Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| Cardarine (GW-501516) | S-23 | |
|---|---|---|
| Category | SARMs | SARMs |
| Standard Dose | Research indicates 10-20 mg daily orally for 8-12 weeks. Clinical trials (metabolic syndrome) used 2.5-10 mg/day. | 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, 1-2 hours before exercise for acute endurance benefit. Half-life approximately 16-24 hours. Consistent daily dosing. | Split into 2 daily doses due to relatively short half-life (~12 hours). Morning and evening dosing. |
| Cycle Duration | 8-12 week cycles. No HPG suppression, so PCT is not required. However, long-term safety is unknown and cycling is prudent. | 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 |
Cardarine is a selective peroxisome proliferator-activated receptor delta (PPARd) agonist, not a SARM (it does not bind the androgen receptor). PPARd activation in skeletal muscle upregulates genes for fatty acid oxidation (CPT1B, PDK4, ACOX1), shifting fuel substrate from glycolysis toward beta-oxidation, effectively increasing endurance capacity and fat utilization. It increases oxidative type I (slow-twitch) muscle fiber proportion, enhances mitochondrial biogenesis via PGC-1a coactivation, reduces circulating triglycerides and LDL, and increases HDL cholesterol. PPARd activation also reduces macrophage-mediated inflammation through NF-kB suppression.
Research indicates 10-20 mg daily orally for 8-12 weeks. Clinical trials (metabolic syndrome) used 2.5-10 mg/day.
Once daily, 1-2 hours before exercise for acute endurance benefit. Half-life approximately 16-24 hours. Consistent daily dosing.
8-12 week cycles. No HPG suppression, so PCT is not required. However, long-term safety is unknown and cycling is prudent.
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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