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.