A competitive antagonist of nAChRs and non-depolarizing muscle relaxant; inhibits acetylcholine stimulation of human adult muscle nAChRs (IC50 = 10 nM); inhibits mouse nAChRs (IC50s = 54 and 115 nM for adult and embryonic receptors, respectively); increases apoptosis in HUVEC cells; decreases proliferation of HepG2 and HUVEC cells in vitro; reduces the magnitude of electrically-evoked twitch tensions in isolated rat extensor digitorum longus and soleus sciatic nerve-muscle preparations; blocks electrically-evoked muscle twitches in anesthetized rabbits (ED95 = 0.04 mg/kg)