Emedastine is a relatively selective, histamine H<sub>1</sub> antagonist. In vitro examinations of emedastine's affinity for histamine receptors demonstrate relative selectivity for the H<sub>1</sub> 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. (en)
Approximately 44% of the oral dose is recovered in the urine over 24 hours with only 3.6% of the dose excreted as parent drug. Two primary metabolites, 5- and 6-hydroxyemedastine, are excreted in the urine as both free and conjugated forms. (en)