NCIt 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.;