SARMs

LGD-3303

Updated · 13 sources · Editorial policy

LGD-3303 is an experimental, nonsteroidal selective androgen receptor modulator (SARM). A SARM is a drug designed to activate the androgen receptor in muscle and bone while having less effect on tissues such as the prostate. LGD-3303 was characterized by scientists at Ligand Pharmaceuticals in a small set of rat studies published in 2009 and 2010.

The most important fact about LGD-3303 is how little is known about it in people. No published human study exists, and ClinicalTrials.gov lists no registered trial. Everything known about its effects comes from rats, plus metabolism work done for horse and human doping control. It is not an approved drug anywhere, and it is banned in sport as a SARM.

This page summarizes what the animal studies and anti-doping research report. It is for education only and is not medical advice.

Property Detail
Drug class Nonsteroidal SARM (quinolinone chemical class)
Developer Ligand Pharmaceuticals (preclinical research, 2009–2010 publications)
Formula / molecular weight C₁₆H₁₄ClF₃N₂O; 342.7 g/mol
Route studied Oral (rats, horses); continuous infusion (rats)
Doses studied Animal only, e.g. 3–30 mg/kg/day orally in female rats; 0.05 mg/kg once in horses
Half-life in humans Unknown; no human pharmacokinetic data published
Human trials None published; none registered on ClinicalTrials.gov
Aromatizes to estrogen No (described as nonaromatizable)
US status Not FDA approved; not named in the DEA anabolic steroid schedule
WADA status Prohibited at all times (S1.2, SARMs)

What it is

LGD-3303’s chemical name is 9-chloro-2-ethyl-1-methyl-3-(2,2,2-trifluoroethyl)-6H-pyrrolo[3,2-f]quinolin-7-one (PubChem). It is not a steroid. Anti-doping chemists group it with LGD-2226 in the quinolinone class of SARMs (Stacchini et al., J Pharm Biomed Anal 2021). Despite the similar name, it is a different molecule from ligandrol (LGD-4033), which belongs to a separate chemical class (pyrrolidinyl-benzonitrile) in the same analysis.

In laboratory binding and gene-activation assays, LGD-3303 was a potent androgen with “little or no cross-reactivity” with related hormone receptors (Vajda et al., J Bone Miner Res 2009). A later study by researchers including a Ligand scientist described it as nonaromatizable, highly selective for the androgen receptor, and able to cross the blood-brain barrier (Kudwa et al., Endocrinology 2010).

Why it was called tissue selective

In castrated male rats, LGD-3303 had potent activity on the levator ani (a muscle used as a standard marker of anabolic activity) but acted only as a partial agonist on the prostate and preputial gland (Vajda et al., JPET 2009). The researchers tested whether this was just a matter of where the drug ends up:

  • Selectivity held whether the drug was given orally or by continuous infusion, two routes with very different blood-level patterns.
  • LGD-3303 concentrations were actually higher in the prostate than in the levator ani muscle.

The authors concluded that the selectivity comes from how LGD-3303 interacts with the androgen receptor itself, not from its distribution in the body. This is a rat finding. Whether the same muscle-over-prostate pattern occurs in people has never been tested.

Pharmacokinetics

The developer’s study describes LGD-3303 as orally available in rats (Vajda et al., JPET 2009). No human half-life, peak level or bioavailability has been published.

The only other in vivo data come from horses. Two Thoroughbreds received a single oral dose of 0.05 mg/kg (Broberg et al., J Pharm Biomed Anal 2023):

Finding in horses Result
Metabolites identified 8 (hydroxylated, one carboxylated, and glucuronide conjugates)
Parent drug detectable in plasma and urine Up to 24 h
Longest-detected metabolite A monohydroxylated metabolite (M1), up to 72 h in hydrolyzed urine
Plasma at 36 h Only M1 detected, not the parent drug

A separate in-vitro study using horse liver microsomes found four phase I metabolites of LGD-3303, mainly from hydroxylation (Cutler et al., Drug Test Anal 2022). Human liver microsomes have also been used to make LGD-3303 metabolites as reference targets for testing human urine (Stacchini et al., 2021). These studies show how the body may break the drug down, not how long it lasts in a person.

