Clostebol (; also known as 4-chlorotestosterone) usually as the

ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ...

clostebol acetate Clostebol acetate (BAN) (brand names Macrobin, Steranabol, Alfa-Trofodermin, Megagrisevit), also known as 4-chlorotestosterone 17β-acetate (4-CLTA) or as 4-chloroandrost-4-en-17β-ol-3-one 17β-acetate, is a synthetic, injected anabolic-androg ...

, is a

synthetic Synthetic things are composed of multiple parts, often with the implication that they are artificial. In particular, 'synthetic' may refer to: Science * Synthetic chemical or compound, produced by the process of chemical synthesis * Synthetic o ...

anabolic–androgenic steroid Anabolic steroids, also known more properly as anabolic–androgenic steroids (AAS), are steroidal androgens that include natural androgens like testosterone as well as synthetic androgens that are structurally related and have similar effects ...

(AAS). Clostebol is the 4-

chloro Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is ...

derivative of the natural hormone

testosterone Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteris ...

. The chlorination prevents conversion to

dihydrotestosterone Dihydrotestosterone (DHT, 5α-dihydrotestosterone, 5α-DHT, androstanolone or stanolone) is an endogenous androgen sex steroid and hormone. The enzyme 5α-reductase catalyzes the formation of DHT from testosterone in certain tissues incl ...

(DHT) while also rendering the chemical incapable of conversion to

estrogen Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal a ...

. Although usually used as an ester including

(Macrobin, Steranabol, Alfa-Trofodermin, Megagrisevit),

clostebol caproate Clostebol caproate (brand name Macrobin-Depot), also known as clostebol hexanoate or chlorotestosterone caproate ( JAN), as well as 4-chlorotestosterone 17β-caproate or as 4-chloroandrost-4-en-17β-ol-3-one 17β-caproate, is a synthetic, inject ...

(Macrobin-Depot), or

clostebol propionate Clostebol propionate (brand name Yonchlon), also known as 4-chlorotestosterone 17β-propionate or as 4-chloroandrost-4-en-17β-ol-3-one 17β-propionate, is a synthetic, injected anabolic-androgenic steroid (AAS) and a derivative of testoster ...

(Yonchlon), unmodified/non-esterified clostebol is also reported to be marketed, under the brand name Trofodermin-S in

Mexico Mexico ( Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guate ...

. Clostebol is a weak AAS with potential use as a performance enhancing drug. It is currently banned by the

World Anti-Doping Agency The World Anti-Doping Agency (WADA; french: Agence mondiale antidopage, AMA) is a foundation initiated by the International Olympic Committee based in Canada to promote, coordinate, and monitor the fight against drugs in sports. The agency's k ...

Chlorodehydromethyltestosterone Chlorodehydromethyltestosterone (CDMT; brand name Oral Turinabol), also known as 4-chloro-17β-hydroxy17α-methylandrosta-1,4-dien-3-one, is an anabolic–androgenic steroid (AAS). It is the 4-chloro-substituted derivative of metandienone (deh ...

(Oral Turinabol), combining the chemical structures of clostebol and

metandienone Metandienone, also known as methandienone or methandrostenolone and sold under the brand name Dianabol (D-Bol) among others, is an androgen and anabolic steroid (AAS) medication which is still quite often used because of its affordability and eff ...

, was widely used in the

East German East Germany, officially the German Democratic Republic (GDR; german: Deutsche Demokratische Republik, , DDR, ), was a country that existed from its creation on 7 October 1949 until its dissolution on 3 October 1990. In these years the state ...

state-sponsored doping program.

Medical uses

Clostebol acetate ointment has ophthalmological and dermatological use.

Side effects

Chemistry

Clostebol, also known as 4-chlorotestosterone or as 4-chloroandrost-4-en-17β-ol-3-one, is a

androstane Androstane is a C19 steroidal hydrocarbon with a gonane core. Androstane can exist as either of two isomers, known as 5α-androstane and 5β-androstane. File:androstane.png, 5α-Androstane File:androstane 5beta.png, 5β-Androstane Pharmacolo ...

steroid A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and ...

and a

derivative In mathematics, the derivative of a function of a real variable measures the sensitivity to change of the function value (output value) with respect to a change in its argument (input value). Derivatives are a fundamental tool of calculus. ...

of testosterone. It is specifically the 4-

chlorinated In chemistry, halogenation is a chemical reaction that entails the introduction of one or more halogens into a compound. Halide-containing compounds are pervasive, making this type of transformation important, e.g. in the production of polym ...

derivative of testosterone.

Society and culture

Nutritional supplements

A related anabolic steroid,

methylclostebol Methylclostebol, also known as 4-chloro-17α-methyltestosterone or as 4-chloro-17α-methylandrost-4-en-17β-ol-3-one, is a synthetic, orally active anabolic-androgenic steroid (AAS) and designer steroid that has been sold on the Internet as a "d ...

, 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.

Publicized abuse cases

Use of clostebol has led to the suspension of a number of athletes in various sports including Freddy Galvis of the

Philadelphia Phillies The Philadelphia Phillies are an American professional baseball team based in Philadelphia. They compete in Major League Baseball (MLB) as a member of the National League (NL) East division. Since 2004, the team's home stadium has been Citize ...

in 2012, Dee Gordon of the

Miami Marlins The Miami Marlins are an American professional baseball team based in Miami. The Marlins compete in Major League Baseball (MLB) as a member club of the National League (NL) East division. The club's home ballpark is LoanDepot Park. The fra ...

in 2016, Olympic athlete

Viktoria Orsi Toth Viktoria Orsi Toth (born 14 August 1990) is an Italian beach volleyball player who plays as a right-side blocker. With partner Marta Menegatti, she achieved a career-high world ranking of No. 7 in June 2016. Her career highlights include two ...

in 2016, Serie A soccer player José Luis Palomino of Club

Atalanta Atalanta (; grc-gre, Ἀταλάντη, Atalantē) meaning "equal in weight", is a heroine in Greek mythology. There are two versions of the huntress Atalanta: one from Arcadia (region), Arcadia, whose parents were Iasus and Clymene (mythology ...

, and

Fernando Tatís Jr. Fernando Gabriel Tatís Medina Jr. (born January 2, 1999), nicknamed "El Niño" or "Bebo", is a Dominican professional baseball shortstop and outfielder for the San Diego Padres of Major League Baseball (MLB). He is the son of former MLB player ...

of the

San Diego Padres The San Diego Padres are an American professional baseball team based in San Diego. The Padres compete in Major League Baseball (MLB) as a member club of the National League (NL) West division. Founded in 1969, the club has won two NL penna ...

in 2022. Tatís Jr, who had missed the entirety of the season due to a broken wrist, accepted the suspension while claiming that it was an inadvertent breach after taking a

ringworm Dermatophytosis, also known as ringworm, is a fungal infection of the skin. Typically it results in a red, itchy, scaly, circular rash. Hair loss may occur in the area affected. Symptoms begin four to fourteen days after exposure. Multiple a ...

medication that he had failed to check the ingredients list for banned substances. and Orlando Galo from Club Sport Herediano in 2022 In 2016, urinalysis resulted in Therese Johaug testing positive for clostebol.

Regulation

In the U.S., clostebol is listed as a Schedule III controlled substance, meaning the U.S. federal government considers it to have a potential for abuse as well as a currently accepted medical use.

References

{{Androgen receptor modulators Androgens and anabolic steroids Androstanes Enones Organochlorides World Anti-Doping Agency prohibited substances