Cetirizine: A New, Nonsedating Antihistamine

OBJECTIVE: To introduce cetirizine, a nonsedating antihistamine, and discuss its mechanism of action, chemistry, clinical and comparative trials, and adverse effects. DATA SOURCES: An English-language literature search of MEDLINE was conducted. STUDY SELECTION: Human clinical trials were selected for evaluation. DATA SYNTHESIS: Cetirizine, an investigational agent and a potent histamine 1 -antagonist is a piperazine derivative and carboxylated metabolite of hydroxyzine. As a second-generation, nonsedating antihistamine, cetirizine is associated with fewer adverse effects compared with first-generation antihistamines. It appears to be at least as effective as the other nonsedating antihistamines in the treatment of allergic rhinitis, chronic idiopathic urticaria, and pollen-induced asthma. The recommended adult dosage of this agent is 5 or 10 mg/d. CONCLUSIONS: Clinical studies indicate that cetirizine may be more beneficial in some ways than other available agents. Two of these advantages are a rapid onset of action and a once-daily dosing regimen. Future postmarketing surveillance is warranted to further document these findings.