What is Ostarine?
Ostarine (MK-2866) is the most extensively researched selective androgen receptor modulator (SARM). It was developed by GTx Inc. for muscle wasting and osteoporosis. It has completed Phase II clinical trials and is the SARM with the most human safety data. It is widely used for muscle preservation during caloric deficits, injury recovery, and as a mild anabolic.
Mechanism of Action
Ostarine selectively binds to androgen receptors in muscle and bone tissue with high affinity, activating anabolic signaling (protein synthesis, nitrogen retention) without significant activation of androgen receptors in the prostate, skin, or liver. This tissue selectivity is what distinguishes SARMs from anabolic steroids.
Ostarine Dosing Protocol
10–25 mg/day oral. For muscle preservation/cutting: 10–15 mg/day. For lean bulking: 20–25 mg/day. Cycle: 8–12 weeks. PCT (post-cycle therapy) may be needed at higher doses — monitor testosterone levels.
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Ostarine Benefits
Side Effect Profile
Mild testosterone suppression at higher doses (20–25 mg/day), mild liver enzyme elevation (monitor), potential lipid changes. Significantly safer than anabolic steroids. PCT may be needed after longer/higher-dose cycles.
Ostarine Stacking Guide
Ostarine works synergistically with these compounds. Click any to learn more, or ask PepBot to build you a complete stack.
Research & Citations
Frequently Asked Questions about Ostarine
Does Ostarine require PCT?
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