S-23

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evidence score

sarm

Research Only

S23GTx-023

S-23 is an arylpropionamide SARM developed by GTx Inc. with the highest binding affinity to the androgen receptor of any SARM studied. It produces near-steroid-level anabolic effects (lean mass, strength, bone density) while being orally bioavailable and potentially more selective than traditional anabolic steroids. Originally studied as a male hormonal contraceptive — it suppresses LH and FSH enough to suppress spermatogenesis in animal models. The trade-off for its potency is the highest suppression of the HPG axis among SARMs, approaching or equaling testosterone's suppressive effects. Requires rigorous PCT. No human clinical trials published; pharmacology data from animal studies only.

Evidence

No score yet

Safety

Unknown safety profile

Clinical Status

No formal phase listed

Research Sync

Not synced yet

Dosing

Typical

20 mg

10 mgRange30 mg

Frequencydaily (split 2x/day)

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Pharmacology

Half-life~11-12 hours

OnsetAnabolic effects 2-4 weeks; full effects 6-8 weeks

DurationEffects present during use; recovery requires PCT

Routes

oral

Evidence Score

—

0 studies indexed

Scoring Factors

Volume(40%)—

Quality(30%)—

Sample Size(10%)—

Consistency(10%)—

Replication(5%)—

Recency(5%)—

Evidence Levels

AScore ≥75 with at least 1 meta-analysis and 3+ RCTs

BScore ≥50 with at least 1 RCT or meta-analysis

CScore ≥25 — observational or animal evidence only

DScore <25 — very limited or preclinical data

Plain-English Snapshot

S-23 is currently categorized as a sarm compound.

Evidence scoring has not been fully computed yet, so interpret this profile as preliminary.

Safety scoring is incomplete. Start conservatively and monitor carefully.

Core mechanism

Full agonist at AR in muscle and bone; near-complete LH/FSH suppression via hypothalamic/pituitary AR activation; partial agonist in prostate; no aromatization

Practical Context

Strongest current signals

No indexed study summaries yet.

Elevated caution signals

1 severe/high side effect flag