Acrivastine in seasonal allergic rhinitis: two randomized crossover studies to evaluate efficacy and safety.

In two randomized crossover studies, the antihistamine, acrivastine, was evaluated for the treatment of seasonal allergic rhinitis. One study on 31 patients found both 4 and 8 mg acrivastine given three times daily to be significantly better than placebo for alleviating hay fever. There were no significant differences in symptom scores between the two doses, although more patients (63%) favoured 8 mg acrivastine over the 4 mg dose (46%) or placebo (35%). The other study found the higher dosage regimen to be similar in efficacy to 1 mg clemastine given three times daily. Both dosages were significantly better than placebo for reducing symptom scores in all 18 evaluable patients. The incidence of adverse experiences was low in both studies; there being no dose-related effects of acrivastine. In the second study, drowsiness, probably or possibly treatment related, occurred on seven occasions during clemastine treatment and once with acrivastine. These studies indicate that 8 mg acrivastine given three times daily is both well tolerated and of equal efficacy to clemastine for the treatment of seasonal allergic rhinitis.