Mizolastine: antihistaminic activity from preclinical data to clinical evaluation

Mizolastine, a new H1-receptor antagonist, is highly selective for histamine H1 receptors and has no anticholinergic, antiadrenergic, or antiserotonin activity. It is rapidly absorbed after oral ingestion, with peak plasma concentrations occurring at 1.5 h. The distribution and terminal elimination half-life values are 2 and 13 h, respectively, in healthy young adult volunteers. Half-life values are longer in the elderly and in subjects with chronic renal insufficiency; however, the differences are not large enough to be clinically relevant or to necessitate a dose adjustment in these populations. Mizolastine produces prompt, sustained, peripheral blockade of histamine H1 receptors in the skin. Suppression of the histamine-induced wheal and flare begins 40-60 min after ingestion of a 10-mg dose, peaks at 3-4 h, lasts for at least 24 h, and does not decrease during regular once-daily dosing. The amount of wheal suppression is comparable to that produced by other leading new H1-receptor antagonists. These pharmacokinetic and pharmacodynamic studies of mizolastine provide its clinical pharmacology 'signature'. They also provide the scientific rationale for recommending a once-daily 10-mg dose and suggest that the efficacy and effectiveness of mizolastine will be widely confirmed in allergic disorders, especially rhinitis and urticaria.