Mequitazine (CAS No.: 29216-28-2) is an effective, non-sedating, long-acting histamine H1 receptor antagonist, mainly used to treat allergic diseases such as allergic rhinitis, urticaria, and allergic conjunctivitis. Its mechanism of action is to selectively block H1 receptors, inhibiting histamine-mediated allergic reactions and alleviating symptoms such as itching and redness/swelling. Mequitazine shows moderate antihistamine activity in in vitro experiments, and the specific activity level may vary depending on experimental conditions and design. This drug is commonly used in cell and animal models to study the mechanisms of allergic reactions and to evaluate the efficacy of antihistamines. The dose or concentration used in experiments typically depends on the experimental design and research objectives.