Pharmacology Of Levocabastine

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.
Pharmacodynamics	Levocabastine is a selective histamine H1-receptor antagonist exerting inhibitory effects on the release of chemical mediators from mast cells and on the chemotaxis of polymorphonuclear leukocytes and eosinophils. Both histamine and antigens induced conjunctivitis can be inhibited by levocabastine. Levocabastine can also reduce symptoms of allergic rhinitis by preventing an increase in vascular permeability of nasal mucosa.
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.
Absorption	After instillation in the eye, levocabastine is systemically absorbed, albeit at low levels.
Volume of distribution	Not Available
Protein binding	Not Available
Metabolism	Mostly unchanged. 10 to 20% is metabolized to the acylglucuronide of levocabastine.
Route of elimination	Not Available
Half life	36 hours (after oral administration)
Clearance	Not Available
Toxicity	Adverse effects include visual disturbances, dry mouth, cough, nausea, eyelid edema and lacrimation.