LGD-3303

LGD-3303 has detailed rat evidence for androgen-receptor activity, muscle growth and bone effects. Tissue selectivity held across different exposure patterns in those experiments. Human muscle gain, PK, endocrine recovery and safety remain unverified.

preclinical nonsteroidal selective androgen-receptor modulator

Also written LGD3303 or LGD 3303
Pyrroloquinolinone SARM, distinct from LGD-4033 and LGD-2226
Published PK is from rats and horses, not humans
WADA's SARM class prohibition applies in 2026

Is LGD-3303 the same compound as ligandrol?

LGD-3303 is a separate pyrroloquinolinone SARM with formula C16H14ClF3N2O and its own preclinical record. LGD-4033, also called ligandrol, and LGD-2226 are different molecules with different evidence.

PubChem · LGD-3303 identity

Official chemical identity record

National Center for Biotechnology Information. PubChem CID 25195253.

The record identifies LGD-3303 with formula C16H14ClF3N2O, molecular weight 342.74 g/mol, CAS 917891-35-1, and UNII 7N4E1X2RJM.

Study design: Chemical database record

Identity is not approval or retail-product authentication.

Read the original source

Vajda et al. · rat PK/PD

Controlled preclinical pharmacology study

Vajda EG, López FJ, Rix P, Hill R, Chen Y, Lee KJ, O'Brien Z, Chang WY, Meglasson MD, Lee YH. Journal of Pharmacology and Experimental Therapeutics. 2009;328(2):663-670. DOI 10.1124/jpet.108.146811.

LGD-3303 prevented levator-ani loss and at higher exposures exceeded intact muscle weight. Prostate response was reduced but could approach intact weight at high exposure. Selectivity persisted across oral and infusion exposure despite higher prostate concentrations. Elevated LH declined at higher exposures. Day-14 rat Tmax was 0.7 to 2.8 hours and terminal half-life 4.3 to 8.7 hours; neither is human PK.

Participants / model: Castrated male Sprague-Dawley rats, generally five per group; tissue distribution three per time point
Treatment: Oral or continuously infused LGD-3303 across exposure groups
Follow-up: 14-day rat oral/infusion experiments
Study design: Controlled PK/PD animal study
Funding: Ligand Pharmaceuticals-associated study

The concentration-time and tissue data are rat pharmacokinetics, not a human half-life or safe interval.

Read the original source

How selective was LGD-3303 in the rat studies?

Muscle responses continued to rise while prostate and preputial-gland responses were smaller and tended to plateau. Prostate effects were reduced, not absent.

The 14-day castrated-rat experiments generally used five animals per group. Oral exposure prevented levator-ani loss and, at higher exposures, raised its weight above intact controls. At the muscle-normalizing exposure, prostate weight was around 20% of intact; at much higher exposure it could approach intact levels.

The muscle-versus-prostate pattern persisted with continuous infusion despite different peak concentrations. Prostate concentration exceeded muscle concentration in the tissue study, which used three rats per time point. This points toward differences in receptor response rather than less drug reaching the prostate.

The binding panel showed high AR affinity, with weaker but measurable activity at other receptors, including progesterone receptor. Relative selectivity does not establish organ safety.

Vajda et al. · rat PK/PD

Controlled preclinical pharmacology study

Vajda EG, López FJ, Rix P, Hill R, Chen Y, Lee KJ, O'Brien Z, Chang WY, Meglasson MD, Lee YH. Journal of Pharmacology and Experimental Therapeutics. 2009;328(2):663-670. DOI 10.1124/jpet.108.146811.

LGD-3303 prevented levator-ani loss and at higher exposures exceeded intact muscle weight. Prostate response was reduced but could approach intact weight at high exposure. Selectivity persisted across oral and infusion exposure despite higher prostate concentrations. Elevated LH declined at higher exposures. Day-14 rat Tmax was 0.7 to 2.8 hours and terminal half-life 4.3 to 8.7 hours; neither is human PK.

Participants / model: Castrated male Sprague-Dawley rats, generally five per group; tissue distribution three per time point
Treatment: Oral or continuously infused LGD-3303 across exposure groups
Follow-up: 14-day rat oral/infusion experiments
Study design: Controlled PK/PD animal study
Funding: Ligand Pharmaceuticals-associated study

The concentration-time and tissue data are rat pharmacokinetics, not a human half-life or safe interval.

