Section 1 of 9Overview
Overview
Andarine (development code S-4 or GTx-007, also called androxolutamide) is an investigational nonsteroidal selective androgen receptor modulator (SARM). Chemically it is a small-molecule arylpropionamide bearing a nitro group — it is NOT a peptide and NOT an approved medicine. It appears on this peptide reference because it is frequently discussed and stacked alongside peptides in the fitness and "research chemical" community, not because it is one.
Andarine was developed by GTx, Inc. and is widely regarded as likely the first SARM to enter human clinical testing. Its human evidence is limited to a small, early, pre-registry Phase 1 program (about three studies, roughly 86 healthy volunteers, around 2003–2004). A planned Phase 2 (2004) never proceeded, and the program was ultimately abandoned.
Not approved — abandoned over a visual side effect
Andarine is not approved by any regulator (FDA, EMA, or otherwise) for any use. Its development was discontinued after Phase 1 because of a dose-dependent visual disturbance — a yellow/amber tint to vision and impaired adaptation to darkness (poor night/low-light vision). The effect was reversible on stopping the drug and is commonly attributed to androgen-receptor activity in ocular tissue (retina/lens), though the precise mechanism is not established in these sources. It survives only as an unregulated black-market / "research chemical" product. It is also prohibited in sport by WADA at all times. This page is educational and is not medical advice; nothing here endorses or guides human use.
Section 2 of 9Chemistry and structure
Chemistry and structure
Andarine is a nonsteroidal arylpropionamide small molecule, not an amino-acid chain. Its full chemical name is S-3-(4-acetylamino-phenoxy)-2-hydroxy-2-methyl-N-(4-nitro- 3-trifluoromethyl-phenyl)-propionamide — note the nitro (4-nitro) group in its structure.
| Property | Value |
|---|---|
| Name | Andarine (S-4 / GTx-007) |
| Class | Nonsteroidal selective androgen receptor modulator (arylpropionamide) — not a peptide |
| Molecular formula | C19H18F3N3O6 |
| Molecular weight | 441.4 g/mol (PubChem CID 9824562) |
| CAS number | 401900-40-1 |
| Route | Orally active |
Section 3 of 9Mechanism of action
Mechanism of action
- Androgen receptor (AR) partial agonist. Andarine binds the androgen receptor and acts as a tissue-selective partial agonist. The SARM design goal is to drive the anabolic program in muscle and bone while producing less stimulation of androgen-sensitive reproductive tissue (e.g., the prostate) than testosterone — attributed to different receptor conformations and cofactor recruitment. [In vitro]
- Anabolic effects on muscle and bone. In castrated (orchidectomized) male rats, andarine restored skeletal-muscle mass and strength and helped preserve bone, with a weaker effect on the prostate than dihydrotestosterone. [Animal]
- Retinal / ocular effect (the abandonment signal). The dose-dependent yellow- tinted vision and impaired night vision seen in humans is commonly attributed to androgen-receptor activity in ocular tissue (retina/lens); the exact mechanism is not established in these sources. The disturbance was reversible when the drug was stopped. [Human] observation; [Hypothesis] mechanism.
Section 4 of 9Research and evidence
Research and evidence
| Finding | Model | Source |
|---|---|---|
| S-4 (3 or 10 mg/kg for 8 weeks) restored soleus muscle mass and strength and levator ani muscle mass in castrated rats, with less prostate stimulation than DHT — an anabolic, tissue-selective profile | [Animal] — orchidectomized male rats | Gao W, Reiser PJ, Coss CC, et al. (Dalton JT). Endocrinology 2005 (PMID 16099859) |
| Andarine was among the first SARMs taken into human testing (~3 Phase 1 studies, ~86 volunteers, ~2003–2004); a planned Phase 2 (2004) did not proceed and development was abandoned | [Human] — early-phase, pre-registry Phase 1 | GTx program; summarized in review/analytical literature (Starcevic et al., PMID 23427117) |
| A dose-dependent, reversible visual disturbance (yellow/amber vision tint, impaired night vision) led to abandonment; commonly attributed to androgen-receptor activity in ocular tissue, though the exact mechanism is not established in these sources | [Human] observation — Phase 1 | GTx program; summarized in review/analytical literature (Starcevic et al., PMID 23427117) |
Human evidence in context. Human data are limited to a small, early Phase 1 program from roughly two decades ago. Because these were pre-registry studies (before ClinicalTrials.gov registration was routine), they are cited by PMID, not by an NCT number. There are no completed, published human trials establishing andarine's efficacy for muscle growth, fat loss, athletic performance, or any medical indication. The anabolic muscle/bone claims rest on animal work. Human pharmacokinetics (bioavailability, half-life) were not found in these sources.
