PHARMACOLOGICAL CHARACTERIZATION INVIVO OF THE NOVEL OPIATE, BETA-FUNALTREXAMINE

Abstract

The profile of action of .beta.-funaltrexamine (.beta.-FNA), the fumaramate methyl ester derivative of naltrexone, on antinociceptive tests in vivo was investigated in mice. .beta.-FNA demonstrated antinociceptive actions that were of short duration and that appeared to be mediated by kappa receptor interaction. The antagonist actions of .beta.-FNA were of remarkably long duration and were selective toward mu agonist interactions. This profile of action is consistent with the profile of action of .beta.-FNA in vitro. The selective long-lasting antagonism of mu-mediated effects by .beta.-FNA may be of great value in the elucidation of multiple opioid receptor function.