Promethazine

**Semantic type:** Organic Chemical|Pharmacologic Substance

**Definition:** A phenothiazine derivative with antiemetic and antihistaminic properties. Promethazine antagonizes the central and peripheral effects of histamine mediated by histamine H1 receptors. The effects include bronchoconstriction, vasodilation and spasmodic contractions of gastrointestinal smooth muscle. In addition, this agent binds to muscarinic receptors, resulting in anticholinergic and antiemetic activities.

**Synonyms:** - PROMETHAZINE