Read the original source

Vajda et al. · osteopenic rats

Controlled preclinical combination study

Vajda EG, Hogue A, Griffiths KN, Chang WY, Burnett K, Chen Y, Marschke K, Mais DE, Pedram B, Shen Y, van Oeveren A, Zhi L, López FJ, Meglasson MD. Journal of Bone and Mineral Research. 2009;24(2):231-240. DOI 10.1359/jbmr.081007.

In ovariectomized rats, LGD-3303 increased gastrocnemius weight and selected DXA, cortical formation, geometry and ex-vivo strength measures. Cancellous bone-volume increases with LGD-3303 or alendronate alone were small and nonsignificant; combination results were endpoint-specific. Ovariectomized arms contained 11 rats each, with nine sham controls. All authors were Ligand employees.

Participants / model: Ovariectomized female rats and orchidectomized male rats
Treatment: LGD-3303, alendronate, combination, and controls
Follow-up: 12-week treatment after seven weeks of osteopenia development
Study design: Controlled preclinical combination study
Funding: Ligand Pharmaceuticals-associated study

The study measured bone surrogates in hormone-deficient rats. It collected no human fracture, mobility, or safety outcome, and combination arms also received alendronate.

Read the original source

What did the muscle and bone study measure?

Hormone-deficient rats gained muscle weight and improved several bone measures, including ex-vivo strength. Some cancellous-bone results were nonsignificant.

The longer osteopenic-rat experiment used 12 weeks of oral treatment, with 11 animals in each ovariectomized treatment group and nine sham controls. LGD-3303 increased gastrocnemius weight, reduced an inguinal fat pad and improved selected BMD, cortical-formation, geometry and mechanical-load measures.

LGD-3303 and alendronate alone produced small, nonsignificant cancellous bone-volume increases. Their combination improved some outcomes, without a uniform advantage across every endpoint. Fractures, mobility, pain and human body composition were not measured. Both Vajda papers came from Ligand employees.

Vajda et al. · osteopenic rats

Controlled preclinical combination study

Vajda EG, Hogue A, Griffiths KN, Chang WY, Burnett K, Chen Y, Marschke K, Mais DE, Pedram B, Shen Y, van Oeveren A, Zhi L, López FJ, Meglasson MD. Journal of Bone and Mineral Research. 2009;24(2):231-240. DOI 10.1359/jbmr.081007.

In ovariectomized rats, LGD-3303 increased gastrocnemius weight and selected DXA, cortical formation, geometry and ex-vivo strength measures. Cancellous bone-volume increases with LGD-3303 or alendronate alone were small and nonsignificant; combination results were endpoint-specific. Ovariectomized arms contained 11 rats each, with nine sham controls. All authors were Ligand employees.

Participants / model: Ovariectomized female rats and orchidectomized male rats
Treatment: LGD-3303, alendronate, combination, and controls
Follow-up: 12-week treatment after seven weeks of osteopenia development
Study design: Controlled preclinical combination study
Funding: Ligand Pharmaceuticals-associated study

The study measured bone surrogates in hormone-deficient rats. It collected no human fracture, mobility, or safety outcome, and combination arms also received alendronate.

Read the original source

Vajda et al. · rat PK/PD

Controlled preclinical pharmacology study

Vajda EG, López FJ, Rix P, Hill R, Chen Y, Lee KJ, O'Brien Z, Chang WY, Meglasson MD, Lee YH. Journal of Pharmacology and Experimental Therapeutics. 2009;328(2):663-670. DOI 10.1124/jpet.108.146811.

LGD-3303 prevented levator-ani loss and at higher exposures exceeded intact muscle weight. Prostate response was reduced but could approach intact weight at high exposure. Selectivity persisted across oral and infusion exposure despite higher prostate concentrations. Elevated LH declined at higher exposures. Day-14 rat Tmax was 0.7 to 2.8 hours and terminal half-life 4.3 to 8.7 hours; neither is human PK.

Participants / model: Castrated male Sprague-Dawley rats, generally five per group; tissue distribution three per time point
Treatment: Oral or continuously infused LGD-3303 across exposure groups
Follow-up: 14-day rat oral/infusion experiments
Study design: Controlled PK/PD animal study
Funding: Ligand Pharmaceuticals-associated study

The concentration-time and tissue data are rat pharmacokinetics, not a human half-life or safe interval.

