A histamine H1 receptor antagonist (Ki = 38.4 nM in cell membranes expressing human recombinant H1 receptors); reduces histamine-induced IL-6 and IL-8 production in human conjunctival epithelial cells (IC50s = 1 and 0.652 μM, respectively); prevents anaphylaxis in rabbits sensitized to egg albumin and increases survival in a guinea pig model of histamine-induced bronchospasm; eliminates atrial fibrillation induced by acetylcholine and isoproterenol in isolated rabbit hearts by increasing the atrial effective refractory period and interatrial conduction time in a dose-dependent manner; binds to NMDA receptors (Ki = 13 μM) and reduces glutamate-induced toxicity in cerebellar granule cells (EC50 = 13 μM)