Ostarine (MK-2866) is a non-steroidal agent with anabolic activity. Selective androgen receptor modulator (SARM) GTx-024 is designed to work like testosterone, thus promoting and/or maintaining libido, fertility, prostate growth, and muscle growth and strength. Mimicking testosterone's action, this agent may increase lean body mass, thereby ameliorating muscle wasting in the hypermetabolic state of cancer cachexia.

Androgen receptor:3.8 nM(Ki)

Compared to any non-steroidal androgen receptor (AR) agonists, Ostarine exhibits the highest androgenic and anabolic activity in the body, particularly affecting the prostate, seminal vesicles, and levator ani muscle, with ED50 values of 0.12, 0.39, and 0.03 mg/day, respectively. This makes it four times more effective on the levator ani muscle than testosterone propionate. At a low dose of 0.03 mg/day, Ostarine demonstrates effective and selective activity in anabolic tissues. Following a single intravenous injection of 10 mg/kg, Ostarine presents a slow decline in plasma concentration with a longer half-life of 6 hours, compared to the 2.6-4.0 hours half-life when targeting other cyan/nitro substituted Selective Androgen Receptor Modulators (SARMs). In castrated male rats, Ostarine shows significant androgenic and anabolic activity, more effectively stimulating growth in the prostate, seminal vesicles, and levator ani muscle than other cyan/nitro substituted SARMs. Ostarine facilitated recovery of prostate weight by 39.2%, seminal vesicle weight by 78.8%, and notably stimulated levator ani muscle growth beyond other male organs to 141.9%.

Ostarine (10 nM) modulates the transcriptional activity of the androgen receptor (AR) in CV-1 cells co-transfected with human androgen receptor expression vectors, luciferase reporter vectors, and β-galactosidase control vectors. Ostarine binds to the androgen receptor with the highest affinity among selective androgen receptor modulators (SARMs), exhibiting a Ki value of 3.8 nM.