Read the original source

Has LGD-3303 been tested in people?

The cited records include no human administration study. ClinicalTrials.gov lists no exact-name study. They provide no human half-life, oral bioavailability, useful exposure, strength, body composition, adverse-event rate, or interaction profile.

A 2023 horse metabolism study helps anti-doping laboratories identify urinary and plasma metabolites. It cannot be converted into human PK or efficacy.

ClinicalTrials.gov · no LGD-3303 study listed

Clinical trial registry

ClinicalTrials.gov records for LGD-3303 and its cited aliases.

ClinicalTrials.gov lists no study under LGD-3303 or its cited aliases. The cited literature also includes no human administration or pharmacokinetic paper.

Participants / model: ClinicalTrials.gov records
Treatment: LGD-3303

Read the original source

Nilsson Broberg et al. · horse metabolism

Animal anti-doping metabolism study

Nilsson Broberg M, Knych H, Bondesson U, Pettersson C, Tidstedt B, Stanley S, Thevis M, Hedeland M. Journal of Pharmaceutical and Biomedical Analysis. 2023;233:115468. DOI 10.1016/j.jpba.2023.115468.

One mare and one gelding received a single oral administration. Plasma and urine were collected through 96 hours; eight metabolites were tentatively identified, and one monohydroxylated metabolite persisted longest in the sampled matrices.

Participants / model: Two Thoroughbred horses: one mare and one gelding
Treatment: Single oral LGD-3303 administration
Follow-up: Blood and urine collection through 96 hours
Study design: In-vivo equine metabolism study

Equine detection data are not human PK, efficacy, or safety data.

Read the original source

Chinese and Russian records · no additional efficacy study

Literature and registry records

Chinese and Russian literature and registry records for LGD-3303.

The cited Chinese and Russian records include reviews, catalogs, anti-doping analyses, and copies of existing rat work, but no additional LGD-3303 clinical or animal efficacy study.

Participants / model: Chinese- and Russian-language records

Read the original source

What is known about human safety and interactions?

No human LGD-3303 study quantifies risk, contraindications, interactions, monitoring, or a safe exposure. Its androgen-receptor activity makes endocrine and reproductive effects plausible, while FDA's SARM communication identifies cardiovascular, hepatic, sexual, fertility, and testicular concerns for the class.

FDA · SARM class warning

FDA safety communication

U.S. Food and Drug Administration, updated December 2025.

FDA states that marketed SARM bodybuilding products are unapproved drugs and lists serious cardiovascular, hepatic, reproductive, sexual, and testicular class concerns.

Participants / model: Consumers of marketed SARM products
Treatment: SARM class
Study design: Agency class-risk communication
Funding: U.S. FDA

Class context is not LGD-3303-specific incidence.

Read the original source

ClinicalTrials.gov · no LGD-3303 study listed

Clinical trial registry

ClinicalTrials.gov records for LGD-3303 and its cited aliases.

ClinicalTrials.gov lists no study under LGD-3303 or its cited aliases. The cited literature also includes no human administration or pharmacokinetic paper.

Participants / model: ClinicalTrials.gov records
Treatment: LGD-3303

Read the original source

Is LGD-3303 approved or permitted in tested sport?

The cited regulatory and clinical records show no approved medicine or clinical development result. WADA's 2026 S1.2 section prohibits the SARM class at all times with an open-ended list of examples. The primary papers identify LGD-3303 as a SARM; the list does not name it individually.

WADA 2026 · SARM class applies

Official anti-doping standard

World Anti-Doping Agency. The 2026 Prohibited List, effective 1 January 2026.

Section S1.2 prohibits SARMs at all times using an including-but-not-limited-to list. LGD-3303 is not named individually.

Participants / model: Athletes subject to the World Anti-Doping Code
Follow-up: Calendar year 2026
Study design: Anti-doping prohibited list
Funding: World Anti-Doping Agency

Class placement follows the primary pharmacology and is not presented as an explicit name in the list.

