Bromazine
Bromodiphenhydramine is a brominated derivative of diphenhydramine, an ethanolamine derivative and histamine H1 receptor antagonist with anti-allergic, sedative, antiemetic and anticholinergic properties. Bromazine competitively and selectively blocks central and peripheral histamine H1 receptors, thereby alleviating the symptoms caused by endogenous histamine on bronchial, capillary and gastrointestinal (GI) smooth muscles. This prevents histamine-induced bronchoconstriction, vasodilation, increased capillary permeability, itching, and spasmodic contractions of GI smooth muscle. In addition, bromazine binds to and blocks peripheral and central muscarinic receptors.