Metabolic profile of famprofazone following multidose administration

Abstract

One of the 14 different drugs known to be metabolized to methamphetamine and/or amphetamine is famprofazone, a component in the multi-ingredient formulation Gewodin®. Because of its conversion to methamphetamine and amphetamine, which can result in positive drug-testing results, the excretion pattern of these metabolites is critical for proper interpretation of drug-testing results. Multiple doses of famprofazone were administered to healthy volunteers with no previous history of methamphetamine, amphetamine, or famprofazone use. Following administration, urine samples were collected ad lib for nine days, and pH, specific gravity, and creatinine values were determined. To determine the methamphetamine and amphetamine excretion profile, samples were extracted, derivatized, and analyzed by gas chromatography-mass spectrometry (GC-MS). Peak concentrations of methamphetamine ranged from 5327 to 14,155 ng/mL and from 833 to 3555 ng/mL for amphetamine and were reached between 12:22 and 48:45 h post initial dose. There were 15-19 samples per subject that were positive under HHS testing guidelines, with the earliest at 03:37 h post initial dose and as late as 70:30 h post last dose. Methamphetamine and amphetamine were last detected (LOD ≥ 5 ng/mL) up to 159 h and 153 h post last dose for methamphetamine and amphetamine, respectively. GC-MS was also used to determine the enantiomeric composition of methamphetamine and amphetamine. This analysis revealed both enantiomers were present in a predictable pattern.