Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| Ostarine (MK-2866 / Enobosarm) | SR-9009 (Stenabolic) | |
|---|---|---|
| Category | SARMs | SARMs |
| Standard Dose | Research indicates 10-25 mg daily orally for 8-12 weeks. Phase 2 clinical trials used 1-3 mg/day with significant lean mass gains. | Research indicates 20-30 mg daily orally, split into 3-4 doses due to very short half-life (~4 hours). Some users prefer sublingual administration for improved bioavailability. |
| Timing | Once daily, morning or evening. Consistent timing. Half-life approximately 24 hours. No food timing requirements. | Split into 3-4 doses throughout the day due to ~4-hour half-life. Example: 7am, 11am, 3pm, 7pm. Avoid late-night dosing as REV-ERB modulation may affect circadian rhythm and sleep. |
| Cycle Duration | 8-12 week cycles. PCT may be required depending on suppression level and cycle length. | 8-12 week cycles. No HPG suppression. Cycling recommended due to limited long-term data. |
| Evidence Level | moderate_human | animal_plus_anecdotal |
Ostarine (enobosarm/GTx-024) is a nonsteroidal selective androgen receptor modulator that binds the androgen receptor with high affinity, inducing a conformational change that recruits coactivator proteins preferentially in muscle and bone tissue over prostate and seminal vesicles. This tissue selectivity arises from differential AR cofactor recruitment and 5-alpha reductase metabolism. Ostarine promotes lean body mass by activating AR-mediated transcription of anabolic genes (MYC, IGF-1) in myocytes while minimizing androgenic effects in reproductive tissues. It has demonstrated dose-dependent increases in lean mass in Phase 2 trials.
Research indicates 10-25 mg daily orally for 8-12 weeks. Phase 2 clinical trials used 1-3 mg/day with significant lean mass gains.
Once daily, morning or evening. Consistent timing. Half-life approximately 24 hours. No food timing requirements.
8-12 week cycles. PCT may be required depending on suppression level and cycle length.
SR-9009 is a synthetic agonist of REV-ERBa and REV-ERBb, nuclear receptors that form the repressive limb of the circadian clock and regulate metabolic gene expression. REV-ERB activation represses BMAL1/CLOCK transcription, modulating circadian rhythm. In skeletal muscle, SR-9009 increases mitochondrial count and oxidative capacity by upregulating mitochondrial biogenesis genes. It enhances fatty acid and glucose oxidation, increases exercise endurance, and reduces lipogenesis in the liver. SR-9009 also reduces inflammatory gene expression via NF-kB pathway suppression. Recent research has identified significant REV-ERB-independent effects, suggesting the mechanism is more complex than initially characterized.
Research indicates 20-30 mg daily orally, split into 3-4 doses due to very short half-life (~4 hours). Some users prefer sublingual administration for improved bioavailability.
Split into 3-4 doses throughout the day due to ~4-hour half-life. Example: 7am, 11am, 3pm, 7pm. Avoid late-night dosing as REV-ERB modulation may affect circadian rhythm and sleep.
8-12 week cycles. No HPG suppression. Cycling recommended due to limited long-term data.
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