GTx-024, S22, SARM S-22, MK-2866 or Enobosarm

Also known as: S22, SARM S-22, MK-2866 and Enobosarm

What are SARMs (Selective Androgen Receptor Modulators)?

Selective Androgen Receptor Modulators (abbreviation: SARMs) are newly discovered molecules which bind to specific androgen receptors in the human body (for example bone and muscle tissue). They produce similar effects to anabolic steroids but are very specific in their action and thus not producing the various undesirable side effects associated with steroids.

In contrast to steroids, which are usually injected, SARMs are delivered orally. They provide the opportunity to design regimens that selectively target the androgen receptors in different tissues. Only the ones which are the target of the therapy will respond as they would to testosterone, while the rest of the body is unaffected. Many SARM types exist (aryl propionamides, quinolinones, bicyclic hydantoins, quinolines), though aryl propionamides such as ostarine, andarine/S-4, and S-23 are the most advanced SARMs so far.

None of the currently developed SARMs are perfectly designed for anabolic effects limited only to the muscle and bone tissue, but some come very close to it. If testosterone's anabolic to androgen effect is 1:1, there are some SARMs with the ratio of 10:1. For example, if the goal was to promote bone growth in elderly men with osteoporosis while at the same time not stimulating the testes and prostate, a SARM targeting bone and muscle tissue but with lesser activity on the prostate or testes would be far more suitable than testosterone treatment. Likewise if the goal was to stimulate libido and other sexual function in women while at the same time not causing the negative side-effects such as development of male characteristics (virilization), SARMs would be the way to do it.

SARMs have been in development since early 2000's. The first trial demonstrated effectiveness in 2003. There are currently a number of those which are of great interest to the bodybuilding community. In this article we will concentrate on S-22 Ostarine (Enobosarm).

Oral SARMs vs. Injectable steroids

An important advantage of Selective Androgen Receptor Modlators is that they are all orally active without causing liver damage, while most anabolic steroids must be injected. Those anabolic steroids which are orally active tend to cause liver damage with time. SARMs are safer in this regards.

What is Ostarine (MK-2866, S-22)?

Full chemical name: (2S)-3-(4-cyanophenoxy)-N-[4-cyano-3-(trifluoromethyl)phenyl]-2-hydroxy-2-methyl-propanamide

Ostarine is a non-steroidal selective androgen receptor modulator which binds to the androgen receptor with a Ki value of 3.8 nM. It is also known by the synonims Enobosarm, MK-2866, GTx-024 and S-22. It was developed by GTX, inc (formely under development by Merck & Co) as treatment for conditions such as muscle wasting, osteoporosis and andropause.

Ostarine in clinical trials

Enobosarm demonstrated good results in Phase I and II clinical trials (reference), increasing total lean muslce mass, enhancing strength and decreasing total tissue percent fat. Ostarine performs as a potent anabolic agent with minimal side effects on other organs (hair follicles, prostate) which are usually affected by the use of steroids.

Until now, GTx has evaluated MK-2866 in 8 clinical trials, involving 600 subjects, including three efficacy studies. A 4-month Phase II.b clinical trial enrolled 159 patients with the study confirming its primary objective of an absolute total lean body mass increase and the secondary objective increase in muscle function. (reference, reference)

Intended use of Ostarine

S22 (Ostarine) affects both muscle and bone tissue, it was developed to treat osteoporosis, andropause and reversing muscle sarcopenia in the elderly and for cachexia in cancer patients.

SARMs and Ostarine in Bodybuilding and Sports

Because SARMs have been widely used by atletes to gain an advantage in stamina, strength and physical fitness they have been banned by the World Anti-Doping Agency in January 2008. Since then, several athletes have been caught and disqualified because they tested positive to Ostarine.

Professional bodybuilders mostly use S-22 (Ostarine) in between steroid cycles to maintain the progress while off testosterone. For novices MK-2866 is a good start as it does not require injections and does not damage the liver (like oral steroids mostly do). Also there are no side effects which are usually associated with steroid use. Ostarine is used for both lean muscle gains and reducing body fat or recomping (both bulking and cutting fat at the same time).

Libido increase by Ostarine

It has been observed that Ostarine while taken in oral tablet form, significantly increases sex drive (libido). For this purpose the dose is 15mg to 30mg per day. At 30mg/day dose some people prefer to split it into 15mg in the morning and 15mg in the evening.

For some reason Ostarine dissolved in oil does not produce the same libido heightening effect as the oral tablet form. It takes about 5-7 days to notice the libido increase.

Ostarine side effects

There is a lot of conflicting information floating around on various bodybuilding forums, mainly due to sellers who push SARMs and make wild claims while on the other side people with no first hand experience making uneducated guesses. This "information" then gets perpetuated and repeated.

Most people seem to agree that natural testosterone suppression caused by Ostarine is relatively light if there is any. To counter this, people use mild PCT (for example 500mcg of HCG once per 3-4 days during and 2 weeks after the Ostarine cycle).

Bodybuilders are reporting elevated blood pressure when dosing Ostarine above 15mg per day. This is increase is temporary and goes back to normal within a few days after the S22 cycles has ended.

Actual effects of Ostarine

A seasoned bodybuilder might be dissappointed while looking for rapid bulking effects he would be accustomed to from steroid use. The steroid induced, rapidly gained volume is mostly water. To be able to trully appreciate Ostarine for what it does, give it some time and look for the strenght increase and slower muscle gain (without the watery look). Ostarine would be perfect for an UFC fighter because of the increase in muscle strength, speed and control without much added mass.

These are the observable Ostarine effects:
  • increase in overall muscle strength and performance
  • decrease in body fat
  • increase in lean muscle (without water retention)
  • increased libido (with oral tablet form)
  • increased bone density and strength
  • improved mobility in tendons, ligaments and joints
  • increased endurance

Ostarine dosage:

Ostarine has a half life of approximately 24 hours as such it is taken orally once per day. Some people prefer to split the daily dosage in half and take it in the morning and evening. Below are some Ostarine dose examples:

  • 12.5mg per day is taken as treatment for Osteophorosis
  • 12.5mg to 15mg per day for 4 - 6 weeks to help an average person get back into overal good shape
  • 12.5mg to 15mg per day for 4 - 6 weeks is commonly used by athletes during body fat cutting period while training on lower calorie diet
  • 30mg per day (either at one time or split into morning and evening dose) is taken to increase libido
  • 25mg to 30mg per day (either at one time or split into morning and evening dose) for the duration of 4 - 6 weeks is the usual protocol for lean muscle building
  • 36mg per day for the duration of 4-8 weeks is considered extreme, to be used by seasoned bodybuilders (recommended to be followed by a post testosterone cycle treatment)

GTx-024 is still an experimental drug, and should be treated as such. Athletes who choose to experiment with S-22 usually keep their cycles at 4 to 8 weeks maximum before taking time off to let the body restore it's natural hormonal balance.

Where to buy Ostarine?

There are countless online shops selling SARMs and Ostarine dissolved in oil. The oral tablets can be bought from here (see the green button below)

Buy Ostarine