Stanozolol or Turinabol: What's the Difference

Stanozolol and turinabol are two 17α-alkylated steroids that most often feature in the history of doping scandals. The first became famous after the 1988 Seoul Olympics, the second — as the main instrument of the GDR's state program and the «hero» of mass reanalyses of Olympic samples. The editorial team explains how these substances differ in structure, action and risks.

Structure: pyrazole versus chlorine

Stanozolol is a derivative of dihydrotestosterone, to whose ring A a five-membered heterocyclic pyrazole ring containing two nitrogen atoms is attached. This structure, unusual for steroids, makes the molecule more polar and changes its interaction with carrier proteins in the blood. In addition, there is a methyl group at position 17α.

Turinabol (4-chlorodehydromethyltestosterone) is built differently. Its basis is testosterone with a double bond between the first and second carbon atoms (as in methandienone), a chlorine atom at the fourth position and a 17α-methyl group. The chlorine blocks aromatization and weakens the androgenic properties compared with methandienone.

Thus, stanozolol belongs to the «family» of DHT, and turinabol — to the «family» of testosterone. Neither substance practically converts into estrogens, but for different reasons: stanozolol — because DHT derivatives are not a substrate of aromatase at all, turinabol — because of the chlorination.

Both compounds are united by 17α-alkylation, which provides oral bioavailability and at the same time causes the characteristic load on the liver. This common feature explains why the side-effect profiles are similar in many respects.

Dosage forms and medical past

Stanozolol was produced under the name Winstrol in tablet form. One of the main indications in the USA was the prevention of attacks of hereditary angioedema — a rare genetic disease in which androgens raise the level of the deficient protein C1 inhibitor. Later the drug was withdrawn from circulation in the USA, and modern specific treatment methods appeared for this disease.

A feature of stanozolol is the existence of an injectable form as an aqueous microcrystalline suspension. It was used primarily in veterinary medicine. An aqueous suspension, unlike oil solutions of esters, does not create a lasting depot, and the injections are often described as painful.

Turinabol formally had the status of a medicine in the GDR, but its main use was the state sports program. After the reunification of Germany, production was stopped, and the drug has no modern medical indications.

So stanozolol, unlike turinabol, has a limited but real clinical history. This means that a little more is known about it from medical sources, in particular regarding the effect on lipids and the liver under controlled conditions.

How they affect the body

Both substances are androgen receptor agonists and stimulate protein synthesis in muscles. In the sports community they are usually associated not with a large gain in mass, but with «quality» — the absence of estrogenic fluid retention. However, there is little scientifically substantiated data on the real magnitude of these effects in humans.

A characteristic property of stanozolol is a pronounced decrease in the level of sex hormone-binding globulin (SHBG). Because of this, the proportion of free androgens in the blood, including one's own testosterone, increases. For turinabol a decrease in SHBG has also been described, as for other oral androgens, but it is precisely stanozolol that is most often mentioned in reviews in this respect.

Both substances suppress the secretion of LH and FSH. Even without noticeable «external» side effects, this means a decrease in one's own testosterone and spermatogenesis. Recovery after discontinuation can last from several weeks to many months.

Finally, both affect lipid metabolism. Oral 17α-alkylated androgens, passing through the liver in high concentrations, stimulate hepatic lipase, which leads to a sharp decrease in HDL. For stanozolol this effect is documented in clinical studies.

Specific risks of each substance

The common risks are clear: hepatotoxicity (cholestasis, elevated enzymes, in rare cases peliosis and liver tumors), an unfavorable lipid panel, increased blood pressure, suppression of the hormonal axis, virilization in women. The review by Solimini et al. (2017) gives examples of severe liver damage against the background of illegal use of 17α-alkylated steroids.

For stanozolol, in the sports community complaints about joints and ligaments are often mentioned — pain and a feeling of «dryness». Scientifically these reports are poorly studied, but the risk of tendon injuries against the background of anabolic steroids is itself discussed in the literature, since muscle strength grows faster than connective tissues adapt.

For turinabol, the specific background is the historical data on the consequences in GDR athletes. Franke and Berendonk described virilization in women, including irreversible changes, as well as other medical problems associated with systematic intake of the drug from adolescence.

• Stanozolol:a sharp decrease in HDL and SHBG, complaints from the joints, painfulness of injections of the aqueous suspension and the risk of abscesses.
• Turinabol:hepatotoxicity, virilization in women, a complete absence of modern clinical data and quality control.
• Both:suppression of fertility, cardiovascular risks, dependence in some users.

It is important to take the source into account as well: both substances on the modern market come mainly from illegal production. A discrepancy between the composition and the label is a common phenomenon, so the real risks may be higher than expected.

Two doping stories

Stanozolol became a symbol of doping after the 1988 Olympic Games, when this very substance was detected in the sample of sprinter Ben Johnson, and his gold medal in the 100 m was annulled. This case significantly influenced the development of the global anti-doping system.

For a long time the main marker of stanozolol in anti-doping laboratories was the metabolite 3'-hydroxystanozolol. Later, methods for detecting additional metabolites appeared, which increased the detection window.

Turinabol returned to the news in the 2010s. The description of long-lived metabolites (Sobolevsky, Rodchenkov, 2012) made it possible, during the reanalysis of samples from the 2008 and 2012 Olympics, to detect a significant number of violations and strip athletes of awards. Stanozolol also frequently appeared among the detected substances.

Both substances belong to class S1 of the WADA Prohibited List and are prohibited at all times. The history of reanalyses shows that for an athlete the risk of sanctions persists for years after competitions.

Editorial conclusions

Stanozolol is a DHT derivative with a pyrazole ring that exists in tablets and an aqueous suspension and has a limited medical history. Turinabol is a chlorinated derivative of methandienone with no modern medical indications.

Both do not aromatize, are 17α-alkylated, load the liver, sharply worsen the lipid profile and suppress the hormonal axis. Stanozolol is especially known for reducing SHBG and HDL, turinabol — for the history of state doping and the consequences for female athletes.

Both substances became examples of how modern analytical chemistry catches up with doping even years later.

We also recommend reading our materials «Stanozolol vs Turinabol: what to choose and for whom», on sex hormone-binding globulin and on liver tests when taking hormonal drugs.

References

1. Kicman AT. Pharmacology of anabolic steroids. Br J Pharmacol. 2008;154(3):502–521.
2. Franke WW, Berendonk B. Hormonal doping and androgenization of athletes: a secret program of the German Democratic Republic government. Clin Chem. 1997;43(7):1262–1279.
3. Sobolevsky T, Rodchenkov G. Detection and mass spectrometric characterization of novel long-term dehydrochloromethyltestosterone metabolites in human urine. J Steroid Biochem Mol Biol. 2012;128(3–5):121–127.
4. Schänzer W. Metabolism of anabolic androgenic steroids. Clin Chem. 1996;42(7):1001–1020.
5. Pope HG Jr, Wood RI, Rogol A, et al. Adverse health consequences of performance-enhancing drugs: an Endocrine Society scientific statement. Endocr Rev. 2014;35(3):341–375.
6. Solimini R, Rotolo MC, Mastrobattista L, et al. Hepatotoxicity associated with illicit use of anabolic androgenic steroids in doping. Eur Rev Med Pharmacol Sci. 2017;21(1 Suppl):7–16.
7. World Anti-Doping Agency. International Standard — Prohibited List. Montreal: WADA; актуальна редакція.