LGD-3303 Overview
LGD-3303 is a nonsteroidal, orally bioavailable selective androgen receptor modulator (SARM) originally developed by Ligand Pharmaceuticals. It is characterized in the primary literature as a high-affinity androgen receptor ligand with reported binding K_i of approximately 0.9 nM. LGD-3303 is widely referenced in androgen receptor pharmacology research, SARM structure-activity studies, and analytical reference-standard work, including LC-MS/MS panels for SARM detection in anti-doping analytical literature.
LGD-3303 is not approved for human or veterinary use and is supplied strictly for laboratory and analytical research purposes.
Mechanism of Action
LGD-3303 binds the androgen receptor ligand-binding domain with high affinity and acts as a tissue-differential AR ligand. Published in vitro and preclinical characterizations report functional selectivity, with differential transcriptional output across androgen-responsive cell types — full agonist transcriptional activity in cell models representative of muscle and bone tissue, and reduced (partial agonist) activity in prostate-derived reporter models.
Reported characterizations include:
- AR binding K_i ≈ 0.9 nM
- Oral bioavailability in published rodent pharmacokinetic studies
- Distinct AR ligand-binding domain conformational pattern reported relative to testosterone and steroidal androgens
- Non-aromatizable structural class
Chemical Structure & Identification
- Chemical Name: 9-Chloro-2-ethyl-1-methyl-3-(2,2,2-trifluoroethyl)-3H,6H,7H-pyrrolo[3,2-f]quinolin-7-one
- Synonyms: LGD3303; LGD 3303
- CAS Number: 917891-35-1
- Molecular Formula: C₁₆H₁₄ClF₃N₂O
- Molecular Weight: 342.74 g/mol
- PubChem CID: 25195253
- UNII: 7N4E1X2RJM
- ChemSpider: 35143239
Structural Description: LGD-3303 is built on a tricyclic pyrrolo[3,2-f]quinolin-7-one fused ring system, with a 9-chloro substituent, 2-ethyl and 1-methyl groups on the pyrrole ring, and an N-(2,2,2-trifluoroethyl) substituent. The chlorine atom and the trifluoroethyl group contribute electron-withdrawing character that influences receptor binding affinity and metabolic stability. The compound is structurally related to other Ligand Pharmaceuticals SARMs, including LGD-4033, and is frequently compared with them in published structure-activity studies. Structural identification and molecular data are referenced against PubChem.
Physical and Chemical Properties
- Appearance: Pale yellow to greenish-yellow solid
- Solubility: Soluble in DMSO; poorly soluble in water
- Stability: Stable under dry, cool, light-protected storage conditions
- Recommended storage: -20 °C for long-term stability
Research Focus Areas
LGD-3303 is commonly referenced in laboratory research involving:
- Androgen receptor binding and competition assays
- SARM structure-activity relationship (SAR) analysis
- Nuclear receptor selectivity profiling
- AR ligand-binding domain conformation and coregulator recruitment studies
- Analytical and reference-standard work, including LC-MS/MS method development referenced in anti-doping analytical literature
- Comparative SARM evaluation alongside other Ligand Pharmaceuticals compounds (LGD-4033, LGD-2226) and the broader nonsteroidal AR ligand class
Research Background & Regulatory Context
LGD-3303 is included on the World Anti-Doping Agency (WADA) Prohibited List under the anabolic agents category and has been documented in the analytical chemistry literature as a designer-drug analyte requiring inclusion in SARM screening panels. This regulatory and analytical record is part of the published scientific literature on the compound and reinforces that LGD-3303 is supplied strictly as a research reagent.
Research Use Disclaimer
LGD-3303 is intended strictly for laboratory research use only (RUO). Not for human consumption, clinical use, veterinary use, therapeutic application, or diagnostic purposes. All handling and use must comply with applicable federal, state, and local laws and institutional laboratory safety standards.
Summary
LGD-3303 is a structurally defined nonsteroidal selective androgen receptor modulator with extensive primary-literature support as a reference ligand in androgen receptor pharmacology, SARM SAR research, and anti-doping analytical method development. Its tricyclic pyrroloquinolinone scaffold and well-characterized binding profile make it a useful reference compound in controlled laboratory studies of androgen receptor signaling.
| CAS Number | 917891-35-1 |
| Other Names | LGD3303, LGD 3303, 1196133-39-7, 7N4E1X2RJM, UNII-7N4E1X2RJM, SCHEMBL4130914, CHEMBL5170697, DTXSID601028425, BCP20806, EX-A1672, AKOS037515574, DB13937, HY-103576, CS-0028120 |
| IUPAC Name | 9-chloro-2-ethyl-1-methyl-3-(2,2,2-trifluoroethyl)-6H-pyrrolo[3,2-f]quinolin-7-one |
| Molecular Formula | C₁₆H₁₄ClF₃N₂O |
| Molecular Weight | 342.74 |
| Dry-Fill Capsule Concentration | 10 |
| Liquid Concentration And Solution | 20mg/ml, PEG400 |
