Stanozolol is a highly modified sythetic version of DHT that is commonly called by the name Winstrol. As you can see, there is an additional ring system attached to the traditional A-ring of the steroid structure. The binding data for winstrol shows it to have very poor binding for the androgen receptor1. However the half-life of 9 hours for winstrol is quite long making up for the lower affinity2.
Stanozolol is incapable of being converted to estrogenic metabolites and is already 5-alpha reduced so it cannot be reduced further but does seem to have some antiaromatase activity. Stanozolol has minimal binding to SHBG so it circulates in the “free” state3. It has been shown that although stanozolol does not interact directly with the glucocorticoid receptor, it does interact with two glucocorticoid binding proteins known as STBP and LAGS4,5. This interaction “bumps off” bound cortisol into free circulation. At the same time, stanozolol has been shown to interfere with cortisol release from the adrenal gland. This results in reduced cortisol levels with chronic treatment.
In fact, many people notice severe joint pain when using stanozolol, especially when used alone. This can result in a rebound effect in cortisol production when going off stanozolol. Even though stanozolol has a very large anabolic to androgenic ratio, it is in fact quite androgenic. The anti-glucocorticoid effect of this drug likely augments its anabolic/androgenic ratio beyond that of its androgen receptor binding effects alone. Stanozolol decreases TBG levels but not as much as some of the other common AAS6.
In addition to tablets for oral administration, stanozolol is also available as water based suspension for injection. Because it is not esterified, this steroid needs to be injected every day. Also, water based injections are a lot more prone to bacterial contamination so more care is needed to keep a multi-use bottle sterile. The relatively large crystal size of some preparations limits the size of needle that can be used because the crystals will jam smaller needles. There are some formulations available that have smaller crystal size; however, these seem to have a shorter half-life – most likely due to the crystals dispersing faster within the muscle. Because it is C-17 alpha alkylated, stanozolol has the potential for liver toxicity though this is somewhat reduced with the injectable form because a lower dose is often used. Stanozolol has a favorable anabolic to androgenic ratio but most do not consider it to be very effective. This is largely due to the fact that stanozolol does not result in large water weight gains.
Other names include: Stromba, Strombaject, Stanazolic, Stanol
1. Saartok T, Dahlberg E, Gustafsson JA: Relative binding affinity of anabolic-androgenic steroids: comparison of the binding to the androgen receptors in skeletal muscle and in prostate, as well as to sex hormone-binding globulin. Endocrinology. Jun;114(6):2100-6, 1984
2. Feldkoren BI, Andersson S. Anabolic-androgenic steroid interaction with rat androgen receptor in vivo and in vitro: a comparative study. J Steroid Biochem Mol Biol. 94(5):481-7, 2005
3. Schanzer W, Donike M: Metabolism of boldenone in man: gas chromatographic/mass spectrometric identification of urinary excreted metabolites and determination of excretion rates. Biol Mass Spectrom. Jan;21(1):3-16, 1992
4. Betancor-Hernández E, Pérez-Machín R, Henríquez-Hernández L, Mateos-Díaz C, Novoa-Mogollón J, Fernández-Pérez L. Photoaffinity labeling identification of thyroid hormone-regulated glucocorticoid-binding peptides in rat liver endoplasmic reticulum: an oligomeric protein with high affinity for 16beta-hydroxylated stanozolol. J Steroid Biochem Mol Biol. 87(4-5):253-64, 2003
5. Stanozolol and danazol, unlike natural androgens, interact with the low affinity glucocorticoid-binding sites from male rat liver microsomes. Fernández L, Chirino R, Boada LD, Navarro D, Cabrera N, del Rio I, Díaz-Chico BN. Endocrinology. 134(3):1401-8, 1994
6. Barbosa J, Seal US, Doe RP: Effects of anabolic steroids on hormone-binding proteins, serum cortisol and serum nonprotein-bound cortisol. J Clin Endocrinol Metab. Feb;32(2):232-40, 1971
Adapted with permission from Seth Robert’s Anabolic Pharmacology, all rights reserved.