Pharmacological actions of levallorphan allyl bromide (CM 32191), a new peripheral narcotic antagonist

A dissociation of the effects of the newly synthesized quaternary ammonium narcotic antagonist, levallorphan allyl bromide (CM 32191) on morphine-induced analgesia and constipation in the mouse is reported. CM 32191 behaved as a pure morphine antagonist on the "in vitro" preparation of longitudinal muscle of guinea-pig ileum and antagonized dose-dependently the peripherally mediated morphine constipation (ID50:15.6 mg/kg) without significantly affecting morphine analgesia (ID50: greater than 80 mg/kg). Its peripheral selectivity was greater than that of another quaternary ammonium compound, N-methyl naloxone. It is proposed as a useful pharmacological tool to differentiate the peripherally mediated from the centrally mediated effects of opioids.