Olopatadine

**Semantic type:** Pharmacologic Substance

**Definition:** A dual action selective histamine H1 receptor antagonist and mast cell stabilizer with anti-allergic activity. Olopatadine stabilizes mast cells and prevents histamine release from mast cells. In addition, this agent also blocks histamine H1 receptors, thereby preventing histamine from binding to these receptors. Both actions prevent the effects of histamine on capillaries, bronchial smooth muscle, and gastrointestinal (GI) smooth muscle, including histamine-induced vasodilation, increased capillary permeability, bronchoconstriction, and spasmodic contraction of GI smooth muscle. This drug also prevents histamine-induced pain and itching of mucous membranes.

**Synonyms:** - OLOPATADINE