Read the original source

Vajda et al. · rat PK/PD

Controlled preclinical pharmacology study

Vajda EG, López FJ, Rix P, Hill R, Chen Y, Lee KJ, O'Brien Z, Chang WY, Meglasson MD, Lee YH. Journal of Pharmacology and Experimental Therapeutics. 2009;328(2):663-670. DOI 10.1124/jpet.108.146811.

LGD-3303 prevented levator-ani loss and at higher exposures exceeded intact muscle weight. Prostate response was reduced but could approach intact weight at high exposure. Selectivity persisted across oral and infusion exposure despite higher prostate concentrations. Elevated LH declined at higher exposures. Day-14 rat Tmax was 0.7 to 2.8 hours and terminal half-life 4.3 to 8.7 hours; neither is human PK.

Participants / model: Castrated male Sprague-Dawley rats, generally five per group; tissue distribution three per time point
Treatment: Oral or continuously infused LGD-3303 across exposure groups
Follow-up: 14-day rat oral/infusion experiments
Study design: Controlled PK/PD animal study
Funding: Ligand Pharmaceuticals-associated study

The concentration-time and tissue data are rat pharmacokinetics, not a human half-life or safe interval.

Read the original source

ClinicalTrials.gov · no LGD-3303 study listed

Clinical trial registry

ClinicalTrials.gov records for LGD-3303 and its cited aliases.

ClinicalTrials.gov lists no study under LGD-3303 or its cited aliases. The cited literature also includes no human administration or pharmacokinetic paper.

Participants / model: ClinicalTrials.gov records
Treatment: LGD-3303

Read the original source

Did Chinese- or Russian-language sources add a local trial?

The cited Chinese and Russian records include no additional compound-specific clinical or animal efficacy study. They comprise reviews, chemical catalogs, anti-doping analyses, or copies and summaries of the original rat work.

Chinese and Russian records · no additional efficacy study

Literature and registry records

Chinese and Russian literature and registry records for LGD-3303.

The cited Chinese and Russian records include reviews, catalogs, anti-doping analyses, and copies of existing rat work, but no additional LGD-3303 clinical or animal efficacy study.

Participants / model: Chinese- and Russian-language records

Read the original source

Does it increase libido?

The rat results changed direction with prior sexual experience and depended on hormone priming. The cited records include no human libido study.

Experienced ovariectomized female rats spent more time near males, while naive rats showed reduced preference. Flutamide blocked the preference effect. Proceptivity and lordosis required selected estradiol/progesterone and exposure conditions; high-baseline responders were excluded from one experiment.

These were four small randomized experiments, generally five to ten animals per condition. The paper’s direct brain-distribution claims cite unpublished work. Published behavior alone cannot establish a human blood-brain exposure profile.

Kudwa et al. · hormone-dependent female-rat behavior

Controlled animal behavior study

Kudwa AE, López FJ, McGivern RF, Handa RJ. Endocrinology. 2010;151(6):2659-2668. DOI 10.1210/en.2009-1289.

Four experiments in ovariectomized female rats found experience- and estrogen-dependent effects. LGD-3303 increased male-directed preference in sexually experienced rats, reduced it in naive rats, and affected proceptive behavior or lordosis only in selected higher-exposure and estradiol-primed conditions; flutamide blocked the preference effect.

Participants / model: Ovariectomized female Sprague-Dawley rats in four experiments, generally five to ten per condition
Treatment: Oral LGD-3303, vehicle, hormonal priming, and antagonist conditions
Follow-up: One- and seven-day preference experiments and one- and nine-day sexual-behavior experiments
Study design: Randomized controlled animal behavior study

The study measured rat behavior and collected no human efficacy or psychiatric-safety outcome.

Read the original source

What do we know about suppression and half-life?

The rat study measured central androgen feedback and rat PK. It did not measure testosterone shutdown, sperm production or recovery in intact men.

Higher exposures lowered the elevated LH of castrated rats toward intact levels. That shows feedback, but a castrated animal cannot show suppression of its missing testes or a human recovery curve.

Day-14 oral rat groups had reported terminal half-lives of 4.3 to 8.7 hours and Tmax values of 0.7 to 2.8 hours. These are rat values. The two-horse metabolism study likewise measured detection, without establishing a human interval or duration of action.

