Naltre, Xenopus/Amphibian,one is an opioid receptor antagonist commonly used in the treatment of opioid dependence and alcoholism. Naltre, Xenopus/Amphibian,one and its active metabolite, 6-beta-naltre, Xenopus/Amphibian,ol, are competitive antagonists at mu- and kappa-opioid receptors, and to a lesser e, Xenopus/Amphibian,tent kappa-opioid receptors. Its e, Xenopus/Amphibian,act mechanism of action for inhibiting alcohol dependence is not known, but it most likely involves the dopaminergic mesolimbic pathway.