Detection of clostebol in sports: Accidental doping?

The detection of clostebol misuse in sports has been growing recently, especially in Italy, due to the ample availability of pharmaceutical formulations containing clostebol acetate (Trofodermin®) and the use of more sensitive instrumentation by the antidoping laboratories. Most of these cases have been claimed to be related to a nonconscious use of the drug or through contact with relatives or teammates using it. We have investigated, through the application of the well‐known and currently used gas chromatographic mass spectrometric procedures, the likelihood of these allegations and have demonstrated that after a single transdermal administration of 5 mg of clostebol acetate and a transient contact with the application area, it is possible to generate adverse analytical findings in antidoping controls. We have reviewed the Phase I and Phase II clostebol metabolism in order to generate evidences that may help the sport authorities reviewing these cases. The main clostebol metabolite (4‐chloro‐androst‐4‐en‐3α‐ol‐17‐one, M1) generally used at the screening level as well as other three metabolites (M2–M4) are mainly excreted as glucuronides, whereas M5 (4ζ‐chloro‐5ζ‐androstan‐3β‐ol‐17‐one) is predominantly excreted as sulfate. Neither the 5α‐reductases activity (impaired by the presence of the chlorine in C4) nor specific sulfotransferases present in the skin allowed a clear distinction of the administration route. Studies with a larger number of volunteers and probably investigating another physiological fluid allowed in antidoping such as blood are needed for a deeper investigation. It is not unreasonable to establish a reporting level for M1, maybe creating some false negatives but excluding nonintentional doping scenarios. Clostebol cases increased in the last years in specific countries because of a widespread use of Trofodermin®, a cream containing clostebol acetate. Incidental contact with the skin where the cream is applied may produce adverse analytical findings in doping analyses. Investigations aiming to produce evidences to help the results management of these cases are necessary. We report some metabolic approaches based on urine analyses, but most probably the use of other matrices as blood are needed.