RAD-140 (Testolone): What the Research Actually Shows About This SARM

What Is RAD-140 and How Does It Work?

RAD-140, also called testolone, is a synthetic nonsteroidal compound that binds selectively to androgen receptors in muscle and bone tissue. The goal of selectivity is to produce anabolic effects similar to testosterone while reducing androgenic activity in the prostate, liver, and skin. Radius Health originally reported the compound in a 2010 patent application, and early preclinical data showed favorable anabolic-to-androgenic ratios compared with testosterone propionate in rodent models. [1]

Androgen receptors sit inside the cell nucleus. When an agonist binds, the receptor complex moves to DNA response elements and up-regulates genes controlling protein synthesis and satellite cell activation. RAD-140 acts as a full agonist in skeletal muscle and a partial agonist or antagonist depending on tissue context, which theoretically limits prostate enlargement and suppresses erythropoiesis less aggressively than exogenous testosterone.

That theoretical selectivity has not been confirmed in a large, well-controlled human trial. A Phase II study of RAD-140 in metastatic androgen-receptor-positive, HER2-negative breast cancer (NCT03088527) reported preliminary safety signals but has not produced peer-reviewed efficacy data at a sample size adequate to draw firm conclusions. [2] Animal models cannot reliably predict human pharmacokinetics or organ-specific off-target effects. The half-life of approximately 60 hours was extrapolated from primate studies. Human elimination data remain sparse and inconsistent across anecdotal reports.

What Does the Clinical Evidence Actually Show?

The clinical evidence for RAD-140 is thin. One Phase I dose-escalation trial in postmenopausal women with breast cancer (N=35) found that RAD-140 at 100 mg/day produced a partial response or stable disease in a subset of heavily pre-treated patients, but hepatotoxicity led to dose modifications in several participants. [3] No placebo-controlled muscle-building trial in healthy humans has been published in a peer-reviewed journal.

For context, compare this to testosterone enanthate, where decades of randomized data exist. The landmark Bhasin et al. NEJM trial (N=61) demonstrated that graded doses of testosterone (25 mg to 600 mg/week for 20 weeks) produced dose-dependent increases in fat-free mass of up to 7.9 kg versus 1.7 kg placebo. [4] RAD-140 has no equivalent dataset.

The table below summarizes where the most commonly discussed SARMs sit on the clinical-evidence ladder. This framework was developed by the HealthRX medical team to help clinicians and patients quickly assess regulatory and safety standing:

SARM Evidence Tier Framework (HealthRX Medical Team, 2025)

| Compound | Highest Phase Reached | Peer-Reviewed Human RCT | FDA Status | WADA | |---|---|---|---|---| | RAD-140 (testolone) | Phase II (breast cancer) | None (body composition) | Not approved | Banned | | Ostarine (MK-2866) | Phase II (muscle wasting) | 2 small RCTs | Not approved | Banned | | LGD-4033 (ligandrol) | Phase II | 1 small RCT | Not approved | Banned | | GW501516 (cardarine) | Phase I | None (abandoned) | Not approved | Banned | | SR9009 (stenabolic) | Preclinical only | None | Not approved | Banned |

Every compound in this table is classified by the World Anti-Doping Agency under the S1 Anabolic Agents category. [5]

RAD-140 Side Effects and Safety Signals

RAD-140 carries documented risks. Liver injury is the most concerning. The FDA published a safety communication in 2023 warning consumers about SARMs-containing products after multiple hospitalizations for drug-induced liver injury (DILI). [6] Case reports in peer-reviewed literature include acute cholestatic hepatitis following RAD-140 use. A 2020 case report in ACG Case Reports described a 49-year-old male who developed jaundice, pruritus, and an ALT of 1 to 652 U/L after six weeks of self-reported RAD-140 use at an unknown dose purchased online. [7]

Testosterone suppression is the second major concern. All SARMs that produce meaningful anabolic effects suppress the hypothalamic-pituitary-gonadal (HPG) axis to varying degrees. Small pharmacokinetic data sets suggest RAD-140 at doses used by recreational consumers (10 to 30 mg/day) can reduce serum LH and testosterone within four to eight weeks. Recovery after cessation varies. Some anecdotal reports suggest natural testosterone recovery of three to six months without post-cycle therapy, though no controlled study has characterized this timeline reliably.

Additional signals from case reports and preclinical data include:

• Elevated hematocrit (erythropoietic stimulation is lower than testosterone but not zero)
• Acne and androgenic alopecia in genetically predisposed individuals
• Cardiovascular lipid changes, specifically HDL reduction, seen with LGD-4033 at 1 mg/day in the only published human RCT [8]
• Mood changes and aggression, reported anecdotally but not quantified in controlled studies

The FDA's Center for Drug Evaluation and Research states clearly: "SARMs have not been approved by FDA and are associated with serious safety concerns, including potential to increase the risk of heart attack, stroke, and liver damage." [6]

How RAD-140 Compares to Ostarine (MK-2866)

Ostarine (MK-2866, enobosarm) is the most clinically studied SARM. GTx Inc. ran two Phase II randomized, double-blind, placebo-controlled trials (GHBP-0302 and GHBP-0303) in cancer patients with cachexia. Pooled data from these trials (N=159) showed that 3 mg enobosarm daily for four months increased lean body mass by 1.4 kg versus placebo at P<0.001. [9] A Phase III program for cancer cachexia ultimately failed to meet its co-primary endpoints, which is why no SARM has received FDA approval.

Compared to RAD-140, ostarine has a shorter estimated half-life (24 hours), a weaker anabolic signal per milligram in animal studies, and a marginally better documented safety profile in controlled human trials. HPG axis suppression is dose-dependent for ostarine as well. At 3 mg/day for 86 days, total testosterone decreased by approximately 12 to 18% from baseline in the GTx trials.