Vajda et al. · rat PK/PD

Controlled preclinical pharmacology study

Vajda EG, López FJ, Rix P, Hill R, Chen Y, Lee KJ, O'Brien Z, Chang WY, Meglasson MD, Lee YH. Journal of Pharmacology and Experimental Therapeutics. 2009;328(2):663-670. DOI 10.1124/jpet.108.146811.

LGD-3303 prevented levator-ani loss and at higher exposures exceeded intact muscle weight. Prostate response was reduced but could approach intact weight at high exposure. Selectivity persisted across oral and infusion exposure despite higher prostate concentrations. Elevated LH declined at higher exposures. Day-14 rat Tmax was 0.7 to 2.8 hours and terminal half-life 4.3 to 8.7 hours; neither is human PK.

Participants / model: Castrated male Sprague-Dawley rats, generally five per group; tissue distribution three per time point
Treatment: Oral or continuously infused LGD-3303 across exposure groups
Follow-up: 14-day rat oral/infusion experiments
Study design: Controlled PK/PD animal study
Funding: Ligand Pharmaceuticals-associated study

The concentration-time and tissue data are rat pharmacokinetics, not a human half-life or safe interval.

Read the original source

Nilsson Broberg et al. · horse metabolism

Animal anti-doping metabolism study

Nilsson Broberg M, Knych H, Bondesson U, Pettersson C, Tidstedt B, Stanley S, Thevis M, Hedeland M. Journal of Pharmaceutical and Biomedical Analysis. 2023;233:115468. DOI 10.1016/j.jpba.2023.115468.

One mare and one gelding received a single oral administration. Plasma and urine were collected through 96 hours; eight metabolites were tentatively identified, and one monohydroxylated metabolite persisted longest in the sampled matrices.

Participants / model: Two Thoroughbred horses: one mare and one gelding
Treatment: Single oral LGD-3303 administration
Follow-up: Blood and urine collection through 96 hours
Study design: In-vivo equine metabolism study

Equine detection data are not human PK, efficacy, or safety data.

Read the original source

Studies and sources

PubChem · LGD-3303 identity

Official chemical identity record

National Center for Biotechnology Information. PubChem CID 25195253.

The record identifies LGD-3303 with formula C16H14ClF3N2O, molecular weight 342.74 g/mol, CAS 917891-35-1, and UNII 7N4E1X2RJM.

Study design: Chemical database record

Identity is not approval or retail-product authentication.

Read the original source

Vajda et al. · rat PK/PD

Controlled preclinical pharmacology study

Vajda EG, López FJ, Rix P, Hill R, Chen Y, Lee KJ, O'Brien Z, Chang WY, Meglasson MD, Lee YH. Journal of Pharmacology and Experimental Therapeutics. 2009;328(2):663-670. DOI 10.1124/jpet.108.146811.

LGD-3303 prevented levator-ani loss and at higher exposures exceeded intact muscle weight. Prostate response was reduced but could approach intact weight at high exposure. Selectivity persisted across oral and infusion exposure despite higher prostate concentrations. Elevated LH declined at higher exposures. Day-14 rat Tmax was 0.7 to 2.8 hours and terminal half-life 4.3 to 8.7 hours; neither is human PK.

Participants / model: Castrated male Sprague-Dawley rats, generally five per group; tissue distribution three per time point
Treatment: Oral or continuously infused LGD-3303 across exposure groups
Follow-up: 14-day rat oral/infusion experiments
Study design: Controlled PK/PD animal study
Funding: Ligand Pharmaceuticals-associated study

The concentration-time and tissue data are rat pharmacokinetics, not a human half-life or safe interval.

Read the original source

Vajda et al. · osteopenic rats

Controlled preclinical combination study

Vajda EG, Hogue A, Griffiths KN, Chang WY, Burnett K, Chen Y, Marschke K, Mais DE, Pedram B, Shen Y, van Oeveren A, Zhi L, López FJ, Meglasson MD. Journal of Bone and Mineral Research. 2009;24(2):231-240. DOI 10.1359/jbmr.081007.

In ovariectomized rats, LGD-3303 increased gastrocnemius weight and selected DXA, cortical formation, geometry and ex-vivo strength measures. Cancellous bone-volume increases with LGD-3303 or alendronate alone were small and nonsignificant; combination results were endpoint-specific. Ovariectomized arms contained 11 rats each, with nine sham controls. All authors were Ligand employees.

