Is the undetectability in hair of a single ostarine dose due to the lack of its excretion in sweat?

Ostarine, also known as S22, MK2866 or enobosarm, is a selective androgen receptor modulator (SARM), listed as a member of the S1.2 class "other anabolic agents" of the World Anti-Doping Agency (WADA), forbidden in- and out-competition. At this time, ostarine tests in supplements and hair or nail specimens represent the major requests at the laboratory among all the doping agents. To be pharmacologically active, ostarine must be taken on a long-term basis, over several weeks. As a consequence, it is admitted that the drug will show up in hair when used for doping purposes. However, it has been continuously challenged that the minimal detectable dose remains unknown. One of the authors took a 10 mg dose and a hair specimen was collected one month after. No ostarine was identified, although the limit of quantitation of the method is 0.5 pg/mg. As sweat is acknowledged to play a major role in drug incorporation into hair, the subject has worn 6 sweat patches (PharmChekTM, Sudormed Inc) up to 72 hours. The limit of quantitation was 10 pg/patch, but no ostarine was identified. The lack of ostarine secretion into sweat can be a reason why a single dose of the drug is not detectable in hair. (c) 2023 Soci ' et ' e Franc,aise de Toxicologie Analytique. Published by Elsevier Masson SAS. All rights reserved.