Overview
Testolone is a selective androgen receptor modulator (SARM) — a class of compounds that selectively bind to androgen receptors in muscle and bone tissue. Selective androgen receptor modulator.
With a half-life of ~2.5 days (60 hours), Testolone supports less frequent dosing schedules. Taken orally, it has a bioavailability of approximately 95% via its primary route.
Half-life approximately 60 hours. Long half-life supports once-daily dosing. High oral bioavailability. One-compartment model. Not FDA-approved for human use.
Mechanism of Action
Testolone's pharmacological activity involves the following key pathways:
Selective Receptor Binding
Testolone is designed to selectively bind to androgen receptors in muscle and bone tissue, with reduced activity in other androgen-sensitive tissues.
Tissue Selectivity
The selectivity of Testolone is achieved through differential coactivator recruitment — the compound activates different downstream pathways depending on the tissue type.
Dosing Protocols
The following protocols represent commonly observed dosing patterns. These are observational summaries, not recommendations.
Dose
10 mg/day
Route
Oral
Frequency
Every other day
Duration
8-12 weeks
Dose
25 mg/day
Route
Oral
Frequency
Every other day
Duration
8-12 weeks
Frequently Asked Questions
What is RAD-140 (Testolone) and how does it work?
RAD-140 (Testolone) is a non-steroidal selective androgen receptor modulator (SARM) developed for potential applications in muscle wasting and breast cancer. It selectively activates androgen receptors in muscle and bone tissue, promoting anabolic effects while demonstrating reduced androgenic activity in other tissues. Preclinical data shows it stimulates muscle weight increases at lower doses than those required for prostate stimulation.
What is the half-life of RAD-140?
RAD-140 has a reported half-life of approximately 60 hours in humans, though a phase 1 clinical study observed a half-life closer to 45 hours. This extended half-life supports once-daily dosing and results in significant accumulation over the first 1–2 weeks of consistent use. Steady-state plasma concentrations are typically reached within 10–13 days.
How long does RAD-140 take to show effects?
Increased training intensity and strength are commonly reported within the first 1–2 weeks as plasma concentrations accumulate. Noticeable changes in muscle fullness and body composition are typically observed by weeks 3–4. The full extent of effects on lean mass and strength is generally reported over 8–12 weeks of consistent dosing.
Does RAD-140 suppress natural testosterone?
RAD-140 is commonly associated with significant suppression of natural testosterone production, even during shorter cycles of 6–8 weeks. Suppression effects are reported to be more pronounced at higher doses and longer cycle durations. Post-cycle therapy is frequently observed in community protocols, typically beginning approximately 12 days after the last dose to account for the compound's long half-life.
What are the common side effects of RAD-140?
Commonly reported effects include headaches, nausea, fatigue, and changes in blood pressure, which are generally mild and transient. Elevations in liver enzymes (AST/ALT) have been observed in some cases. Androgenic effects such as acne and hair shedding are occasionally reported in predisposed individuals. Testosterone suppression symptoms including decreased libido and reduced energy are frequently noted.
Can RAD-140 be stacked with other SARMs?
RAD-140 is frequently stacked with MK-677 (Ibutamoren) in community protocols, as MK-677 provides complementary GH secretion without additional androgen receptor activation. Stacking with other suppressive SARMs like LGD-4033 is observed but carries increased suppression and liver strain considerations. Each additional compound in a stack increases the cumulative physiological load.