Testing for GW501516 (cardarine) in human hair using LC/MS-MS and confirmation by LC/HRMS.

GW501516, also known as GW-1516 or cardarine and endurobol, is a peroxisome proliferator-activated receptor delta (PPAR-δ) agonist. Activation of the receptor will increase fat-burning capacity and muscle production, as it changes the body's fuel preference from glucose to lipids. GW501516 has no therapeutic use, but can be abused for performance-enhancing purposes using the oral route, at dosages of 10 to 20 mg per day, for 6 to 8 weeks. Both athletes and amateurs can abuse GW501516 as the drug can be easily obtained via the Internet. Since January 2009, the list of prohibited substances and methods of doping as established by the World Anti-Doping Agency includes GW-501516, first as a gene doping substance and now in the S4.5 Metabolic modulators class. It is prohibited at all times. Using LC/MS-MS and confirmation by LC/HRM, after methanol incubation of 20 mg with ultrasound for 1 hour, GW501516 was identified in the hair of a male abuser at 32 and 22 pg/mg in 2 × 2 cm segments. The result is the first evidence that this compound with a carboxylic acid function is incorporated in human hair.