Famprofazone as the source of methamphetamine and amphetamine in urine specimen collected during sport competition.

During a sport competition event in Taiwan, one urine specimen was found positive for both methamphetamine (2688 ng/mL) and amphetamine (462 ng/mL). The specimen donor claimed that she had taken Gewolen (a nonprescription drug manufactured in Taiwan) for treating abdominal pain and the medication was presented. Laboratory investigation confirmed that Gewolen contains famprofazone, which is known to metabolize to methamphetamine and amphetamine and is included in the prohibited list of the World Anti-Doping Agency. Study on the excretion profiles of three volunteers ingesting 50 mg famprofazone produced the following patterns similar to that observed in the case specimen: (a) the ratio of methamphetamine to amphetamine was approximately 6 to 1; (b) d- and l-enantiomers of both methamphetamine and amphetamine were present, while the amount of l-methamphetamine was 3-4-fold greater than its counterpart. The data suggested that famprofazone (as the ingredient of Gewolen) was likely the source of the prohibited drugs found in the case specimen.