Famprofazone as the Source of Methamphetamine and Amphetamine in Urine Specimen Collected During Sport Competition

Abstract

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.

Interpreting methamphetamine levels in a high-use community

“…Famprofazone is an analgesic that is metabolized to Dand L-MA (5% to 14% of dose excreted as MA) (Cody 1996;Neugebauer et al 1997;Tseng et al 2007); however, it is not approved for use in the USA and is considered an insignificant contributor to the MA in the study (Hope 2010). Benzphetamine in the form of Didrex is prescribed for obesity (Cloyd 1997;Cody and Valtier 1998;Stafford and Radley 2003) Utilization of Benzphetamine in Oregon is considered low because its use is greater among those with health insurance, and Oregon Medicaid (health insurance) has not approved amphetamines for weight loss (Hope 2010).…”

Guilty or not guilty? — False positive results of common medicines in drug tests: review and practical guide

“…This was demonstrated in a case study involving a driver falsely suspected of illicit drug use due to Gewodin consumption [52]. Gewodin was acknowledged as a stimu-lant drug and is included in the prohibited list by the world anti-doping agency [24,53]. Surprisingly, the other stimulant kavain, which contributes to the euphoric, sedative, and anxiolytic effects associated with the consumption of kava (a beverage made from the roots of the kava plant), has also been shown to yield positive results for amphetamines (AMP) [54].…”

Famprofazone Use Can Be Misinterpreted as Methamphetamine Abuse

“…Both drugs are used for pain relief, and the recommended Gewolen usage for an adult is one tablet (25 mg of famprofazone) per dose and twice per day (4). Studies showed that after the administration of 50 mg of famprofazone, the urinary concentrations of MA and AM exceeded 500 ng/mL and 100 ng/mL, respectively (5)(6)(7)(8).…”

“…Several studies have investigated the urinary concentrations of MA after administering 50 mg of famprofazone (5)(6)(7)(8)14). However, the recommended dose of Gewolen is only one tablet (25 mg of famprofazone).…”