Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| S-23 | SR-9009 (Stenabolic) | |
|---|---|---|
| Category | SARMs | SARMs |
| Standard Dose | Research indicates 10-25 mg daily orally for 8-12 weeks. No human clinical trials — dosing extrapolated from rat pharmacology and anecdotal reports. | 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 | Split into 2 daily doses due to relatively short half-life (~12 hours). Morning and evening dosing. | 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 week cycles maximum recommended. PCT is absolutely mandatory due to profound HPG suppression. Allow full recovery before considering subsequent cycles. | 8-12 week cycles. No HPG suppression. Cycling recommended due to limited long-term data. |
| Evidence Level | animal_plus_anecdotal | animal_plus_anecdotal |
S-23 is one of the most potent nonsteroidal SARMs developed, originally investigated by GTx, Inc. as a potential male hormonal contraceptive. It binds the androgen receptor with very high affinity, producing near-steroidal anabolic effects in muscle and bone while profoundly suppressing FSH and LH, leading to oligospermia and azoospermia in animal models. S-23 increases lean body mass and bone mineral density while reducing fat mass in a dose-dependent manner. The contraceptive effect was fully reversible in rat studies — spermatogenesis and fertility recovered completely after a 100-day washout period.
Research indicates 10-25 mg daily orally for 8-12 weeks. No human clinical trials — dosing extrapolated from rat pharmacology and anecdotal reports.
Split into 2 daily doses due to relatively short half-life (~12 hours). Morning and evening dosing.
8 week cycles maximum recommended. PCT is absolutely mandatory due to profound HPG suppression. Allow full recovery before considering subsequent cycles.
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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