Participants / model: Ovariectomized female rats and orchidectomized male rats
Treatment: LGD-3303, alendronate, combination, and controls
Follow-up: 12-week treatment after seven weeks of osteopenia development
Study design: Controlled preclinical combination study
Funding: Ligand Pharmaceuticals-associated study

The study measured bone surrogates in hormone-deficient rats. It collected no human fracture, mobility, or safety outcome, and combination arms also received alendronate.

Read the original source

Kudwa et al. · hormone-dependent female-rat behavior

Controlled animal behavior study

Kudwa AE, López FJ, McGivern RF, Handa RJ. Endocrinology. 2010;151(6):2659-2668. DOI 10.1210/en.2009-1289.

Four experiments in ovariectomized female rats found experience- and estrogen-dependent effects. LGD-3303 increased male-directed preference in sexually experienced rats, reduced it in naive rats, and affected proceptive behavior or lordosis only in selected higher-exposure and estradiol-primed conditions; flutamide blocked the preference effect.

Participants / model: Ovariectomized female Sprague-Dawley rats in four experiments, generally five to ten per condition
Treatment: Oral LGD-3303, vehicle, hormonal priming, and antagonist conditions
Follow-up: One- and seven-day preference experiments and one- and nine-day sexual-behavior experiments
Study design: Randomized controlled animal behavior study

The study measured rat behavior and collected no human efficacy or psychiatric-safety outcome.

Read the original source

Nilsson Broberg et al. · horse metabolism

Animal anti-doping metabolism study

Nilsson Broberg M, Knych H, Bondesson U, Pettersson C, Tidstedt B, Stanley S, Thevis M, Hedeland M. Journal of Pharmaceutical and Biomedical Analysis. 2023;233:115468. DOI 10.1016/j.jpba.2023.115468.

One mare and one gelding received a single oral administration. Plasma and urine were collected through 96 hours; eight metabolites were tentatively identified, and one monohydroxylated metabolite persisted longest in the sampled matrices.

Participants / model: Two Thoroughbred horses: one mare and one gelding
Treatment: Single oral LGD-3303 administration
Follow-up: Blood and urine collection through 96 hours
Study design: In-vivo equine metabolism study

Equine detection data are not human PK, efficacy, or safety data.

Read the original source

ClinicalTrials.gov · no LGD-3303 study listed

Clinical trial registry

ClinicalTrials.gov records for LGD-3303 and its cited aliases.

ClinicalTrials.gov lists no study under LGD-3303 or its cited aliases. The cited literature also includes no human administration or pharmacokinetic paper.

Participants / model: ClinicalTrials.gov records
Treatment: LGD-3303

Read the original source

FDA · SARM class warning

FDA safety communication

U.S. Food and Drug Administration, updated December 2025.

FDA states that marketed SARM bodybuilding products are unapproved drugs and lists serious cardiovascular, hepatic, reproductive, sexual, and testicular class concerns.

Participants / model: Consumers of marketed SARM products
Treatment: SARM class
Study design: Agency class-risk communication
Funding: U.S. FDA

Class context is not LGD-3303-specific incidence.

Read the original source

WADA 2026 · SARM class applies

Official anti-doping standard

World Anti-Doping Agency. The 2026 Prohibited List, effective 1 January 2026.

Section S1.2 prohibits SARMs at all times using an including-but-not-limited-to list. LGD-3303 is not named individually.

Participants / model: Athletes subject to the World Anti-Doping Code
Follow-up: Calendar year 2026
Study design: Anti-doping prohibited list
Funding: World Anti-Doping Agency

Class placement follows the primary pharmacology and is not presented as an explicit name in the list.

Read the original source

Chinese and Russian records · no additional efficacy study

Literature and registry records

Chinese and Russian literature and registry records for LGD-3303.

The cited Chinese and Russian records include reviews, catalogs, anti-doping analyses, and copies of existing rat work, but no additional LGD-3303 clinical or animal efficacy study.

Participants / model: Chinese- and Russian-language records

Read the original source

Why is LGD-3303 in D tier?

D: convincing activity in the tested rat models, with no human benefit or pharmacokinetic study in the cited evidence. Muscle weight, bone mechanics and hormone-dependent rat behavior do not establish performance, libido or safety in people.