Stanozolol (also known as winstrol) is a 17-alpha-alkylated derivative of dihydrotestosterone (DHT) with low androgenic qualities yet highly anabolic. It was first developed in 1962 by American global pharmaceutical company Sterling-Winthrop Laboratories to increase lymphocyte count and CD8+ cell numbers, but to decrease CD4+ and CD3+ in postmenopausal women using it for osteoporosis. This effect would plausibly be useful for treatment of autoimmune disorders. Winstrol is useful in treatment of hereditary angioedema. It also influences some immunological processes.

Now stanozolol is produced for sale in two forms: tablets and injections. Stanozolol is the second most widely used oral steroid, succeeded in popularity only by methandienone. Stanozolol tablets have a short life time (about 9 hours) as compared against injectable stanozolol. The injectable version of stanozolol differs from other injectable anabolic steroids in being an aqueous suspension of fine particles of steroid, instead of being an oil solution of an esterified compound. For this reason, it has unusual pharmacokinetics which do not follow the classic half-life pattern. Instead, there is a sustained effect which slowly tapers. The duration of action is probably at least a week. Individual particles of stanozolol may remain at the injection site for extended periods of time. However, Pharmacom Labs managed to create an oil-based version of stanozolol, which can be mixed with all other oil and has no flaws of the suspension. All three forms are characterized by good bioavailability.

Although stanozolol is a DHT based compound, its activity is much milder than this androgen in nature. As DHT derivative Stanozolol can`t convert into estradiol, hence aromatase inhibitors are not required when taking this compound. As a result stanozolol does not cause water retention. On the contrary, it possess a diuretic effect. So, instead of bulk look winstrol produces a lean, quality look without excess subcutaneous water retention. This makes it an excellent steroid to use throughout cutting cycles, when getting rid of superfluous water and fat as well as strongly defined, hard looking muscularity are a major goal. Due to its features stanozolol is highly regarded among athletes of strength/speed sports like track and field.

As for bodybuilders, stanozolol has one interesting peculiarity demanded among them. It consists in the profound ability to lower sex hormone-binding globulin (SHBG) level resulting in efficiency growing of other steroids in stack with it. In particular, it raises the amount of biologically active free testosterone circulating in the blood. For this reason it is advisable always to use stanozolol in stack with testosterone. Another one reason for this is as follows: winstrol may be more prone than other anabolic steroids to increasing tendon brittleness. This happens due to winstrol`s possibility to dry out the joint fluid, which can lead to joint pain and damages. Also both stanozolol forms: tablets and injections have been noted to provoke adverse changes in cholesterol levels. Hence, monitoring of the lipid profile of the body (blood works) during cycle is advisable.

To summarize, stanozolol is generally recommended for athletes having sufficient muscle bulk, but wishing to improve endurance and increase muscle relief and hardness.