Comparative activity of cetirizine and mizolastine on histamine-induced skin wheal and flare responses at 24 h.

OBJECTIVE

The aim of our study was to compare the activity of cetirizine 10 mg with that of mizolastine 10 mg vs placebo at 24 h after intake in healthy volunteers.

METHODS

This was a double-blind, randomized, placebo controlled, three-way cross-over study with a wash-out period of 7 +/- 2 days between each period. The study included 36 healthy volunteers (18--50 years, mean age = 32 years; 9 males). The objective measurement was the cutaneous reactivity to increasing concentrations of histamine (0, 5, 10, 20, 40, 80, 160 mg ml(-1)) administered by prick tests. The reactivity was evaluated by the wheal and flare areas (mm2). The AUC (area under curves) values of the wheal and flare areas as a function of the log2 transformed histamine concentration were calculated for each subject and treatment, and compared.

RESULTS

A highly significant treatment effect was evidenced both for wheal and flare responses (P = 0.0001). This indicates the good activity of both cetirizine 10 mg and mizolastine 10 mg in inhibiting skin wheal and flare reactions to histamine. In addition, the mean AUC values significantly differed between cetirizine and mizolastine (64.8 and 117.8 log2 (mg ml(-1)) x mm2 for wheal, and 939.4 and 2340.8 for flare, respectively; P = 0.0001), with a superior activity of cetirizine than mizolastine at 24 h after intake both on wheal and flare responses. The tolerance of cetirizine and mizolastine was good. The severity of the adverse events was never more than 'moderate', 'fatigue' being the most frequent reported symptom [cetirizine (6 subjects), placebo (3), mizolastine (5)], followed by 'somnolence' [cetirizine (0), placebo (1), mizolastine (3)]. There was no serious adverse event.

CONCLUSIONS

This study shows that cetirizine (10 mg) suppresses skin reactivity to histamine more effectively than mizolastine (10 mg) 24 h after intake in healthy volunteers.