Section 5 of 9Status and regulation
Status and regulation
- Regulatory approval: None. Andarine is not approved by the FDA, the EMA, or any other regulator for any indication. Its development was abandoned after Phase 1 because of the visual disturbance described above; a planned Phase 2 in 2004 never proceeded.
- Anti-doping: Prohibited by the World Anti-Doping Agency (WADA) at all times (in- and out-of-competition), classified under Anabolic Agents — Other Anabolic Agents (S1.2), where andarine is explicitly named alongside other SARMs (per USADA's summary of the Prohibited List). WADA sport-eligibility is a separate axis from legality.
- Market reality: It is sold only as a "research chemical" and circulates on the black market despite never having been approved. Such products are of unknown identity, purity, and potency (see Safety, below).
Section 6 of 9Safety
Safety
Visual disturbance, plus class-wide SARM signals
The defining, drug-specific safety issue for andarine is the dose-dependent visual disturbance — a yellow/amber tint to vision and impaired night/low-light adaptation — that halted its development. It was reversible on discontinuation and is commonly attributed to androgen-receptor activity in ocular tissue (retina/lens), though the exact mechanism is not established in these sources. [Human] observation.
Beyond that, class-wide SARM safety signals apply. The FDA has warned that SARM-containing bodybuilding products carry risks of liver injury, including acute liver failure, and are associated with increased risk of heart attack and stroke; SARMs also cause testosterone / HPTA suppression (reduced natural testosterone, testicular effects). SARMs sold as "supplements" are unapproved drugs, not dietary supplements. [Human]
Contamination reality — a label is not the contents
Products sold as "SARMs" frequently do not contain what the label claims. In an analysis of 44 products sold as SARMs (Van Wagoner et al., JAMA 2017;318(20):2004–2010, PMID 29183075), only 52% actually contained the labeled SARM, 39% contained a different unapproved drug, and 9% contained no active compound at all. The word "SARM" on a label is not a reliable statement of contents — identity, dose, and purity are unknown for black-market material.
The overall picture: andarine has a known, drug-specific ocular signal, sits within a drug class the FDA has flagged for liver injury and other serious harms, and — as an unregulated research chemical — carries the additional, separate hazards of contamination and mislabeling.
Section 7 of 9Legal status
Legal status
Legality not assessed here
This page does not assess the legality of buying or possessing andarine in any specific country. What is documented: it is not an approved medicine, supplement, or food ingredient anywhere, it is sold only as a research reagent, and it is not legal to sell for human consumption. A compound like this becomes an unauthorised medicine the moment it is intended for human use. Separately, it is prohibited in sport by WADA at all times (S1.2). "Research chemical" status is a legal and safety gray zone — it is not a signal of safety or approval. This is not legal advice; check your own jurisdiction.
Section 8 of 9How it compares
How it compares
Andarine is often grouped with other SARMs and "recomposition" research chemicals, but each has its own distinct profile and none is an approved physique/performance drug:
- Cardarine (GW-501516) — frequently sold and stacked alongside SARMs, but it is not a SARM: it is a PPARδ agonist whose development was abandoned over a rodent cancer signal. Different receptor, different defining hazard.
The honest framing: andarine is an abandoned, unapproved research reagent with a documented visual side effect and class-wide FDA-flagged risks — it is not a "milder, safer, or legal alternative to steroids." See the muscle growth & hormone overview.
Section 9 of 9Common misconceptions
Common misconceptions
- "Andarine is a peptide." No. It is a nonsteroidal arylpropionamide small molecule (C19H18F3N3O6, 441.4 g/mol) with a nitro group. It is covered here only because it is discussed and stacked with peptides.
- "SARMs like andarine are a safe, legal alternative to steroids." No. Andarine is not approved, was abandoned over a visual side effect, and its drug class is FDA-flagged for liver injury and testosterone suppression. It is prohibited in sport and sold only as an unregulated research chemical.
- "The vision problem is minor / permanent damage." The disturbance was dose-dependent and reported as reversible on stopping — but it was serious enough to end the drug's development. That it reverses does not make it trivial.
- "If it's labeled andarine, that's what's in it." Not reliably. In the JAMA 2017 analysis, only about half of products sold as SARMs contained the labeled compound; many contained a different drug or nothing active.
This entry is educational and summarizes published research and public regulatory information. It is not medical advice, a recommendation, or a guide to obtaining or using any substance. Not legal advice — check your own jurisdiction. Last reviewed 2026-07-10.