Ostarine

Areas of active research — not promised effects

Each tag links to other compounds with research into that goal. Research use only: these are areas of study, not human-use claims.

Related by research scope · open each to compare

Ostarine/enobosarm has no FDA-approved indication and is not listed as a controlled substance under the Controlled Substances Act. It is classified as an unapproved new drug under the Food, Drug, and Cosmetic Act; marketing or selling it for human use — including as a dietary supplement or performance enhancer — is unlawful. The FDA has issued multiple warning letters to SARM vendors and explicitly states that SARMs are not legitimate dietary supplement ingredients. Research-use-only (RUO) supply to qualified laboratories occupies a regulatory grey area but does not authorise clinical or human use.

Confirmed high-severity market-integrity event (enforcement / recall / counterfeit)

Transparent blend · bci-1.0 · never paid-placement

Primary name

Ostarine

Origin

Synthetic small molecule originally developed by GTx Inc. (Memphis, TN) in the early 2000s as an investigational treatment for muscle wasting, cachexia, and osteoporosis. Also known by the INN enobosarm and the research code GTx-024. Development was subsequently continued by Veru Inc., which has advanced enobosarm into Phase 2 and Phase 3 clinical evaluation for androgen receptor-positive breast cancer subtypes and, more recently, for preservation of lean body mass in patients receiving GLP-1 receptor agonists. Enobosarm has not received regulatory marketing approval in any jurisdiction.

Registry IDs

PubChem CID

11326715

CAS

841205-47-8

InChIKey

JNGVJMBLXIUVRD-SFHVURJKSA-N

DrugBank

DB12078

ChEMBL

CHEMBL1738889

Molecular formula

C19H14F3N3O3

Molar mass

389.3 g/mol

Monoisotopic

389.09872580 Da

InChIKey

JNGVJMBLXIUVRD-SFHVURJKSA-N

Appearance

White to off-white crystalline solid

Solubility

Poorly water soluble; soluble in DMSO (~10 mg/mL), ethanol, and polyethylene gly…

Sequence not available in current seed.

Stability: Stable as dry powder under recommended conditions; susceptible to degradation on prolonged exposure to light, heat, and moisture. Reconstituted solutions should

Vial sizes

null mg

Purity grades

≥98% / ≥99%

Salt forms

Free base (primary)

• GHS hazard class on file
• PPE & spill response
• Disposal guidance
• Not-for-human-consumption posture

How much research exists, and of what maturity — never a verdict on whether it works.

Mechanism of action

• Ostarine binds the androgen receptor (AR) with high selectivity and acts as a partial agonist, promoting AR-dependent transcription of anabolic gene programmes in skeletal muscle and bone with substantially lower stimulatory activity in reproductive tissues such as the prostate and seminal vesicles
• The tissue selectivity relative to dihydrotestosterone arises from the compound's arylpropionamide scaffold, which induces a conformational change in the AR ligand-binding domain that differentially recruits coactivator proteins
• In AR-positive breast cancer cell lines, ostarine suppresses oestrogen receptor (ER)-driven transcription through AR-ER crosstalk, providing a pharmacological rationale for its investigation in ER+/AR+ and triple-negative breast cancer
• Importantly, ostarine does not undergo aromatisation to oestrogen or reduction to dihydrotestosterone, distinguishing its endocrine profile from steroidal androgens

Pharmacokinetics (ADME)

Half-life

~24 hours (range 14–24 h reported in human studies); suitable for once-daily dosing

Clearance

Metabolised via CYP3A4 and UGT pathways; co-administration with the CYP3A4 inducer rifampin reduced AUC by ~43% and Cmax by ~23%; co-administration with the UGT inhibitor probenecid extended half-life by ~78% and increased AUC ~50%; excreted predominantly in faeces (~70%) in rat models

PK–PD note: Oral bioavailability is adequate for once-daily research dosing. The primary long-term urinary metabolite used as an anti-doping marker has been characterised in human in vitro and in vivo metabolism …

Reading the evidence

• Evidence quality and gaps vary by application — see the cited grades above.
• Indexed-article counts span all evidence tiers, not only completed human trials.
• No first-party human-dosing, efficacy, or benefit claims are made here.

