By Seth Roberts
Pharmacology is the study of drugs and their effects. Anabolic pharmacology is the study of drugs that have a growth-promoting effect in muscle. This column will explore anabolic pharmacology by profiling a different anabolic drug and its effects each month. The focus of discussion this month will be the anabolic androgenic steroid, stanozolol.
Stanozolol is a highly-modified synthetic version of dihydrotestosterone (DHT) that was originally sold under the trade 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 stanozolol shows it to have very poor binding for the androgen receptor. However, the half-life of nine hours for this steroid is quite long— making up for the lower affinity. Stanozolol is incapable of being converted to estrogenic metabolites through aromatization, and is already 5-alpha reduced, so it cannot be reduced further— but does seem to have some anti-aromatase activity.
Stanozolol has minimal binding to sex hormone-binding globulin (SHBG), so it circulates for the most part in the ‘free’ state. 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 LAGS. 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 usage. 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 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 thyroxine-binding globulin (TBG) levels but not as much as some of the other common anabolic-androgenic steroids.
In addition to tablets for oral administration, stanozolol is 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 stanozolol is C-17 alpha-alkylated, it has the potential for liver toxicity— but this is somewhat reduced with the injectable form because a lower overall 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.
source:musculardevelopment.com
