Olopatadine is a selective histamine H1 antagonist that binds to the histamine H1 receptor. This blocks the action of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms brought on by histamine. Olopatadine is devoid of effects on alpha-adrenergic, dopamine and muscarinic type 1 and 2 receptors.
Used to treat allergic conjunctivitis (itching eyes), olopatadine inhibits the release of histamine from mast cells. It is a relatively selective histamine H1 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.
The mono-desmethyl and the N-oxide metabolites have been detected at low concentrations in the urine.