MK-2866 also known as Ostarine is the most researched and most widely used SARM available. It was developed and researched by GTx laboratories as a potential therapeutic aid to prevent cancer-related muscle wasting .
Ostarine binds selectively to androgen receptors in muscle, connective tissue, and bone while avoiding receptors in the hair and prostate. Androgen receptors are programmed to receive information about steroidal hormones like testosterone and DHT . By stimulating these receptors, Ostarine mimics the action of exogenous testosterone on muscles without the visible androgenic side effects of taking testosterone like hair loss or prostate growth. By 2007, Ostarine was in a Phase II clinical trial .
In 2011 a double-blind, placebo controlled phase II trial focusing on elderly men and postmenopausal women showed statistically significant improvements in lean body mass, connective tissue health, and physical function with no significant adverse effects typical to steroids. Subjects also did not display the type of bloating and oedema that is common with growth hormone or growth-hormone producing therapies .
Ostarine gained popularity with athletes quickly after it was developed. In 2013 cyclist Nikita Novikov tested positive , in 2015 Ethiopian Chatlu Beji tested positive , in 2016 Romanian-canadian professional boxer Lucian Bute , Russian heavyweight boxer Alexandre Povetkin , Austrian triathlete Lisa Marangon all tested positive for Ostarine. In 2017 American triathlete Beth Gerdes , UFC light heavyweight Tom Lawlor , and UFC fighter Tim Means all tested positive . And in 2019 MLB pitcher Frankie Montas and NFL's Taylor Lewan all tested positive for Ostarine [11,12].
MK2866 Investigational Benefits Summary:
1. Builds lean body mass without androgenic or estrogenic side effects or oedema
2. Most widely studied SARM
3. Accelerates healing of muscle, bone, and connective tissue
4. Minimal risk of virilization in female subjects
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2. Nagle, Mike (7 November 2007). "Merck flexes muscle with GTx deal". Outsourcing Pharma.
3. Dalton, James T.; Barnette, Kester G.; Bohl, Casey E.; Hancock, Michael L.; Rodriguez, Domingo; Dodson, Shontelle T.; Morton, Ronald A.; Steiner, Mitchell S. (September 2011). "The selective androgen receptor modulator GTx-024 (enobosarm) improves lean body mass and physical function in healthy elderly men and postmenopausal women: results of a double-blind, placebo-controlled phase II trial". Journal of Cachexia, Sarcopenia and Muscle. 2 (3): 153–161. doi:10.1007/s13539-011-0034-6. PMC 3177038. PMID 22031847.
7. Russian boxer Povetkin tests positive, fight with Canadian Stiverne cancelled – WBC". RT International. Retrieved 2016-12-17.
11. "Oakland A's starter Frankie Montas hit with 80-game PED suspension". USA Today. June 21, 2019. Retrieved June 21, 2019.
12. Bieler, Des (25 July 2019). "Failed PED test has a highly paid offensive lineman sharing polygraph results". Washington Post. Retrieved 25 July 2019. One of the NFL’s highest-paid offensive linemen claimed Wednesday that he did not knowingly take a banned substance he says got him a four-game suspension — and he took a polygraph test in an attempt to prove it.