Indication For the temporary relief of the signs and symptoms of allergic conjunctivitis. Pharmacodynamics Emedastine is a relatively selective H1-receptor antagonist. Mechanism of action Emedastine is a relatively selective, histamine H1 antagonist. In vitro examinations of emedastine's affinity for histamine receptors demonstrate relative selectivity for the H1 histamine receptor. In vivo studies have shown concentration-dependent inhibition of histamine-stimulated vascular permeability in the conjunctiva following topical ocular administration. Emedastine appears to be devoid of effects on adrenergic, dopaminergic and serotonin receptors.