Can an antihistamine delay appearance of hay fever symptoms when given prior to pollen season?

Abstract

Mizolastine is a new, nonsedating antihistamine providing satisfactory symptom relief in allergic conditions. The purpose of this study was to determine whether the onset of hay fever symptoms could be delayed in patients known to suffer seasonal allergic rhinoconjunctivitis symptoms if mizolastine was given before the pollen season. This double-blind study involved 342 patients, randomly allocated to once-daily 10 mg mizolastine (n = 115), once-daily 120 mg terfenadine (n = 116), or placebo (n = 111) groups. All patients started treatment on 1 May, before the onset of the grass pollen season. The prophylactic effect of test drugs was assessed on their ability to delay the time to the first hay fever crisis of the season, which was defined by the occurrence of one of the following events: use of rescue medication, study withdrawal because of treatment failure, or total diary symptom score over 18. Active treatments prolonged the time to the first crisis by approximately 1 week (mizolastine 55 days, terfenadine 57 days) in comparison with placebo (50 days) (survival curve analysis: Logrank test, P = 0.01; Wilcoxon test, P = 0.03). Tolerability was satisfactory and comparable between groups. Thus, mizolastine can be safely used to delay and to treat symptoms of seasonal allergic rhinitis.