LG121071

Overview

LG121071 (also written LG-121071 or LGD-121071; full chemical name 4-ethyl-1,2,3,4-tetrahydro-6-(trifluoromethyl)-8-pyridono[5,6-g]-quinoline) is an early nonsteroidal selective androgen receptor modulator (SARM) developed by Ligand Pharmaceuticals and first described in 1999 (Hamann et al., Journal of Medicinal Chemistry, PMID 9925725). It is built on a tricyclic tetrahydroquinolinone (trifluoromethyl-quinolinone) scaffold — a true nonsteroidal SARM. It is NOT a peptide (it is not an amino-acid chain) and NOT a steroid (its scaffold is nonsteroidal).

LG121071 is historically important: it is among the first orally active nonsteroidal androgens ever described, and it is a chemical and conceptual predecessor to Ligand's later "LGD" series, which includes ligandrol (LGD-4033). It is reported as a high-affinity full agonist of the androgen receptor (Ki ~17 nM) with potency described as comparable to dihydrotestosterone (DHT). It appears on this peptide reference because it is discussed alongside peptides and later SARMs in the fitness and "research chemical" community — not because it is one.

Chemistry and structure

LG121071 is a nonsteroidal tricyclic small molecule — an amino-acid chain it is not.

Mechanism of action

• Androgen receptor (AR) full agonism — high affinity. LG121071 is reported as a full agonist of the androgen receptor with high binding affinity (Ki ~17 nM), with binding/activation potency described as equivalent to dihydrotestosterone (DHT). Sources: Hamann et al., J Med Chem 1999 (PMID 9925725) and secondary summaries. [In vitro]
• Nonsteroidal — not aromatized and not 5alpha-reduced. As a tricyclic tetrahydroquinolinone (not a steroid), LG121071 cannot be aromatized to estrogens or 5alpha-reduced. This is the mechanistic rationale offered for a tissue-selective (full anabolic / reduced androgenic) profile; the tissue-selectivity claim derives from the SARM design concept, not from human data. [Hypothesis]
• Tissue-selective androgenic/anabolic profile (class concept). The SARM-class concept — full anabolic activity in muscle with reduced androgenic activity in prostate and seminal vesicles — was historically tested in castrated-rat levator-ani vs prostate/seminal-vesicle assays. Specific quantitative in-vivo tissue-selectivity ratios for LG121071 were not located in an open source and should be treated as not established for this compound. [Animal]

Research and evidence

LG121071 has only preclinical data (in vitro + rodent) and analytical (doping-control) work. There are no human trials of any phase, and no regulatory approval.

Human evidence in context. There is none. Every claim about LG121071 rests on in-vitro binding data, rodent work, and analytical chemistry. There are no human efficacy data for muscle, performance, or body composition, and no human safety or pharmacokinetic data — its half-life is not established. The 2015 metabolism work was performed not because anyone used it clinically, but so that anti-doping laboratories could detect its misuse.

Status and regulation

• Regulatory approval: None. LG121071 is not approved by the FDA, the EMA, or any other regulator for any indication. It is a preclinical research compound — no human clinical trials have been identified — and exists otherwise only as an analytical reference material.
• Anti-doping: Prohibited by the World Anti-Doping Agency (WADA) at all times (in- and out-of-competition), under S1.2 (Other Anabolic Agents — SARMs). A validated urine detection method exists (Knoop et al. 2015, PMID 25906032). The precise sub-code should be confirmed against the current-year WADA Prohibited List, which is revised annually. WADA is a sport-eligibility axis and is separate from any question of legality.
• Market reality: Outside preclinical research it is sold only as an unregulated "research chemical" of unknown identity, purity, and potency.

Safety

Documented and expected safety signals (tagged by evidence type):

• No human safety data [Human — none exist]. The compound never entered human trials; there are no clinical safety, dosing, or pharmacokinetic data for LG121071.
• SARM-class hepatotoxicity / drug-induced liver injury (DILI) [Human — class-level]. The FDA has warned that SARM-containing body-building products are linked to serious liver injury, including cases of acute liver failure. This is a class-level warning; it has not been studied specifically for LG121071. Sources: FDA SARM safety communications; NIH LiverTox.
• Testosterone / HPTA suppression [Hypothesis for LG121071]. Androgen-receptor agonists as a class suppress endogenous testosterone and gonadotropins. This is expected on mechanistic grounds but has not been directly measured for LG121071. No dosing, "cycle," or post-cycle guidance is given here.

Legal status

How it compares

LG121071 is often grouped with other SARMs and with non-SARM "research chemicals." The honest framing:

• Ligandrol (LGD-4033) — a later Ligand ("LGD") SARM and the best-known chemical descendant of the lineage LG121071 helped begin. LGD-4033 reached human trials; LG121071 never did.
• Ostarine, testolone (RAD-140), andarine, S-23 — other nonsteroidal SARMs that share LG121071's mechanism (AR agonism), expected testosterone-suppression risk, WADA S1.2 status, and lack of approval. LG121071 stands out as one of the earliest of the class and as purely preclinical — it has no human data at all.
• Cardarine (GW-501516) and stenabolic (SR9009) — frequently sold alongside SARMs but are NOT SARMs; cardarine is a PPARdelta agonist and stenabolic is a Rev-ErbA agonist, with different mechanisms and their own risks.
• MK-677 (ibutamoren) — frequently grouped with SARMs but is a growth-hormone secretagogue / ghrelin agonist, not a SARM.

The decisive point: LG121071 is historically important but purely preclinical — not approved for anything, with no human safety or efficacy data whatsoever. See the Muscle, growth & hormones overview.

Common misconceptions

• "LG121071 is a peptide." No. It is a nonsteroidal tricyclic small molecule (C15H15F3N2O, ~296.29 g/mol). It is covered here only because it is discussed and stacked with peptides and later SARMs.
• "Its DHT-comparable potency means the muscle benefits are proven." No. The "comparable to DHT" description is a receptor-binding / in-vitro potency statement, not human efficacy. LG121071 has no human trials and no proven physique or performance benefit.
• "It's a milder, safer, legal alternative to steroids." No. It is not approved, is expected to suppress natural testosterone, has no human safety data, and belongs to a class the FDA links to serious liver injury. "SARM" does not mean "safe."
• "Buying it as a 'research chemical' means it's clean and correctly dosed." No. Independent testing (JAMA 2017) found most products sold as SARMs were mislabeled, contained a different drug, or contained nothing.

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This entry is educational and summarizes published research and public regulatory information as of the "updated" date above. It is not medical advice, not legal advice, a recommendation, or a guide to obtaining or using any substance.