Olopatadine belongs to a kind of antihistamine reagent. It is a relatively selective H1-receptor antagonist and can inhibit the histamine release process from the mast cell, subsequently leading to temporary relief on the negative symptoms associated with histamine. It is devoid of effects on alpha-adrenergic, dopamine and muscarinic type I and II receptors. Its 0.1% solution can be used for topical administration to the eyes. It is indicated for the treatment of itching associated with allergic conjunctivitis.