Key reviews & evidence-gap sources

• Palmieri et al. 2024 — Study G200802, phase 2 RCT in AR+/ER+/HER2-negative advanced breast cancer (Lancet Oncology 25(3):317–325; PMID 38342115) — NCT02463032; completed, peer-reviewed human RCT — 1 of 3 counted toward completedHumanRcts. [Verification precision: primary-endpoint clinical benefit rate at 24 weeks was 32% (16/50) at 9 mg and 29% (15/52) at 18 mg among evaluable AR-positive subjects; the full-analysis-set CBR was 25% and 27%. Randomised, open-label, two-dose parallel design (no placebo arm). A source-attributed trial finding, not a first-party human-benefit claim.]
• Dobs et al. 2013 — phase 2 RCT, cancer-related muscle wasting (Lancet Oncology 14(4):335–345) — NCT00467844; completed, published human RCT. [Verification corrected: the first pass framed this as '~1.3 kg at 3 mg vs placebo'. Per the abstract, total lean body mass increased vs BASELINE (within-group) — 1 mg median +1.5 kg (p=0.0012) and 3 mg median +1.0 kg (p=0.046), versus a non-significant +0.02 kg (p=0.88) on placebo. These are within-group change-from-baseline results, not a between-group superiority test; the 3 mg arm gained ~1.0 kg (not ~1.3 kg). A trial-level finding, not a therapeutic claim.]
• Dalton et al. 2011 — phase 2 RCT in healthy elderly men / postmenopausal women (J Cachexia Sarcopenia Muscle 2(3):153–161; PMID 22031847) — Completed, double-blind, placebo-controlled human RCT (120 enrolled / 115 completed; oral GTx-024). 3 mg significantly increased total lean body mass (DXA). ClinicalTrials.gov/EudraCT ID not located this pass — traceability rests on the peer-reviewed publication itself. A pharmacodynamic finding, not an approved-use efficacy claim.
• Hahamyan et al. 2023 — PRISMA systematic review of SARM abuse in athletes (Orthopaedic Journal of Sports Medicine) — 1382 abstracts screened, 23 studies included (2011–2022) across ostarine/ligandrol/RAD-140/andarine — the closest systematic-review anchor; not ostarine-exclusive.
• Bond et al. 2025 — 'Selective androgen receptor modulators: a critical appraisal' (Frontiers in Endocrinology 16) — Narrative critical appraisal (not a formal systematic review); concludes robust evidence of SARM superiority over steroidal androgens remains incomplete; discusses enobosarm's clinical-trial history. [Context: the enobosarm program is entirely Phase 1–2 — POWER1/POWER2 Phase 3 (NSCLC muscle wasting) did NOT meet the US pre-specified co-primary endpoints (FDA ODAC voted against approval, 2013).]

5 registered trials — 0 currently recruiting.

Phase 2
NCT06282458
Dose-Finding Study Evaluating Effect on Body Composition of Enobosarm in Patients Taking a GLP-1 for Chronic Weight Mgmt

COMPLETED

Phase 2
NCT02463032
Efficacy and Safety of GTx-024 in Patients With Estrogen Receptor (ER)+/Androgen Receptor (AR)+ Breast Cancer

COMPLETED

Phase 3
NCT04869943
Efficacy Evaluation of Enobosarm Monotherapy in Treatment of AR+/ER+/HER2- Metastatic Breast Cancer

TERMINATED

Phase 2
NCT02368691
Efficacy and Safety of GTx-024 in Patients With Androgen Receptor-Positive Triple Negative Breast Cancer (AR+ TNBC)

TERMINATED

Phase 2
NCT03241342
Study to Assess Enobosarm (GTx-024) in Postmenopausal Women With Stress Urinary Incontinence

COMPLETED

Summary (literature)

In controlled clinical trial settings at doses of 1–3 mg/day, enobosarm's most commonly reported adverse effects included headache, fatigue, nausea, back pain, and anaemia. Dose-dependent suppression of serum testosterone, sex hormone-binding globulin (SHBG), FSH, and HDL cholest…

WADA status

Prohibited in-competition and out-of-competition under the 2026 WADA Prohibited List, Section S1.2 (Other Anabolic Agents). Ostarine (enobosarm) is one of six S…

Dominant research route: Oral is the only route with any published human or animal pharmacokinetic/efficacy data for ostarine (enobosarm / MK-2866 / GTx-024 / S-22): every completed Phase 1–3 human trial and the modern rat efficacy/ADME literature dosed it orally. No subcutaneous, intramuscular, intravenous, intraperitoneal, intranasal, or topical route has been characterised in the published literature for this specific compound.

