Clostebol (INNTooltip International Nonproprietary Name; also known as4-chlorotestosterone) is asyntheticanabolic–androgenic steroid (AAS). Clostebol is the 4-chloro derivative of the natural hormonetestosterone. The chlorination prevents conversion todihydrotestosterone (DHT) while also rendering the chemical incapable of conversion toestrogen.[citation needed] Although usually used as an ester includingclostebol acetate (Macrobin, Steranabol, Alfa-Trofodermin, Megagrisevit),clostebol caproate (Macrobin-Depot), orclostebol propionate (Yonchlon), unmodified/non-esterified clostebol is also reported to be marketed, under the brand nameTrofodermin-S inMexico.[2]
Clostebol acetate ointment has ophthalmological and dermatological use.[5] In some countries, such as Italy, it is available without a prescription as a topical cream or spray for the treatment of (infected) skin wounds such as abrasions, erosions, fissures, burns and to help speed up the healing of the area.
In Italy, it is sold as a spray and cream, with the brand nameTrofodermin, containing a combination of clostebol acetate andneomycin.[6]
Clostebol, also known as 4-chlorotestosterone or as 4-chloroandrost-4-en-17β-ol-3-one, is asyntheticandrostanesteroid and aderivative of testosterone. It is specifically the 4-chlorinated derivative of testosterone.
A related anabolic steroid,methylclostebol, is a common additive in so-called dietary supplements, generally listed in the convoluted form 4-chloro-17α-methyl-androst-4-en-17β-ol-3-one.[7]
Italian tennis playerJannik Sinner tested positive for clostebol in two different urine samples on 8 March and 10 March 2024.[16] The International Tennis Integrity Agency (ITIA) found Sinner was inadvertently contaminated with the substance by his physiotherapist who had been applying the healing spray Trofodermin, available over-the counter in Italy, to treat a cut on his own hand and had then carried out treatments on Sinner.[17] Sinner was stripped of $325,000 in prize money and 400 ranking points earned at theIndian Wells Open, but wasn't suspended initially because an independent tribunal ruled that it was not intentional.[16][17][18] However, theWorld Anti-Doping Agency (WADA) announced in February 2025 they entered a "case resolution agreement" with Sinner.[19][20] WADA accepted the cause and explanation of the positive test but stated "an athlete bears responsibility for the entourage’s negligence". A three-month suspension was handed down with Sinner being ineligible from tennis competition from 9 February to 4 May 2025.[21][22]
In the U.S., clostebol is listed as aSchedule III controlled substance,[7] meaning the U.S. federal government considers it to have a potential for abuse as well as a currently accepted medical use.
^de la Torre X, Colamonici C, Iannone M, Jardines D, Molaioni F, Botrè F (November 2020). "Detection of clostebol in sports: Accidental doping?".Drug Testing and Analysis.12 (11–12):1561–1569.doi:10.1002/dta.2951.PMID33119965.
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