12)--including measurements of rhinomanometry, secretions, and sneezes--was generated. Each patient then received either azatadine (A), terfenadine (T), astemizole (AS), or nothing (control), for 1 week. Repeat challenges revealed changes in clinical score with A 3.6 (P less than .01), AS 3.1 (P less than .02), and T 2.7 (P less than .05). All three antihistamines similarly inhibited the nasal provocation response to ragweed.