Metabolic production of amphetamine following administration of clobenzorex

Many of the anorectic drugs that are metabolized to amphetamine and/or meth amphetamine pose significant concerns in the interpretation of amphetamine- positive drug testing results. One of these drugs-clobenzorex-has been show n to produce amphetamine. Thirty milligrams of clobenzorex hydrochloride, i n the from of a single Asenlix capsule (Roussel, Mexico), were administered orally to five human volunteers with no history of amphetamine, methamphet amine or clobenzorex use. Following administration, urine samples (total vo id volume) were collected an lib for seven days and pH, specific gravity an d creatinine values were determined. To determine the excretion profile of amphetamine and parent drug, samples were extracted, derivatized, and analy zed by gas chromatography/mass spectrometry (GC/MS) using a standard amphet amine procedure with additional monitoring of ions at m/z 91, 118, 125 and 364 for the detection of clobenzorex. Peak concentrations of amphetamine we re detected at 4 to 19 h postdose and ranged from approximately 715 to 2474 ng/mL amphetamine. Amphetamine could be detected (>5 ng/mL) in the urine i n one subject for up to 116 h postdose. GC/MS was also used to determine th e enantiomeric composition of the metabolite, amphetamine. This analysis re vealed the metabolically derived amphetamine was only the d-enantiomer. Thi s differs from previous literature which indicates clobenzorex is the racem ic N-orthochlorobenzyl derivative of amphetamine.