RAD-140

RAD-140 is a nonsteroidal selective androgen receptor modulator (SARM) ^[1]. SARMs are synthetic molecules that act on the androgen receptor, the same receptor targeted by testosterone, but are engineered to be tissue-selective, favouring anabolic effects in muscle and bone over the broader effects of steroids ^[1]. Chemically RAD-140 is an oxadiazole derivative with the formula C20H16ClN5O2, and it was designed to be potent and well absorbed when taken by mouth ^[1]. It is also known by the name testolone and has more recently been assigned the drug name vosilasarm.

The compound was discovered and developed by the pharmaceutical company Radius Health, which reported its design and preclinical testing around 2010, and it later passed into the hands of another developer ^[1]. It was initially of interest for anabolic uses such as combating the muscle loss of cachexia and for hormone-related conditions, and its development subsequently focused on androgen-receptor-positive breast cancer, where activating the androgen receptor can oppose estrogen-driven tumour growth ^[1]. Throughout this history RAD-140 has remained an investigational agent; it has not been approved by any medicines regulator for use in people.

Preclinical studies in animals and cells showed that RAD-140 behaves as an anabolic androgen, building muscle and bone ^[1]. Longer-term animal research, however, has raised concerns: a study in aging mice found that months of RAD-140 did not improve muscle strength and instead increased frailty and the risk of death compared with untreated animals ^[2]. Human data are very limited, confined largely to early-stage cancer trials. Outside of research, RAD-140 is widely sold over the internet as a bodybuilding and performance supplement under names such as Testolone, often in products of uncertain quality and purity ^[3]. This unsupervised use has been linked in medical case reports to serious harm, including drug-induced liver injury and acute inflammation of the heart muscle ^[3].

RAD-140 is not an approved medicine and is not a legal dietary supplement ingredient; regulators including the United States Food and Drug Administration have warned that SARMs are unapproved drugs and have cautioned against their sale in supplement form ^[3]. The World Anti-Doping Agency prohibits SARMs, including RAD-140, in and out of competition, and athletes have tested positive for it ^[1]. Because it is sold through unregulated channels, users cannot be sure what a given product actually contains ^[3].

RAD-140 suppresses the body's own testosterone production (HPTA suppression), and misuse has been linked to liver injury, including published case reports of drug-induced hepatitis that resolved after stopping, as well as cardiovascular strain. It is not approved for human use and is banned in sport. It is sold strictly as a research chemical.

RAD-140 (testolone) is an investigational selective androgen receptor modulator with no approved label and no formal pharmacokinetic drug-drug interaction studies. Its principal documented safety signal is hepatotoxicity; multiple published case reports describe drug-induced liver injury with cholestatic or mixed patterns after RAD-140 use, so concurrent use of other hepatotoxic agents is a theoretical additive concern. As an androgen receptor agonist it may also theoretically potentiate the effect of warfarin and reduce insulin or oral hypoglycemic requirements, effects that are established for approved anabolic-androgenic steroids but not specifically demonstrated for RAD-140. No CYP inhibition or induction interaction has been characterized in humans. This is research information, not medical advice.

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RAD-140 was discovered by the pharmaceutical company Radius Health and first described in the scientific literature in 2011, when its selective androgen receptor modulator profile and its ability to build muscle and bone in animal models were characterized. It was advanced as a candidate for conditions involving muscle wasting, and its capacity to suppress androgen-receptor-positive breast cancer cells later prompted interest in oncology, leading to early-phase clinical evaluation in hormone-receptor-positive breast cancer. Despite this development history, RAD-140 has never received regulatory approval for any indication and remains investigational. It became widely available through the online research-chemical market, where it is used for physique and performance purposes well outside its intended clinical context.

Within the SARM community RAD-140 is regarded as one of the more potent options for lean-mass gains, and its clean anabolic reputation is part of what keeps it in demand. That enthusiasm is best paired with the documented caveats: it is banned in sport by the World Anti-Doping Agency, and a growing series of published case reports links it to cholestatic drug-induced liver injury that can be severe, though generally reversible after discontinuation. Because human safety and efficacy data remain limited to preclinical work and case reports rather than controlled trials, honest discussion treats it as a compound of real interest whose long-term risk profile is still being defined. Interest in it as a research tool and as a template for future selective anabolics remains genuine and active.