Injectable S-23 400mg vial

                                             NOT FOR HUMAN CONSUMPTION

S-23 is a highly potent, oral selective androgen receptor modulator (SARM) developed to deliver strong anabolic effects in muscle and bone with reduced stimulation of prostate and skin compared with testosterone. It binds the androgen receptor (AR) as a non-steroidal ligand, drives anabolic gene programs, and—unlike testosterone—does not aromatize to estradiol or undergo 5-α reduction. In animals, S-23 produces robust HPG-axis suppression and has been explored as a candidate for male contraception. It is not FDA/EMA-approved and is prohibited by WADA.

Additional Benefits of S-23 Now Under Investigation

2. Molecular Mechanism of Action

2.1 Receptor Pharmacodynamics

S-23 binds the androgen receptor (AR) with high affinity, induces AR nuclear translocation, and activates androgen-response elements (AREs). Co-activator recruitment in skeletal muscle and bone up-regulates mTOR/S6K and IGF-1networks, while atrogenes are suppressed. Lack of aromatization/5-α reduction contributes to tissue selectivity versus testosterone.

2.2 Down-stream Biology

3. Pharmacokinetics

• Route: Oral.

• Half-life: ~10–16 h reported in preclinical/forensic PK extrapolations; human t½ not formally established. Once-daily dosing is typical in research settings.

• Absorption: Good oral bioavailability; high plasma protein binding.

• Metabolism/Elimination: Hepatic oxidative/conjugative pathways; renal/hepatic excretion of metabolites.

• Doping detection: Long-term metabolites allow detection weeks post-exposure (urine, hair) in anti-doping labs.

4. Pre-clinical and Translational Evidence

4.1 Androgen-deficiency & Sarcopenia Models

S-23 produces dose-responsive lean-mass gains, increased specific force, and bone protection with comparatively modest prostate effects versus testosterone.

4.2 Male Contraception

Oral S-23 consistently suppresses gonadotropins, lowers sperm counts/motility, and prevents conception in controlled mating trials; fertility returns after discontinuation in rodent studies.

4.3 Orthopedics & Rehabilitation

In immobilization/ovariectomy models, S-23 improves BMD, tendon-bone interface quality, and functional recovery metrics—supporting exploration alongside resistance exercise and protein optimization.

Evidence quality note: Human data for S-23 are very limited (no completed pivotal trials). Most efficacy/safety information derives from animal studies, in vitro, and anti-doping forensics.

5. Emerging Clinical Interests

6. Safety and Tolerability

• HPG-axis suppression (prominent): Marked LH/FSH and testosterone suppression with potential libido/moodchanges; recovery may take weeks to months after cessation.

• Lipids: HDL-C reductions and possible ↑ LDL/TG; monitor cardiovascular risk.

• Hepatic: Short-term controlled data are sparse; case reports from unregulated use note ALT/AST elevations—confounded by co-ingestants and product purity.

• CV/Thrombotic risk: No outcome data; lipid shifts and androgenic milieu warrant caution.

• Dermatologic: Acne/oily skin and hair shedding reported anecdotally.

• Hematologic: Mild ↑ hematocrit possible—monitor if baseline high or in risk conditions.

• Psychoneurologic: Irritability, insomnia, anxiety occasionally described in uncontrolled settings.

• Drug interactions: Potential with agents affecting hepatic enzymes/lipids; avoid hepatotoxins and use in pregnancy.

Comparative safety matrix

7. Regulatory Landscape

• Approvals: None for any indication.

• Enforcement & sport: SARMs—including S-23—are banned by WADA (S1). Anti-doping labs frequently detect S-23 metabolites in positives and in contaminated supplements.

• Public health advisories: Regulatory bodies have issued warnings about SARM-containing “supplements” and adulteration; products often lack quality control.

8. Future Directions

• Human PoC trials for male contraception with endocrine, spermatogenesis, and recovery endpoints.

• Sarcopenia/orthopedic RCTs pairing S-23 with progressive resistance training and protein intake standardization.

• Cardio-metabolic safety programs (lipids, endothelial function, ambulatory BP).

• Hepatic safety/PK under GMP supply with metabolite mapping to inform dose selection and washout.

• Medicinal chemistry toward lipid-neutral profiles and reduced HPG suppression while maintaining anabolism.

Selected References

• Kearbey J.D., Gao W., Narayanan R., et al. Non-steroidal SARMs: pharmacology, tissue selectivity, and therapeutic prospects. Journal of Pharmacology & Experimental Therapeutics; Endocrine Reviews.

• Jones A., Chen J., et al. S-23 as a candidate oral male contraceptive: suppression of LH/FSH and reversible infertility in rats. Biology of Reproduction; Contraception.

• Dalton J.T., et al. Anabolic and anti-catabolic effects of SARMs in muscle and bone. FASEB Journal; Journal of Bone and Mineral Research.

• Evans N.A., et al. Androgen receptor activation, erythropoiesis, and cardiovascular considerations.Hematology; Circulation Research.

• Drug Testing & Analysis / WADA Laboratory Reports. Detection of S-23 and its long-term metabolites in human doping control.

• Hepatology Communications; J Clin Transl Hepatol. Case reports of liver injury related to unregulated SARM products.