Regulatory status

  • Not an approved drug. No SARM has been approved and registered as a pharmaceutical product (Broberg et al., 2023), and SARMs have no FDA-approved use (Vasireddi et al., Am J Sports Med 2025).
  • No clinical development record. A search of ClinicalTrials.gov for LGD-3303 returns no registered studies (ClinicalTrials.gov).
  • Not a named controlled substance in the US. LGD-3303 does not appear in the DEA’s Schedule III list of anabolic steroids (21 CFR 1308.13).
  • Banned in sport. WADA prohibits SARMs at all times under S1.2 “Other anabolic agents.” LGD-3303 is not named in the list’s examples, but the class is listed as “including but not limited to” those examples (WADA 2026 Prohibited List). It is also prohibited in horse racing (Broberg et al., 2023).

What the research shows

All efficacy data come from three rat studies by the developer’s scientists and collaborators. There are no human data on muscle, strength, bone or any other outcome.

Muscle and prostate in castrated male rats

Orchidectomized (castrated) male rats were given LGD-3303 orally for 14 days (Vajda et al., J Bone Miner Res 2009):

  • the levator ani muscle grew above the weight seen in intact (non-castrated) rats;
  • the ventral prostate never exceeded 50% of intact weight, even at high doses.

The pharmacokinetic study confirmed that the prostate was never stimulated above intact levels as blood concentrations rose (Vajda et al., JPET 2009).

Bone in a rat model of osteoporosis

In ovariectomized female rats, a standard model of postmenopausal bone loss, LGD-3303 was compared with alendronate (an osteoporosis drug) and with the combination (Vajda et al., J Bone Miner Res 2009). The abstract reports that LGD-3303:

  • increased muscle weight in the female rats;
  • increased bone mineral density and content at both cortical (outer, dense) and cancellous (inner, spongy) bone sites;
  • had anabolic (bone-building) effects on cortical bone, partly on the outer (periosteal) surface, that were not seen with the bisphosphonate.

The combination was at least as effective as either drug alone at every site measured, and in some cases significantly better. The authors proposed it as a possible therapy for osteoporosis and frailty, but no human study followed.

Sexual behavior in female rats

Gonadectomized female rats received LGD-3303 at 3–30 mg/kg by daily oral gavage (Kudwa et al., Endocrinology 2010). The results depended on prior experience:

  • In sexually experienced females, it increased preference for males after 1 or 7 days. The androgen receptor blocker flutamide prevented this effect.
  • In sexually naive females, it reduced preference for males.
  • With low-dose estrogen and progesterone priming, it increased mating behaviors.

The authors suggested a possible use in women with low sexual desire. This was never tested in humans.

Side effects and risks

No human safety data

Because LGD-3303 has never been studied in people, its side effects in humans are unknown. A 2023 systematic review of SARM safety in healthy adults found 18 clinical trials and 15 case reports across several SARMs, and none involved LGD-3303 (Vignali et al., J Xenobiot 2023). Claims that it is “safe” or “non-suppressive” have no human evidence behind them.

What is known about SARMs as a class

The class-level evidence comes from other SARMs and cannot be assumed to apply to LGD-3303 in detail. Still, it is the best available signal:

  • Liver. The 2023 review found 15 case reports of drug-induced liver injury in SARM users, and elevated ALT (a liver enzyme) in a mean of 7.1% of SARM-exposed participants across trials (Vignali et al., 2023).
  • Other reported harms. The same review found one case report each of Achilles tendon rupture and rhabdomyolysis (muscle breakdown), plus two rhabdomyolysis cases in a trial of another SARM, GSK2881078.
  • Hormones and metabolism. A 2025 systematic review lists testosterone suppression, impaired insulin sensitivity, cardiovascular events and tendon damage among reported SARM effects (Vasireddi et al., 2025). No study has measured hormone suppression with LGD-3303 in humans.

