LGD-4033 / Ligandrol

LGD-4033 has a more substantial clinical development history than any other SARM — and understanding what that clinical history actually covers is the most important framing for anyone considering community use.

Ligand Pharmaceuticals developed LGD-4033 as part of a broader SARM research program in the mid-2000s, targeting muscle wasting, cachexia, hypogonadism, and osteoporosis. The compound was licensed to Viking Therapeutics, which renamed it VK5211 and advanced it into Phase 2 clinical development for hip fracture recovery. The Basaria et al. 2013 Phase 1 trial in healthy men is the foundational human safety and pharmacology study — the study that the community cites when arguing LGD-4033 is 'the most studied SARM' and has 'proven safety in clinical trials.' The Phase 1 was conducted at doses of 0.1, 0.3, and 1 mg/day for 21 days. The highest dose studied was 1 mg. The community protocol is typically 5-20 mg/day for 42-56 days. The dose gap between the evidence base and the community practice is as wide as 5-fold to 200-fold. The duration gap is 2-3 fold. This is not a minor extrapolation — it is applying safety data from one pharmacological regime to a substantially different pharmacological regime.

THE CENTRAL TENSION

LGD-4033 holds a paradoxical position in the SARM evidence landscape: it has the most clinical trial data of any SARM, but that data was generated at doses that are a fraction of what the community uses. The Phase 1 trial at 0.1-1 mg/day with no significant liver enzyme changes is genuinely reassuring for that dose range. It is not reassuring for the 5-20 mg/day doses that community users employ. The Phase 2 hip fracture trial (VK5211) at efficacy doses in elderly patients showed no drug-related serious adverse events — but elderly hip fracture patients and young men seeking body composition enhancement represent different populations with different baseline risks. The community's appeal to LGD-4033's 'clinical data' as a safety endorsement conflates evidence from one dose range with use at a categorically different dose range. Understanding this distinction is the most important critical thinking exercise for anyone considering LGD-4033.

LGD-4033 has been detected in competitive athletes across multiple sports. The most prominent case: Canelo Álvarez, WBC light heavyweight champion, tested positive for LGD-4033 in two samples in February 2018 before his scheduled rematch with Gennady Golovkin. Álvarez and his team attributed the positive test to contaminated beef from Mexico, where clenbuterol contamination in cattle is a documented public health issue (a related doping controversy). VADA and WBC ultimately accepted the contaminated meat explanation; the WBC sanctioned a 6-month suspension that Álvarez agreed to serve via a fight postponement; the positive was not treated as a voluntary doping violation. The contaminated supplement/food defense has been used in multiple SARM doping cases — and while legitimate contamination does occur (both food and supplement contamination with trace SARMs has been documented), the defense is also used strategically in cases involving deliberate doping. Multiple Australian NRL (rugby league) players and junior players tested positive for LGD-4033 in 2018-2019 in a broader SARM contamination/doping scandal. Detection methodology for LGD-4033: WADA-accredited laboratories use LC-MS/MS to detect LGD-4033 and its metabolites; detection window estimated at 1-3 weeks for parent compound, potentially longer for metabolites depending on dose and individual metabolism.

LGD-4033 is a nonsteroidal, orally active, selective AR agonist. It binds the androgen receptor with high affinity and selectivity, acting as a full agonist in muscle and bone and a partial agonist or antagonist in the prostate. The tissue selectivity mechanism is the same as described for RAD-140 and Ostarine — differential AR coregulator expression in different tissues produces different receptor response profiles with the same ligand. LGD-4033 is generally characterized as producing stronger AR activation in muscle than Ostarine but comparable to or slightly below RAD-140. The clinical pharmacology demonstrated in the Phase 1 trial: at 1 mg/day for 21 days, +1.21 kg lean mass with no fat change — a notable effect for such a low dose over only 3 weeks. This lean mass response rate at 1 mg exceeds most injectable testosterone protocols in per-mg efficiency, suggesting a highly potent AR activation profile. The dose-response relationship at community doses (5-20 mg) is not characterized in controlled clinical trials — the community lean mass effects at these doses are extrapolated from the Phase 1 response, with the assumption that higher doses produce proportionally greater anabolic response. Whether this linear extrapolation holds, and what the dose-response for adverse effects looks like in this range, is not established.

LGD-4033 produces dose-dependent HPTA suppression — this is established in Phase 1 clinical data. At community doses (5-20 mg/day), clinicians treating SARM users consistently report testosterone values in the low-normal to hypogonadal range during cycles. The degree of suppression is typically characterized as greater than Ostarine but somewhat less than RAD-140 at equivalent community doses — but all three produce clinically significant suppression requiring PCT. The SHBG decline documented in Phase 1 is pharmacologically meaningful: reduced SHBG increases free testosterone fraction relative to total testosterone, partially buffering the suppression of total testosterone. This means total testosterone measurements underestimate functional androgen status during LGD-4033 use to some degree — but at community doses, total testosterone still falls substantially.

