RAD-140 Overview, Dosing & Safety | Peptide Database

RAD-140 (Testolone)

Selective Androgen Receptor Modulator | Investigational SARM

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RAD-140 (Testolone) is a nonsteroidal investigational selective androgen receptor modulator (SARM) originally developed by Radius Health, Inc. for the potential treatment of muscle wasting conditions and hormone receptor-positive breast cancer. It was designed to provide the anabolic benefits of testosterone, specifically increased lean muscle mass and bone density, while minimizing androgenic side effects in tissues such as the prostate and skin. RAD-140 has demonstrated a high degree of tissue selectivity in preclinical models, with an anabolic-to-androgenic ratio substantially greater than that of testosterone. It entered Phase 1 clinical trials for metastatic breast cancer (ER+/HER2-) and has shown preliminary safety and tolerability in that context. However, RAD-140 is not approved for any medical use by any regulatory agency. It remains a research compound, and its widespread use in performance and physique enhancement contexts is based almost entirely on preclinical data and anecdotal reports rather than completed clinical trials for those indications.

RAD-140 binds to the androgen receptor (AR) with high affinity and selectivity, functioning as a full agonist in muscle and bone tissue while exhibiting minimal agonist activity in the prostate and other androgen-sensitive tissues. This tissue selectivity is achieved through differential cofactor recruitment: upon binding to the AR, RAD-140 induces a conformational change that favors interaction with coactivators predominantly expressed in skeletal muscle and bone, rather than those prevalent in prostate or sebaceous glands. In preclinical studies, RAD-140 demonstrated potent anabolic effects on levator ani muscle mass comparable to testosterone, while showing significantly less stimulation of prostate weight. RAD-140 also crosses the blood-brain barrier and has demonstrated neuroprotective properties in in vitro models, reducing cell death caused by apoptotic insults in hippocampal neurons. At the molecular level, it activates AR-dependent gene transcription pathways involved in protein synthesis, nitrogen retention, and satellite cell proliferation in skeletal muscle. Importantly, RAD-140 does not undergo aromatization to estrogen and is not a substrate for 5-alpha reductase, meaning it does not produce estrogenic or DHT-mediated side effects. However, like all exogenous AR agonists, it suppresses endogenous testosterone production through negative feedback on the hypothalamic-pituitary-gonadal (HPG) axis.

Molecular Data

Research Indications

RAD-140 has shown potent anabolic effects on skeletal muscle in preclinical models, with increases in lean body mass comparable to moderate doses of testosterone. Users report meaningful increases in lean mass over 8-12 week cycles at 10-20 mg/day, though controlled human trial data for this indication is lacking.

Dose-dependent increases in strength have been reported anecdotally and are consistent with the compound's mechanism of action as a potent AR agonist in skeletal muscle. Strength gains are typically noticed within 2-4 weeks of starting a cycle.

The combination of anabolic activity without estrogenic water retention makes RAD-140 a compound of interest for simultaneous fat loss and lean mass gain. Preclinical data supports a favorable shift in body composition, though human data is limited.

RAD-140 has entered Phase 1 clinical trials for the treatment of ER+/AR+/HER2- metastatic breast cancer. The rationale is that AR activation can suppress estrogen-driven tumor growth in AR-positive breast cancers. Early results demonstrated tolerability and preliminary signals of anti-tumor activity.

Originally developed for conditions involving muscle wasting (cachexia, sarcopenia, age-related muscle loss). Preclinical data supports the potential to preserve or restore muscle mass in catabolic states, but no human efficacy trials have been completed for this indication.

In vitro studies have shown that RAD-140 protects hippocampal neurons from kainate-induced excitotoxicity and beta-amyloid-induced cell death, suggesting potential relevance to neurodegenerative diseases. This remains a preclinical observation only.

Dosing Protocols

RAD-140 is administered exclusively via the oral route. It is available as a liquid solution (typically dissolved in a carrier such as PEG-400 or ethanol) or in capsule form from research chemical suppliers. The compound has high oral bioavailability due to its nonsteroidal structure and resistance to first-pass metabolism. Its long half-life of approximately 60 hours allows for once-daily dosing with stable plasma concentrations achieved within 1-2 weeks.

Research Dose - Conservative

10 mg/day

Once daily

Oral (liquid or capsule)

Research Dose - Moderate

15-20 mg/day

Research Dose - Upper Range

20-30 mg/day

Interactions

What to Expect

Side Effects & Safety

Common Side Effects

Testosterone suppression (dose-dependent, occurs in virtually all users by week 4-6)

Liver enzyme elevation (ALT, AST increases reported in clinical and anecdotal data)

Hair shedding (temporary, typically resolves after discontinuation)

Headaches (most common in the first 1-2 weeks, often transient)

Nausea (mild, usually with initial doses or on an empty stomach)

Lipid disruption (HDL suppression, LDL elevation)

Mild insomnia or sleep disturbance

Reduced libido and mood changes related to testosterone suppression

Stop Signs - Discontinue if:

Jaundice (yellowing of skin or eyes) indicating significant liver injury

Severe or persistent lethargy unresponsive to rest (may indicate profound hormonal suppression or liver stress)

Chest pain, tightness, or palpitations

Dark-colored urine (potential sign of liver damage or rhabdomyolysis)