Product quality

LGD-3303 is not available as a regulated medicine, so anything sold under the name is unregulated. When researchers bought 44 products sold online as SARMs, only 52% contained a SARM at all, 25% contained substances not on the label, and only 41% matched their labeled amount (Van Wagoner et al., JAMA 2017). The SARMs actually found were ostarine, LGD-4033 and andarine, not LGD-3303, so these figures describe the SARM market in general.

Drug testing

Anti-doping laboratories have validated urine methods that include LGD-3303 and its metabolites, with screening detection capability of 0.1–1.0 ng/mL across the SARMs tested (Stacchini et al., 2021).

Key takeaways

  • An experimental compound only. LGD-3303 is a nonsteroidal SARM that never progressed to published human trials or approval.
  • Rat data showed selectivity. In castrated rats it built the levator ani muscle above normal while keeping the prostate below 50% of normal weight.
  • Bone effects in animals. It increased bone density and built new outer bone in a rat osteoporosis model, with added benefit alongside alendronate.
  • Human dose, half-life and safety are unknown. No human pharmacokinetic or safety data exist, so any claimed dose or “mild” profile is unsupported.
  • Prohibited in sport and unregulated. WADA bans SARMs at all times, labs can detect LGD-3303 and its metabolites, and online SARM products are often mislabeled.

Sources

  1. Vajda EG, Hogue A, Griffiths KN, et al. Combination treatment with a selective androgen receptor modulator q(SARM) and a bisphosphonate has additive effects in osteopenic female rats. J Bone Miner Res. 2009;24(2):231–240. PubMed.
  2. Vajda EG, López FJ, Rix P, et al. Pharmacokinetics and pharmacodynamics of LGD-3303 [9-chloro-2-ethyl-1-methyl-3-(2,2,2-trifluoroethyl)-3H-pyrrolo-[3,2-f]quinolin-7(6H)-one], an orally available nonsteroidal-selective androgen receptor modulator. J Pharmacol Exp Ther. 2009;328(2):663–670. PubMed.
  3. Kudwa AE, López FJ, McGivern RF, Handa RJ. A selective androgen receptor modulator enhances male-directed sexual preference, proceptive behavior, and lordosis behavior in sexually experienced, but not sexually naive, female rats. Endocrinology. 2010;151(6):2659–2668. PubMed.
  4. National Center for Biotechnology Information. LGD-3303, PubChem CID 25195253. PubChem.
  5. Broberg MN, Knych H, Bondesson U, et al. Equine in vivo metabolite profiling of the selective androgen receptor modulator LGD-3303 for doping control. J Pharm Biomed Anal. 2023;233:115468. PubMed.
  6. Cutler C, Viljanto M, Taylor P, et al. Identification of equine in vitro metabolites of seven non-steroidal selective androgen receptor modulators for doping control purposes. Drug Test Anal. 2022;14(2):349–370. PubMed.
  7. Stacchini C, Botrè F, Comunità F, et al. Simultaneous detection of different chemical classes of selective androgen receptor modulators in urine by liquid chromatography-mass spectrometry-based techniques. J Pharm Biomed Anal. 2021;195:113849. PubMed.
  8. Vignali JD, Pak KC, Beverley HR, et al. Systematic review of safety of selective androgen receptor modulators in healthy adults: implications for recreational users. J Xenobiot. 2023;13(2):218–236. PubMed.
  9. Vasireddi N, Hahamyan HA, Gould HP, et al. Athlete selective androgen receptor modulators abuse: a systematic review. Am J Sports Med. 2025;53(4):999–1009. PubMed.
  10. Van Wagoner RM, Eichner A, Bhasin S, Deuster PA, Eichner D. Chemical composition and labeling of substances marketed as selective androgen receptor modulators and sold via the internet. JAMA. 2017;318(20):2004–2010. PubMed.
  11. World Anti-Doping Agency. The 2026 Prohibited List, in effect from January 1, 2026. WADA 2026 Prohibited List.
  12. US Code of Federal Regulations. 21 CFR 1308.13, Schedule III. 21 CFR 1308.13.
  13. US National Library of Medicine. ClinicalTrials.gov search for “LGD-3303” (no registered studies as of October 2026). ClinicalTrials.gov.