LGD-2941

Overview

LGD-2941 is a nonsteroidal selective androgen receptor modulator (SARM) of the quinolinone (6-anilino-quinolinone) chemotype. It is not a peptide and it is not an approved medicine — it is a discontinued investigational drug that today is encountered only as a research reagent sold by unregulated vendors.

Its development history is short. LGD-2941 was originated by Ligand Pharmaceuticals and taken into Phase 1 under a collaboration with TAP Pharmaceutical Products. Phase 1 development commenced in April 2005 (per Ligand's SEC 10-K), and single-dose pharmacokinetic and adverse-event data in healthy volunteers were presented at ENDO 2008 [Human — Phase 1]. Development was subsequently discontinued — the SARM agreement was assigned to Abbott in 2008 following the Takeda/Abbott separation of TAP — and Ligand later pivoted its SARM program to LGD-4033 (ligandrol).

Preclinically, LGD-2941 was reported to be orally active, with anabolic activity in muscle and improved bone strength while showing a reduced effect on the prostate in rodent models [Animal]. Those are animal findings and do not establish human efficacy or safety. Human data are limited to a discontinued Phase 1 program and never advanced toward approval.

Chemistry and structure

LGD-2941 is a small synthetic molecule, not a peptide. Its structure is built on a quinolinone scaffold (a 6-anilino-quinolinone), unrelated to the steroidal androgen skeleton.

Mechanism of action

• Androgen receptor modulation [In vitro] / [Animal] — LGD-2941 binds and selectively modulates the androgen receptor (AR). As with other nonsteroidal SARMs, its tissue selectivity is attributed not to a variant receptor but to tissue-specific differences in AR coregulator (cofactor) recruitment, producing preferential agonism in muscle and bone.

• Anabolic muscle/bone selectivity with reduced prostate effect [Animal] — In preclinical rodent models, LGD-2941 showed anabolic activity in muscle with a reduced effect on the prostate in a rat model of hypogonadism, and improved bone strength in a rat model of post-menopausal osteoporosis. These are animal findings; human tissue-selective anabolic efficacy is not established.

• Oral bioavailability [Animal] / [Human — Phase 1, values not located] — Reported to be orally active, with improved oral bioavailability relative to earlier compounds in the Ligand SARM series. Quantitative human PK parameters (half-life, Cmax, Tmax, bioavailability %) were not located in accessible sources.

Research and evidence

LGD-2941's evidence base is thin and largely closed out:

• Chemistry/identity [In vitro] — Established: nonsteroidal quinolinone SARM, C17H16F6N2O2, MW 394.31, CAS 847235-85-2, PubChem CID 16750192.
• Development milestones [Human] — Verified via Ligand's SEC 10-K filings: Ligand-originated; Phase 1 with TAP; Phase 1 commenced April 2005; SARM agreement assigned to Abbott in 2008; program later pivoted to LGD-4033.
• Phase 1 human data [Human] — Single-dose PK and adverse-event data in healthy volunteers presented at ENDO 2008; development subsequently discontinued. (The primary ENDO 2008 abstract was not directly retrieved; the Phase 1 milestone, the ENDO 2008 presentation, and the discontinuation are corroborated by a secondary drug-pipeline database (AdisInsight) and by Ligand's SEC filings.)
• Preclinical efficacy [Animal] — Anabolic activity in muscle and improved bone strength with a reduced prostate effect in rodent models.
• Clinical trials [Human] — No registered clinical trial for LGD-2941 was found on ClinicalTrials.gov (0 records).

Quantitative preclinical potency/selectivity (EC50, anabolic:androgenic ratio) and human PK values were not located in accessible sources.

Status and regulation

• Highest phase reached: Phase 1, then discontinued.
• Approval status: Never approved for any indication by any regulator.
• Present status: Encountered only as a research reagent; not a marketed drug or a legal dietary supplement ingredient.

Safety

LGD-2941 has no compound-specific human safety database beyond a discontinued Phase 1 program. The signals below are therefore mostly class-based and must be read as such.

• SARM-class hepatotoxicity / drug-induced liver injury (DILI) [Human — class] / [Hypothesis — compound] — The SARM class is associated with clinically apparent cholestatic liver injury resembling anabolic-steroid jaundice, typically after 2-3 months of use, with canalicular ("bland") cholestasis on biopsy. The FDA has warned that SARMs can cause serious liver injury, including acute liver failure. No LGD-2941-specific hepatotoxicity data exist.

• Testosterone / HPTA suppression [Human — class] / [Hypothesis — compound] — As androgen-receptor agonists, SARMs as a class can suppress the hypothalamic-pituitary-testicular axis and endogenous testosterone production. LGD-2941-specific human endocrine data are not established.

• No compound-specific long-term human safety data [Human — none beyond Phase 1] — Human exposure is limited to a discontinued Phase 1 program. Preclinical selectivity does not guarantee a favorable human safety profile.

Contamination and mislabeling reality. Products sold online as "SARMs" are frequently not what the label says. Van Wagoner et al. (JAMA 2017;318(20):2004-2010; PMID 29183075) chemically analyzed 44 internet "SARM" products and found that only 52% contained any labeled SARM (and often not in the stated amount), 39% contained a different unapproved drug (e.g., ibutamoren/MK-677, GW501516, SR9009), and 9% contained no active compound at all [Human — market analysis]. A product label is therefore not a reliable statement of contents.

Legal status

The legal status of LGD-2941 has not been assessed here and varies by country. In general, SARMs are not approved medicines and are not lawful dietary-supplement ingredients in major markets; some jurisdictions further restrict their sale or possession. This is separate from anti-doping status.

Anti-doping (separate question): LGD-2941, as a SARM, is prohibited at all times (in- and out-of-competition) under the WADA Prohibited List, category S1.2 (Other Anabolic Agents) [Regulatory].

How it compares

LGD-2941 is best understood next to the compound that replaced it in its own developer's pipeline: ligandrol (LGD-4033), the SARM Ligand advanced after discontinuing LGD-2941. It also sits in the same nonsteroidal-SARM family as testolone (RAD-140) and ostarine (MK-2866) — but unlike those, LGD-2941 never accumulated a meaningful human literature and was dropped at Phase 1.

Common misconceptions

• "It's a peptide." No. LGD-2941 is a small-molecule nonsteroidal SARM (quinolinone chemotype), not a peptide.
• "It's an approved or clinically validated drug." No. It never gained approval and was discontinued at Phase 1. Human efficacy and safety were never established.
• "Preclinical selectivity means it's safe in humans." The reduced-prostate-effect data are from rodents. Animal selectivity does not translate into a demonstrated human safety margin.
• "It's a safer or legal alternative to steroids." It is neither. It is a discontinued research chemical with class-level liver and hormonal risks, and it is banned in sport.
• "The label tells me what I'm buying." For online "SARM" products, frequently not — JAMA 2017 found most were mislabeled or adulterated.