Feature

LGD-4033

RAD-140

Ostarine (MK-2866)

Anabolic potency

High — +1.21 kg lean mass at 1 mg/day in 21 days

Highest claimed — no Phase 1 lean mass endpoint published

Moderate — multiple Phase 1/2/3 data; modest lean mass gains

Phase 1 human data

Yes — Basaria 2013; n=76; 0.1-1 mg/day; 21 days

Yes — LoRusso 2022; n=22; therapeutic doses in breast cancer patients

Extensive — multiple Phase 1/2/3 trials across cachexia, muscle wasting, cancer

Best Phase 1 dose

1 mg/day for 21 days (no SAEs)

Therapeutic oncology doses (SAEs: 59% elevated AST)

Up to 3 mg/day in longest Phase 2 trials without major SAE

Hepatotoxicity signal

One published case (ACG 2020); smaller series than RAD-140

Six or more published cases including near-transplant severity; Phase 1 trial 59% elevated AST

Several case reports; smaller series; generally lower severity signal

HPTA suppression

Moderate — dose-dependent; documented in Phase 1; significant at community doses

Significant — consistent community reports of near-zero testosterone

Mild to moderate — less suppressive at typical doses than LGD-4033 or RAD-140

Half-life

24-36 hours; once daily

~20 hours; once daily

24-36 hours; once daily

WADA status

S1.2 absolute ban

S1.2 absolute ban

S1.2 absolute ban

Doping violations

Multiple — Canelo Álvarez; NRL players; tennis; track & field

Some community reports; fewer high-profile athletic cases

Jonas Brodin (NHL); other athlete cases

PCT requirement

Yes — SERM PCT after every cycle

Yes — SERM PCT after every cycle

Mild cycles sometimes PCT-free; longer cycles require PCT

• What is the safety profile of LGD-4033 at community doses (5-20 mg/day) for 6-8 weeks? No clinical trial has studied this dose range; the Phase 1 maximum was 1 mg/day.
• Will Viking Therapeutics advance VK5211 to Phase 3 for hip fracture or another indication? The Phase 2 was positive but no Phase 3 has been announced; without a Phase 3, the compound is unlikely to achieve regulatory approval.
• What is the dose-response for hepatotoxicity in LGD-4033? One case occurred at 10 mg/day; is there a dose below which hepatotoxicity risk is minimal (as the Phase 1 at 1 mg suggests) or does the risk exist at any dose above a threshold?
• Does the lean mass gain from LGD-4033 persist after cycling off, or does it regress similarly to natural androgen-driven muscle gain? The community expectation is retention; the mechanistic prediction is variable.

Basaria S, Collins L, Dillon EL, et al. (2013). The Safety, Pharmacokinetics, and Effects of LGD-4033, a Novel Nonsteroidal Oral, Selective Androgen Receptor Modulator, in Healthy Young Men. Journals of Gerontology: Series A. 68(1):87-95. doi:10.1093/gerona/gls078. [The primary Phase 1 RCT; n=76; 0.1-1 mg/day; 21 days; +1.21 kg lean mass at 1 mg; no liver enzyme changes; dose-dependent HPTA suppression; foundational clinical data.]

Viking Therapeutics. (2018). VK5211, a Novel Selective Androgen Receptor Modulator (SARM), Significantly Improves Lean Body Mass in Hip Fracture Patients: Results of a 12 Week Phase 2 Trial. Plenary oral presentation at ASBMR Annual Meeting. [Phase 2 VK5211/LGD-4033 in hip fracture elderly patients; significant lean mass improvement; no drug-related SAEs; most advanced clinical development data for the compound.]

Ligandrol (LGD-4033)-Induced Liver Injury. (2020). ACG Case Reports Journal. 7(6):e00421. [Only published DILI case for LGD-4033; 10 mg/day for 2 weeks; jaundice; resolved after stopping; notes that 10 mg = 10-100x the Phase 1 doses; key safety reference for community users at higher doses.]

LGD-4033 has the strongest clinical trial foundation of any community SARM — and the most important caveat about that foundation: the trials were conducted at a fraction of community doses.

The honest summary: LGD-4033 produced an impressive lean mass result in Phase 1 (+1.21 kg at 1 mg/day in 21 days), demonstrated lean mass improvement in elderly hip fracture patients in Phase 2, has a documented and well-characterized pharmacokinetic profile, and showed no serious adverse events in the clinical trials at 0.1-1 mg/day. It also consistently suppresses the HPTA in a dose-dependent fashion, has at least one published DILI case at community doses (10 mg/day), has generated multiple high-profile athlete doping violations, and is used by the community at doses 5-20x higher than the maximum clinical dose for 2-3x longer durations. The risk-benefit calculation for LGD-4033 at community doses cannot be derived from the clinical trial data — the dose gap is too wide. What the clinical data establishes is that the compound's mechanism works (lean mass increases at 1 mg/day) and that the compound is safe at very low doses. What happens at 5-20 mg/day is extrapolated, not demonstrated.