High affinity H3 receptor antagonist (Ki = 43.8 nM). Displays selectivity against H1 and H2 receptors (IC50 >10 μM). Increases the release of histamine in the cerebral cortex. Displays no activity at histamine methyltransferase in vitro at concentrations up to 3 μM. Brain penetrant. Purity 98%. MW (observed): 317.47