Opioid-positive urine drug screen during treatment with oral naltrexone and the clinical implications.

Introduction: Naltrexone is an opioid antagonist that is FDA approved to treat alcohol dependence and opioid dependence. It is available as an oral tablet and an extended-release injectable suspension. Naltrexone is metabolized to the primary metabolite, 6-β-naltrexol, and to 2 minor metabolites, 2-hydroxy-3-methoxy-6-β-naltrexol and 2-hydroxy-3-methyl-naltrexone.