RAD-140 and LGD-4033: Two Benchmarks in SARM Research
Among all characterized selective androgen receptor modulators, RAD-140 (Testolone) and LGD-4033 (Ligandrol) are consistently cited as the two most potent. Both demonstrate strong anabolic activity in rodent models and early human studies, but they differ in meaningful ways that influence research design choices. This article examines those differences in detail.
Receptor Binding and Tissue Selectivity
LGD-4033 binds the androgen receptor with high affinity (Ki ~1 nM) and acts as a full agonist in muscle and bone tissue. Its selectivity ratio over prostate tissue is substantial but not as extreme as that of RAD-140, which has been characterized with an anabolic-to-androgenic ratio exceeding 90:1 in the levator ani model. For researchers studying the upper limit of muscle-selective androgen signaling, RAD-140 is often the preferred tool compound.
Human Clinical Data
LGD-4033 has the more extensive human dataset. A Phase 1 dose-escalation trial in 76 healthy men demonstrated dose-dependent increases in lean body mass, reduced total testosterone, and suppressed SHBG — with recovery to baseline within weeks of cessation. RAD-140 has been evaluated in a Phase 1 trial in ER+/AR+ breast cancer patients, making its human safety profile somewhat better characterized in a clinical context than many other SARMs. For researchers who value human data when selecting comparators, LGD-4033 remains the standard for healthy-subject anabolic endpoints, while RAD-140 carries unique relevance in oncology-adjacent research.
Study Design Considerations
When designing muscle-wasting intervention studies in rodents, researchers often use LGD-4033 as the primary SARM arm due to its broader published dose-response characterization. RAD-140 is preferred when the research question centers on maximizing tissue selectivity or when an oncology context is relevant. Both compounds are routinely studied alongside MK-677 (Ibutamoren) to examine dual-axis anabolic effects, and alongside GW501516 (Cardarine) or SR9009 when metabolic endpoint data is also required.
For studies focused on milder AR agonism, MK-2866 (Ostarine) remains the reference compound, given its status as the SARM with the most published human trial data overall.
Available Research Formulations
See also our full RAD-140 research guide. All products are for laboratory research only.
