Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| RAD-140 (Testolone) | S-23 | |
|---|---|---|
| Category | SARMs | SARMs |
| Standard Dose | Research indicates 10-20 mg daily orally for 8-12 weeks. Phase 1 clinical trial (oncology) identified 100 mg as the maximum tolerated dose. | Research indicates 10-25 mg daily orally for 8-12 weeks. No human clinical trials — dosing extrapolated from rat pharmacology and anecdotal reports. |
| Timing | Once daily, consistent timing. Very long half-life (~60 hours) means stable plasma levels even with once-daily dosing. Morning preferred. | Split into 2 daily doses due to relatively short half-life (~12 hours). Morning and evening dosing. |
| Cycle Duration | 8-12 week cycles. PCT mandatory due to significant HPG axis suppression. | 8 week cycles maximum recommended. PCT is absolutely mandatory due to profound HPG suppression. Allow full recovery before considering subsequent cycles. |
| Evidence Level | animal_plus_anecdotal | animal_plus_anecdotal |
RAD-140 is a potent nonsteroidal SARM with high oral bioavailability and selectivity for muscle and bone AR over prostate. It acts as a full agonist at the AR in muscle tissue, promoting nitrogen retention and protein synthesis via mTOR/p70S6K pathway activation. RAD-140 also demonstrates neuroprotective properties, acting against beta-amyloid-induced neurotoxicity through AR-mediated MAPK/ERK signaling. Preclinical data show greater anabolic potency than testosterone propionate at equivalent doses with significantly reduced prostate stimulation.
Research indicates 10-20 mg daily orally for 8-12 weeks. Phase 1 clinical trial (oncology) identified 100 mg as the maximum tolerated dose.
Once daily, consistent timing. Very long half-life (~60 hours) means stable plasma levels even with once-daily dosing. Morning preferred.
8-12 week cycles. PCT mandatory due to significant HPG axis suppression.
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.
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