Mechanism of action levocabastine is a potent, selective histamine h1-receptor antagonist. it works by competing with histamine for h1-receptor sites on effector cells. it thereby prevents, but does not reverse, responses mediated by histamine alone. levocabastine does not block histamine release but, rather, prevents histamine binding and activity. levocabastine also binds neurotensin 2 receptors and serves as a neurotensin agonist. this can induce some degree of analgesia.indication as an ophthalmic for the temporary relief of the signs and symptoms of seasonal allergic conjunctivitis. also used as a nasal spray for allergic rhinitis.