The only administration route with any published pharmacokinetic or efficacy data for ostarine. Human data span a completed Phase 1/2 program: a placebo-controlled Phase 2 RCT in 120 healthy elderly men and postmenopausal women (Dalton et al. 2011); a completed Phase 2 RCT in cancer-associated muscle wasting (Dobs et al. 2013); two Phase 3 NSCLC muscle-wasting trials (POWER1/POWER2, primary completion 2013) that did NOT meet the US pre-specified co-primary endpoints (company/conference-sourced; no peer-reviewed primary-results publication); and a Phase 2 RCT in AR+/ER+/HER2-negative advanced breast cancer (Study G200802, Lancet Oncology 2024). Rat ADME and rat efficacy models (ovariectomized/orchiectomized bone- and muscle-loss models) also dosed enobosarm orally (gavage or diet-mixed). [Verification corrected: the first pass characterised POWER1/POWER2 as having a 'mixed' co-primary split; the refute pass found that framing backwards — lean body mass improved vs placebo in BOTH trials (POWER1 p=0.0003, POWER2 p=0.0227) and the physical-function/stair-climb endpoint was met in POWER1 only (p=0.0185), so the program failed the US co-primary responder analysis overall.]

Bioavailability: A rat ADME study found absorption 'rapid and complete' with high oral bioavailability (secondary sources report ~100% in rats), attributed to minimal first-pass hepatic metabolism; rat elimination half-life ~0.6 h (male) vs ~16.4 h (female), with ~70% of an oral dose eliminated in feces within 48 h. In human Phase 1 dosing, reported elimination half-life is ~14–24 h (consistent with once-daily dosing), with a median Tmax of 1–2 h. Species-dependent pharmacology; no human dosing amount is implied.

Every completed or ongoing human trial identified for this compound dosed it orally (softgel capsule in the cited protocols); no subcutaneous, intramuscular, intravenous, intraperitoneal, intranasal, or topical route has a published pharmacokinetic or efficacy study specific to ostarine/enobosarm. Independent of the trial record, research-chemical community/vendor discourse (Layer B) also reports oral (liquid or capsule) as the near-universal practical route and counsels against injecting oral-formulated SARM material on solubility/vehicle grounds rather than any published safety data. No human dosing amount is implied.

Animal & human figures are kept visibly separate so studied animal doses are never misread as human guidance.

Sorted A–Z by vendor — never by price

Weekly median $/mg from the live vendor crawl.

Researched storefront prices, bucketed

p25 $0.060 · median $0.069 · p75 $0.097 · 12 researched vendors

Value rule: don't just buy the cheapest — a price under $3/mg is a red flag. Pair price with COA and independent-test grade.

Estimated cost of research (10 mg)

Vial (best researched price)

$1

Bacteriostatic water (generic estimate)

$6

Syringes / supplies (generic estimate)

$12

What each test proves — general guidance, plus this compound's researched purity data

Purity on the current market (researched)

No systematic independent HPLC purity-range survey specific to finished ostarine products (analogous to the peptide market's Finnrick aggregate) was found. Vendor pages commonly advertise ≥98% API purity backed by a named third-party lab (e.g. Sports Technology Labs and Chemyo cite MZ Biolabs / Colmaric Analyticals COAs), but the load-bearing independent literature measured CONTENT ACCURACY (whether the labeled dose was actually present) rather than raw purity: Van Wagoner et al. (JAMA, 2017) found only 41% (18/44) of purchased SARM-labeled products matched the label's stated active-compound amount.

Independent labs cited for this compound

No FDA product recall (Class I/II/III) specific to an ostarine product was found. As an unapproved drug sold outside the regulated supply chain, FDA action takes the form of warning letters, import detention and DOJ criminal prosecution rather than a formal recall. Reported honestly as an empty recall result, not invented.

Buyer red-flag checklist

• No batch/product-specific COA provided on request, or a COA that is generic/undated.
• COA report or task ID does not resolve in the testing lab's own public verification system (Janoshik, MZ Biolabs, Colmaric) — consistent with the 'false and fraudulent certificates of analysis' the Schuffert conviction described.
• Liquid/dropper concentration (mg/mL) has no independent lab backing — Van Wagoner et al. found measured content from roughly one-tenth to more than double the labeled amount.
• Product marketed as 'Not for Human Consumption / Research Use Only' while site copy still describes a human dose, cycle length, or benefit claim — the labeling pattern FDA warning letters repeatedly cite.
• Wrong-compound or undeclared-compound substitution: independent testing has found other SARMs, ibutamoren (MK-677), GW501516, or unlisted drugs in bottles labeled as ostarine.
• Price far below the prevailing market for the labeled mg/mL concentration (consistent with a diluted, underdosed, or non-active product).
• Vendor offers only self-reported/in-house 'testing' claims with no named independent third-party lab.

GMP vs research-grade: the chemistry (SPPS + HPLC + MS) is identical — the difference is the quality system.

