Olopatadine is an anti‐histaminic, with selective H1 ‐receptor
antagonist activity. Its principal effects are mediated via inhibition of
H1 receptors. Olopatadine hydrochloride was patented on 1st
December 2007 by Kyowa Hakko Kogyo Company Ltd, Japan. These
drugs selectively bind to H1 receptors there by blocking the actions
of endogenous Histamine. They act on the bronchi, capillaries, and
other smooth muscles. Olopatadine is an inhibitor of the release of
Histamine from the mast cell and a relatively selective H1 receptor
antagonist that inhibits the in vivo and in vitro type 1 immediate
hypersensitivity reaction including inhibition of histamine induced
effects on human conjunctival epithelial cells.