S-101479

Overview

S-101479 (also written S 101479 or S101479) is a nonsteroidal selective androgen receptor modulator (SARM) — a synthetic small molecule of the tetrahydro/pyrrolo[3,2-c]quinoline chemical class that binds the androgen receptor (AR). It is NOT a peptide (it is not an amino-acid chain) and NOT an anabolic steroid (its scaffold is nonsteroidal). It was developed by KAKEN Pharmaceutical Co., Ltd. (Kyoto/Tokyo, Japan).

Unlike most muscle-market SARMs, S-101479 was investigated as a candidate bone-anabolic treatment for osteoporosis rather than a body-building compound. Its entire evidence base is preclinical: ovariectomized-rat models and in-vitro cell/molecular studies. A literature and ClinicalTrials.gov search found no human clinical trials of S-101479 (0 trials), and the program appears dormant or discontinued (not confirmed in sources reviewed). It is not an approved medicine anywhere, for any indication.

Chemistry and structure

S-101479 is a nonsteroidal small molecule — an amino-acid chain it is not.

Mechanism of action

• Nonsteroidal AR ligand. S-101479 preferentially binds the androgen receptor with nanomolar affinity among nuclear receptors, as a small-molecule ligand rather than a steroid or peptide (PMID 23449329). [In vitro]
• Biased / tissue-selective agonist. In osteoblastic (bone) cells it drives AR-dependent transcriptional activity and alkaline phosphatase activity comparably to dihydrotestosterone (DHT), yet it induces very low AR homodimerization (~34.4% of DHT) (PMID 23449329). [In vitro]
• Non-canonical coactivator recruitment. It fails to recruit the canonical p160 coactivators SRC1, TIF2 and NCoA3, instead recruiting the non-canonical partners gelsolin and PROX1 — the proposed molecular basis for its tissue selectivity (PMID 23449329). [In vitro]
• Bone-anabolic with androgenic-tissue sparing. In ovariectomized rats it increased femoral bone mineral density/content while diminishing effects on the uterus and clitoral gland relative to a non-selective androgen (PMID 22791158). [Animal]
• Additive with other bone drugs. In osteoporotic female rats it produced additive bone effects when combined with a bisphosphonate, a SERM, or parathyroid hormone (PMID 22791158). [Animal]

Research and evidence

The evidence base for S-101479 is entirely preclinical — animal and in-vitro only. The highest development stage located is preclinical, and no human clinical trials were found (0 trials on ClinicalTrials.gov or in the literature).

Honest read of the evidence. The two peer-reviewed papers (PMID 22791158, PMID 23449329) are genuine preclinical work describing a bone-selective SARM mechanism and bone-density gains in rats, plus a molecular model for its tissue selectivity in cells. None of this has been validated in humans. There is no human efficacy, no human safety, and no human pharmacokinetics for S-101479. Any framing that implies human benefit is unsupported.

Status and regulation

• Not approved anywhere. S-101479 is not an approved drug in the United States, the EU, Japan, or elsewhere, for osteoporosis or any other indication. It is an unapproved investigational/research compound.
• Highest located stage: preclinical. Only ovariectomized-rat and in-vitro studies were found; no human trials are registered or published. The program appears dormant or discontinued (not confirmed in sources reviewed).
• WADA status (separate axis). Like all SARMs, S-101479 is prohibited in sport at all times, in and out of competition, under WADA S1.2 (Anabolic Agents — Other Anabolic Agents, SARMs). Anti-doping status is a separate axis from legality.

Safety

There is essentially no compound-specific human safety data for S-101479 — it has never been tested in humans. Every safety statement below is either class-level (from marketed/illicit SARM products) or from animal/in-vitro work, tagged accordingly.

• No compound-specific human safety data [Hypothesis]. S-101479 has no clinical safety, tolerability, or pharmacokinetic data. All human-risk inference is class-based or extrapolated from animal/in-vitro studies (literature search — no human studies found).
• SARM-class hepatotoxicity / drug-induced liver injury (DILI) [Human]. The FDA has warned that products containing SARMs have caused liver injury, including acute liver failure requiring hospitalization. This is a class-level signal from marketed/illicit SARM products — not measured for S-101479 specifically (FDA consumer warning on SARMs).
• Testosterone / HPTA suppression [Hypothesis]. As androgen-receptor agonists, SARMs as a class suppress the hypothalamic-pituitary-testicular axis and endogenous testosterone, with reported effects including testicular shrinkage and infertility. This has not been measured for S-101479 in humans (FDA/USADA SARM class information).
• Broader SARM-class adverse effects [Human]. The FDA has linked SARM-containing bodybuilding products to increased risk of heart attack and stroke, psychosis, sleep disturbance and sexual dysfunction. Class-level, not S-101479-specific (FDA consumer warning on SARMs).
• Not an approved medicine [Human]. S-101479 is not approved by the FDA, EMA, or any regulator; it is an unapproved investigational/research compound and not a dietary supplement. It must not be framed as a safer, milder, or legal alternative to anabolic steroids (FDA SARM regulatory status).

The contamination reality. In a landmark analysis, Van Wagoner et al. (JAMA 2017;318(20):2004-2010, PMID 29183075) chemically tested products sold as SARMs: only 52% actually contained the labeled SARM, 39% contained a different unapproved drug, and 9% contained no active compound at all. A "SARM" label — including one reading "S-101479" — is not a reliable statement of contents; the product a consumer buys may not be S-101479 at all.

Legal status

How it compares

S-101479 belongs to the same nonsteroidal SARM family as several better-known research compounds — all androgen receptor modulators, none an approved medicine, all prohibited under WADA S1.2:

• Ostarine (MK-2866) — the most-studied SARM, and the one most often found as a contaminant in mislabelled products.
• OPK-88004 — another SARM developed for a non-muscle indication (benign prostatic hyperplasia), which — unlike S-101479 — actually reached Phase 2 in humans.

What sets S-101479 apart is how early it is: it was developed for bone (osteoporosis) rather than muscle, and its evidence never left the preclinical stage — rat and in-vitro only, with no human trials at all. See the Muscle, growth & hormones overview.

Common misconceptions

• "S-101479 is a peptide." No. It is a nonsteroidal small molecule (C26H24F2N4O3, 478.5 g/mol, tetrahydro/pyrrolo[3,2-c]quinoline class), not a peptide.
• "It was developed by Astellas." No. S-101479 was developed by KAKEN Pharmaceutical (Japan).
• "It's a proven osteoporosis drug / bone-builder." No. Its bone effects are shown only in rats and cells. There are no human trials and no approval for any indication.
• "It's a safer, legal steroid." No. It is an unapproved preclinical research compound with no human safety data, it inherits SARM-class liver and testosterone- suppression risks, and it is banned in sport (WADA S1.2).
• "A specific dose gives a specific effect." There is no human dosing data of any kind for S-101479 — no half-life, no bioavailability, no route. Any dose figure quoted for humans is fabricated.

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This entry is educational and summarizes published research and public regulatory information as of the "updated" date above. It is not medical advice, not legal advice, a recommendation, or a guide to obtaining or using any substance.