Ebast Mechanism of Action

Antiallergic.
Ebastine is a 2nd-generation antihistamine which undergoes transformation to its active metabolite, carebastine. Its antihistaminic and antiallergic effects have been demonstrated in in vitro and in vivo studies. Ebastine is a long-acting, nonsedating histamine H₁-receptor antagonist which binds preferentially to peripheral H₁-receptors in vivo. It has shown antihistamine and antiallergic activity in healthy volunteers and patients with allergies and protected against histamine-induced bronchoconstriction in patients with asthma. Significant symptom improvement is observed in patients with seasonal or perennial allergic rhinitis or chronic idiopathic urticaria. Most of the new H₁ antagonists do not accumulate in tissues during repeated administration and have a residual action of <3 days after a short course has been completed. Tachyphylaxis or loss of peripheral H₁-receptor blocking activity during regular daily use has not been found for ebastine.
Pharmacokinetics: Orally administered ebastine is well absorbed and is extensively distributed into body tissues. It is protein-bound. Most of the new H₁ antagonists do not accumulate in tissues during repeated administration and have a residual action of <3 days after a short course has been completed. Ebastine is extensively and rapidly metabolized to its active metabolite; carebastine has a half-life of approximately 15 hrs and duration of action of at least 24 hrs.