Underdosing / mislabeling: Derived from Van Wagoner et al. (JAMA, Nov 28 2017): of 44 internet-purchased SARM-labeled products (ostarine among the named compounds), 11 (25%) contained the labeled compound at a different amount, 8 (18%) had no detectable labeled compound, and 4 (9%) had no active compound at all — 23/44 ≈ 52% failing to deliver the labeled active-compound content (a market-level proxy, not an ostarine-isolated assay). [Verification corrected: a distinct athlete-side signal originally attributed to a 'Dec 16 2025' USADA advisory is in fact from USADA's advisory 'Growing Evidence that Ostarine is a Risk for Athletes' POSTED JULY 25, 2017 — its 72+ High-Risk-List products containing ostarine, 19 with ostarine undeclared, are 2017-vintage figures, not a 2025 report.]

• FDA's warning letters to ostarine/SARM sellers cite the products as unapproved new drugs under FD&C Act §§505(a)/301(d) — the same 'unapproved new drug' status underlying Import Alert 66-41's generic detention-without-physical-examination (DWPE / Red List) authority. No SARM- or ostarine-specific NAMED import alert entry was found; 66-41 is the general catch-all FDA relies on for unapproved-drug shipments, not a product-specific listing — reported honestly rather than invented. (The alert does not name any particular ostarine vendor on its Red List.)66-41 (Detention Without Physical Examination of Unapproved New Drugs Promoted in the U.S.)
• An RUO label is not an import exemption — CBP judges actual intended use.
• Lyophilized powder is ambient-stable in transit; temperature control needed for > 7-day transit.
• US-warehouse vendors dodge import scrutiny — they cost more but ship more reliably.

Every item dated & sourced

Prohibited at all times (in- and out-of-competition), all sports, under WADA S1.2 'Other Anabolic Agents' (within class S1 Anabolic Agents) — ostarine (enobosarm, MK-2866) is explicitly named as an example SARM on the 2026 Prohibited List; a non-Specified Substance. SARMs have been prohibited since 2008. Because no SARM is FDA-approved for human use, a Therapeutic Use Exemption is not practically available. Ostarine is reported as the most frequently detected SARM in WADA-accredited lab testing. [Verification: the '114 athlete samples over two years' figure is attributed to a Feb 2026 analysis in The Conversation by Dr. Tom Bassindale (Sheffield Hallam) — an author-stated figure not traced to a specific WADA Anti-Doping Testing Figures table, so cited as stated, not as a primary WADA count. A first-pass '863 total SARMs AAFs 2011–2024' figure had no resolving primary source and is dropped as unverified. The 'most-detected SARM' superlative is independently corroborated (PMC11277069: ostarine the most-reported S1.2 substance, 306 AAFs 2016–2022).]

No granted patents identified in current seed. Composition-of-matter coverage is limited given the peptide's synthetic origin.

• IACUC / IRB research context
• RUO buyer responsibilities & documentation
• Veterinary / alternative-use where lawful
• Jurisdiction-aware "who may lawfully obtain"

What people discuss

Reported concerns — discussion, not established effects

Reading caveats

• SARM-community forum threads (Reddit/Bluesky-style discussion) were not independently retrievable via this pass's search tool despite likely real volume — a known indexing gap, not evidence of absence; platforms[] lists only what was directly confirmed (YouTube video content; X/news-driven doping discourse).
• High-profile anti-doping news coverage (professional-athlete positive tests) dominates search-visible discourse, likely over-weighting cautionary/negative framing relative to routine forum chatter.
• Vendor- and SEO-optimized 'best SARM' / dosage blog content is frequently indistinguishable from genuine community voice; excluded from theme/concern counts where clearly commercial.
• Vision-related side effects are sometimes casually attributed to ostarine, but the discussion itself typically self-corrects this as confusion with andarine (S-4) — not counted as a genuine ostarine-reported concern.
• Survivorship / promotional bias in transformation-style videos — users with a poor experience or early discontinuation are under-represented relative to 'gains' content.

Manually researched from youtube, x— theme weights are research estimates, not live counts; aggregated & de-identified. No individual posts, quotes, or usernames are ever shown.

Relative research / market volume — populated once the activity stream is wired

Inline tooltips for lyophilized, RUO, EU/mg, SPPS, 503A and more.

Toggle plain-language ↔ scientific in the header.

• How to read a COA
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Non-steroidal oral SARM (MK-2866/enobosarm) with Phase 2 human data in muscle wasting and breast cancer; not approved; prohibited in sport. Approximately 81 articles are indexed (literature last scanned 2026-05-29). US regulatory status: Not FDA-approved; not a scheduled controlled substance; sold only for research use. Research use only.

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