Mechanism of Action

Mechanism of Action

Ostarine attaches to proteins in the body known as androgen receptors (AR). When ostarine binds to these receptors, it tells the muscles in the body to grow. Unlike some other chemicals that bind to androgen receptors, such as steroids ostarine doesn’t seem to cause as many side effects in other parts of the body.

The AR and its endogenous ligands, androgens, are important for development and maintenance of muscle and bone, secondary sexual organs, and development of other tissues. Although androgens are important for normal development of various tissues, under certain circumstances they also promote pathology of the prostate, heart, and the liver. Risks of testosterone therapy such as dyslipidemia, benign prostatic hypertrophy, and uterine hyper-proliferation preclude its use. These pathological roles of testosterone and its 5α-reduced form (DHT) led to the search for tissue-selective agonists of the AR that could potentially activate the AR in selected tissues while sparing other tissues such as prostate, heart, and liver. Such an agonist would provide an opportunity to fully realize the therapeutic benefits of androgens. Most of the SARMs developed thus far are non-steroidal and have the ability to activate the AR in muscle and bone, without accompanying activation or minimal activation of the AR in prostate or seminal vesicles.

In a similar vein, SARM development has also sought to overcome the potential virilizing effects of steroidal androgens. Considering that females, like males, are also affected by osteoporosis, sarcopenia, and cachexia, a non-virilizing SARM could treat these pathological states in women, without the virilizing side-effects accompanying steroidal androgens. The putative beneficial effects of testosterone therapy in certain female populations appear to be outweighed by the risks of virilization and poorly characterized cardiovascular risk. Recent clinical trials, although highlighting testosterone’s ability to improve sexual function and muscle mass in older men, corroborated concerns that testosterone’s cardiac risks outweighed its therapeutic benefits.