Carbon-13 nuclear magnetic resonance identification of 2-hydroxy-3-O-methyl-6beta-naltrexol as a minor naltrexone metabolite.

A carbon-13 nuclear magnetic resonance comparison of synthetic and biological samples was used to identify unequivocally 2-hydroxy-3-O-methyl-6beta-naltrexol as a minor naltrexone metabolite in humans. This study points up the increasing usefulness of natural abundance carbon-13 nuclear magnetic resonance techniques in metabolism studies.