Neither compound is a legal substitute for physician-supervised testosterone replacement therapy in patients with confirmed hypogonadism. The Endocrine Society's 2018 Clinical Practice Guideline for testosterone therapy states that testosterone should be considered only in men with "unequivocally low serum testosterone concentrations and consistent symptoms." [10] That standard does not apply to research chemicals purchased without a prescription.

How RAD-140 Compares to LGD-4033 (Ligandrol)

LGD-4033, developed by Ligand Pharmaceuticals and later Viking Therapeutics, is the most potent SARM by anabolic signal in the compounds reviewed here. The single published placebo-controlled RCT in healthy men (Basaria et al., JAMA Internal Medicine, 2013; N=76) showed that LGD-4033 at 1 mg/day for 21 days increased lean body mass by 1.21 kg versus 0.03 kg placebo. [8] The effect was dose-dependent (doses tested: 0.1, 0.3, and 1 mg). Even at this low dose and short duration, HDL dropped by approximately 0.24 mmol/L and free testosterone was suppressed.

RAD-140 proponents claim a higher anabolic-to-androgenic ratio than LGD-4033 in rodent assays. Published human comparative data do not exist. Extrapolating rodent assay ratios to human body-composition outcomes is not valid methodology.

LGD-4033 has also been the subject of multiple doping control cases, including the suspension of professional athletes across multiple sports. The World Anti-Doping Agency added it to the Prohibited List in 2008.

Cardarine (GW501516): Not a SARM, and Not Safe

Cardarine (GW501516) is often grouped with SARMs in fitness circles, but the mechanism is entirely different. It is a PPARδ (peroxisome proliferator-activated receptor delta) agonist, not an androgen receptor agonist. GlaxoSmithKline abandoned GW501516 development in 2007 after rodent carcinogenicity studies showed rapid tumor development across multiple organ systems at doses extrapolated to human equivalents. [11]

The WADA Science Department issued a specific warning noting that cardarine caused cancer in animals "at all doses tested," including doses below those being used by recreational consumers at the time. [5] No human Phase II or Phase III trial has been completed. Using cardarine for any purpose in a human being is, by any reasonable clinical standard, unjustifiable given the carcinogenicity signal.

This compound is fundamentally different from RAD-140 in its risk profile. Suppression of the HPG axis is not the primary concern. Potential induction of malignancy is.

Stenabolic (SR9009): A Compound With No Human PK Data

SR9009, marketed as "stenabolic," is a REV-ERB agonist. It showed effects on circadian rhythm, mitochondrial biogenesis, and exercise capacity in mouse models published by the Scripps Research Institute. [12] The compound has near-zero oral bioavailability in rodents (estimated at less than 2%), which was why the original researchers used intraperitoneal injection in animal studies. No human pharmacokinetic trial has been published.

Oral SR9009 capsules sold online as a "research chemical" almost certainly do not deliver meaningful systemic concentrations. Any perceived effects are likely attributable to placebo response or co-administration of other compounds. The absence of human PK data makes it impossible to characterize an effective dose, a toxic dose, or a clearance timeline for drug testing purposes.

Legal Status and Anti-Doping Consequences

RAD-140 and all other SARMs are not controlled substances under the U.S. Controlled Substances Act in the way anabolic steroids are. However, the Designer Anabolic Steroid Control Act of 2014 expanded the definition of anabolic steroids and gave the DEA authority to schedule SARM-like compounds. Individual states may have additional restrictions.

In sport, the consequences are clear. The WADA Prohibited List (2024 edition) explicitly bans all SARMs under Section S1.2 (Other Anabolic Agents), with no threshold. [5] A single positive test can result in a four-year suspension under the World Anti-Doping Code for a first violation with no prior record. Athletes at the collegiate level fall under NCAA Drug Testing Policy, which also bans SARMs.

Consumers who purchase these compounds online face additional risk from product adulteration. An independent laboratory analysis study published in JAMA found that among 44 products sold as SARMs online, only 52% contained a SARM as labeled, 39% contained another unapproved drug, and 25% contained substances not listed on the label at all. [13]

What Are the Legal, Physician-Supervised Alternatives?

For patients with documented hypogonadism (total testosterone below 300 ng/dL on two morning measurements, confirmed by an endocrinologist or urologist), FDA-approved testosterone replacement therapy options include:

• Testosterone cypionate or enanthate (injectable, generic, well-studied)
• Testosterone undecanoate (Aveed, 750 mg IM every 10 weeks after loading)
• Transdermal testosterone (AndroGel, Testim, various generic 1% or 1.62% gels)
• Testosterone pellets (Testopel, subcutaneous implant, 3 to 6 month duration)

For patients interested in body composition and not hypogonadal, evidence-based interventions with a safety record include progressive resistance training protocols, optimized dietary protein (1.6 to 2.2 g/kg/day per the International Society of Sports Nutrition position stand), creatine monohydrate (3 to 5 g/day, supported by a 2017 meta-analysis of 22 RCTs showing 1.37 kg greater lean mass gain versus placebo), and sleep optimization.

GLP-1 receptor agonists such as semaglutide (Ozempic, Wegovy) are FDA-approved and have strong evidence for fat mass reduction. In STEP-1 (N=1,961), semaglutide 2.4 mg weekly produced 14.9% mean body weight loss at 68 weeks versus 2.4% placebo (P<0.001). [14] These medications address fat loss as a component of body composition remodeling in a legal, monitored setting.

No physician at HealthRX prescribes RAD-140, ostarine, LGD-4033, cardarine, or SR9009. If a telehealth platform offers these compounds by prescription, that represents a significant departure from standard of care.