Non-competitive nicotinic cholinergic antagonist; selectively inhibits nicotinic-stimulated catecholamine secretion from chromaffin cells and noradrenergic neurons (IC50 ~ 200 nM). Blocks nicotinic-induced cationic signaling (IC50 ~ 200 - 250 nM) and inhibits nicotinic-agonist induced desensitization of catecholamine release. Also stimulates mast cell release of histamine via a separate mechanism.