Metabolism and probable active metabolite of alpha-l-acetylmethadol in rat.

alpha-l-Acetylmethadol is being currently evaluated as a substitute for methadone in the treatment of heroin addicts. The metabolites, isolated from urine, liver, and serum, were identified by gas-liquid chromatography. Methadone and its metabolites were found to be present in urine, liver and serum of rats treated with alpha-l-acetylmethadol. The presence of methadone was confirmed by gas-chromatography-mass spectometry. The purpose of this study was to determine whether alpha-l-acetylmethadol is metabolized to methadone, which might explain in part the longer duration of action of alpha-l-acetylmethadol.