Severe abdominal pain or persistent nausea/vomiting

Signs of allergic reaction: rash, swelling, difficulty breathing

Contraindications

Pre-existing liver disease or elevated liver enzymes at baseline

Hormone-sensitive cancers (prostate cancer, certain breast cancers not being treated under clinical supervision)

Pregnancy or potential pregnancy (teratogenic risk from androgen receptor agonism)

Breastfeeding

Age under 25 (incomplete endocrine system maturation and higher risk of HPG axis disruption)

Concurrent use of hepatotoxic medications without medical supervision

Known cardiovascular disease (insufficient safety data for this population)

Quality Checklist

Good Signs

Third-party lab tested with certificate of analysis (COA) showing purity above 98%

Clearly labeled with compound name, concentration, batch number, and expiration date

Solution is clear and free of particulate matter or discoloration

Sold as a research chemical with appropriate disclaimers (not marketed for human consumption)

Supplier provides HPLC or mass spectrometry verification of identity and purity

Warning Signs

No third-party testing or certificate of analysis available

Sold in pre-made capsules without verifiable dosing accuracy

Concentration claims that vary between batches from the same supplier

Marketed with explicit performance enhancement claims (regulatory red flag)

Unusually low pricing compared to established research chemical suppliers

Bad Signs

Cloudy, discolored, or precipitated solution indicating degradation or contamination

No labeling, incorrect labeling, or missing batch/lot information

Supplier has no verifiable reputation, reviews, or testing history

Product tested by independent labs showing underdosed, mislabeled, or contaminated contents

Contains unlisted active ingredients or adulterants (a documented problem in the SARM market)

Sold by a source that also sells controlled substances (legal risk indicator)

Frequently Asked Questions

Does RAD-140 actually spare the prostate like it claims, or will it cause the same problems as testosterone?

RAD-140's tissue selectivity means it stimulates muscle and bone more than prostate compared to testosterone, but it still suppresses testosterone and activates androgen receptors systemically. While prostate stimulation may be less than equivalent testosterone doses, it's not eliminated—monitor PSA during and after cycles.

How much testosterone suppression happens on RAD-140?

RAD-140 causes dose-dependent testosterone suppression typically visible by week 4-6, with users reporting 30-70% suppression by mid-cycle depending on dose and individual sensitivity. At 20mg/day, suppression is usually pronounced, making a low-dose testosterone base (100-150mg/week) common to maintain sexual function.

Is RAD-140 hepatotoxic like oral steroids?

RAD-140 produces liver enzyme elevation in some users, with documented cases of significant DILI (drug-induced liver injury). While not a 17-alpha-alkylated steroid, it carries hepatotoxicity risk that requires baseline and mid-cycle bloodwork. Liver support (TUDCA, NAC) is prudent at doses above 15mg/day.

How does RAD-140 compare to testosterone for muscle gains?

Preclinical data suggest RAD-140 is anabolically potent per milligram, comparable to moderate testosterone doses (400-600mg/week). However, anecdotal reports suggest real-world results are modest compared to high-dose testosterone stacks—the suppression of endogenous test without estrogenic support may limit net gains.

References

Demonstrated that RAD-140 is neuroprotective against kainate-induced excitotoxicity in hippocampal neurons in vitro and in vivo in male rats. RAD-140 was as effective as testosterone in reducing cell death, supporting potential applications in neurodegenerative disease.

Initial characterization of RAD-140 demonstrating high affinity and selectivity for the androgen receptor, potent anabolic activity on muscle tissue (levator ani muscle), and marked tissue selectivity with minimal stimulation of the prostate in preclinical models. Established RAD-140 as a lead SARM candidate for clinical development.

Phase 1 dose-escalation study in postmenopausal women with ER+/AR+/HER2- metastatic breast cancer. RAD-140 was generally well tolerated with manageable side effects including transient liver enzyme elevations. Preliminary evidence of anti-tumor activity was observed, supporting further clinical investigation.

Case series documenting clinically significant drug-induced liver injury (DILI) in individuals using SARMs including RAD-140. Patients presented with markedly elevated transaminases and cholestatic liver injury patterns, with recovery after discontinuation. Highlights the hepatotoxicity risk of unregulated SARM use.

Comprehensive review of SARM pharmacology, clinical development, and therapeutic potential. Discusses the mechanism of tissue selectivity, preclinical efficacy data for various SARMs including RAD-140, and the regulatory landscape. Notes that while SARMs show promise for muscle wasting and osteoporosis, no SARM has yet achieved regulatory approval.

Related Peptides

Enclomiphene is commonly used as part of post-cycle therapy (PCT) following RAD-140 cycles to restore endogenous testosterone production. Typical PCT protocol is 12.5-25 mg/day enclomiphene for 4-6 weeks starting 2-3 days after the last RAD-140 dose (accounting for its long half-life, a delayed start of 5-7 days may also be appropriate).

MK-677 (Ibutamoren) is frequently stacked with RAD-140. MK-677 increases growth hormone and IGF-1 through ghrelin receptor agonism, complementing the AR-mediated anabolic effects of RAD-140. The combination may enhance lean mass accrual, recovery, and sleep quality. MK-677 does not suppress testosterone, making it a useful adjunct during and after SARM cycles.

Disclaimer

This information is for educational and research purposes only. Consult a healthcare professional before use.