LGD-3303

Overview

LGD-3303 is a non-peptide small molecule belonging to the pyrrolo[3,2-f]quinolinone class of selective androgen receptor modulators (SARMs). It has never been approved by the FDA or any regulatory agency for human use, and no human clinical trials have been conducted or registered. LGD-3303 is prohibited under WADA's S1.2 category (Other Anabolic Agents), which covers all SARMs as a class. All available data are preclinical, derived from in vitro AR binding assays and in vivo studies in castrated rats and horses.

Mechanism of Action

LGD-3303 is a nonsteroidal androgen receptor (AR) agonist. In castrated rat studies (Vajda et al. 2009, PMID 19017848), it bound and activated the AR to drive potent anabolic activity in levator ani muscle while acting only as a partial agonist in androgenic tissues (preputial gland, ventral prostate), never stimulating ventral prostate above intact-animal levels despite rising plasma concentrations. Tissue-selective activity persisted regardless of oral versus continuous-infusion dosing and despite higher local drug concentrations in prostate than in muscle, indicating the selectivity arises from altered molecular interaction at the AR itself rather than from differences in pharmacokinetic exposure or tissue distribution.

Research Summary

No human data exist for LGD-3303. No completed or registered clinical trials were found on ClinicalTrials.gov, and no PubMed record of a Phase 1 or later human trial exists. In castrated Sprague-Dawley rats, LGD-3303 showed potent anabolic (levator ani muscle) agonist activity but only partial agonist activity on androgenic tissues (ventral prostate, preputial gland); tissue selectivity was maintained across both oral dosing and continuous infusion despite very different plasma exposure-time profiles (Vajda et al. 2009, PMID 19017848). In horses dosed orally at 0.05 mg/kg, eight metabolites (including hydroxylated and carboxylated forms with glucuronic acid conjugates) were tentatively identified in plasma and urine for doping-control purposes, with a monohydroxylated metabolite identified as the most sensitive analytical marker (Nilsson Broberg, Knych, Bondesson et al. 2023, PMID 37224728).

Vendors selling LGD-3303

Scored vendors carrying LGD-3303, ranked by trust grade. Grades are computed from indexed Certificates of Analysis. Full $/mg pricing is on the comparison page.

Reported Side Effects

• No human safety or adverse-event data exist
• Not FDA-approved for any indication
• Prohibited under WADA S1.2 (SARMs as a class)
• Gray-market material carries unknown purity/identity risk
• No published human or additional animal toxicology data

Compare LGD-3303 with Others

Research References

• 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. 2009. PMID 19017848.
• Equine in vivo metabolite profiling of the selective androgen receptor modulator LGD-3303 for doping control. 2023. PMID 37224728.
• PubChem Compound Summary for CID 25195253, LGD-3303.

Frequently asked questions

Has LGD-3303 been independently lab-tested?

Disclosed Labs has collected 2 Certificates of Analysis (COA) for LGD-3303 from 2 independent testing labs. 1 vendor has submitted material for testing. Products average 99.0% tested purity across the corpus. Full testing data is available at https://www.disclosedlabs.com/peptides/lgd-3303/testing.

Where can researchers source LGD-3303?

1 vendor with Disclosed Labs trust grades currently list LGD-3303, including Kimera Chems. Compare live prices and lab-verified COAs at https://www.disclosedlabs.com/prices/lgd-3303.

How does LGD-3303 work?

LGD-3303 is a nonsteroidal androgen receptor (AR) agonist. In castrated rat studies (Vajda et al. 2009, PMID 19017848), it bound and activated the AR to drive potent anabolic activity in levator ani muscle while acting only as a partial agonist in androgenic tissues (preputial gland, ventral prostate), never stimulating ventral prostate above intact-animal levels despite rising plasma concentrations. Tissue-selective activity persisted regardless of oral versus continuous-infusion dosing and despite higher local drug concentrations in prostate than in muscle, indicating the selectivity arises from altered molecular interaction at the AR itself rather than from differences in pharmacokinetic exposure or tissue distribution.

What does the research say about LGD-3303?

No human data exist for LGD-3303. No completed or registered clinical trials were found on ClinicalTrials.gov, and no PubMed record of a Phase 1 or later human trial exists. In castrated Sprague-Dawley rats, LGD-3303 showed potent anabolic (levator ani muscle) agonist activity but only partial agonist activity on androgenic tissues (ventral prostate, preputial gland); tissue selectivity was maintained across both oral dosing and continuous infusion despite very different plasma exposure-time profiles (Vajda et al. 2009, PMID 19017848). In horses dosed orally at 0.05 mg/kg, eight metabolites (including hydroxylated and carboxylated forms with glucuronic acid conjugates) were tentatively identified in plasma and urine for doping-control purposes, with a monohydroxylated metabolite identified as the most sensitive analytical marker (Nilsson Broberg, Knych, Bondesson et al. 2023, PMID 37224728).