Emedastine

Emedastine (trade name Emadine) is a second generation antihistamine used in eye drops to alleviate the symptoms of allergic conjunctivitis. It acts as a H₁ receptor antagonist. It works by blocking the action of histamine that causes allergic symptoms. It is used in form of the difumarate. The formation of emedastine difumarate is a white, crystalline, water-soluble fine powder. Emedasine is applied as an eye drop with 2 times a day. When the patients with allergic conjunctivitis were treated with 0.05% emedastin difumarate ophthalmic solution for six weeks, the signs and symptoms such as redness, itching and swelling of the eyes were relieved. Emedastine appears to be devoid of effects on adrenergic, dopaminergic and serotonin receptors. This drug was developed by alcon which is global medical company specializing in eye care products.

Pharmacodynamics

Emedastine is significantly selective to H₁ histamine receptors (K_i = 1.3 nM), whereas its affinities for other histamine receptors were low (H₂: K_i = 49067 nM and H₃: K_i = 12430 nM) ub in vitro study. Topical ocular administration of emedastine inhibits histamine-stimulated vascular permeability in the conjunctiva as a concentration-dependent manner in in vitro study.