RAD-140 (Testolone) vs YK-11

Mechanism

RAD-140 is a potent nonsteroidal SARM with high oral bioavailability and selectivity for muscle and bone AR over prostate. It acts as a full agonist at the AR in muscle tissue, promoting nitrogen retention and protein synthesis via mTOR/p70S6K pathway activation. RAD-140 also demonstrates neuroprotective properties, acting against beta-amyloid-induced neurotoxicity through AR-mediated MAPK/ERK signaling. Preclinical data show greater anabolic potency than testosterone propionate at equivalent doses with significantly reduced prostate stimulation.

Standard Dosing

Research indicates 10-20 mg daily orally for 8-12 weeks. Phase 1 clinical trial (oncology) identified 100 mg as the maximum tolerated dose.

Timing

Once daily, consistent timing. Very long half-life (~60 hours) means stable plasma levels even with once-daily dosing. Morning preferred.

Cycle Duration

8-12 week cycles. PCT mandatory due to significant HPG axis suppression.

Side Effects

• Significant testosterone suppression
• Hepatotoxicity (multiple published case reports of drug-induced liver injury)
• HDL suppression and LDL elevation
• Aggression and mood changes
• Hair shedding (androgenic effect despite 'selective' designation)
• Insomnia
• Headache

Contraindications

• Pre-existing liver disease
• Androgen-sensitive cancers
• Cardiovascular disease (LDL elevation concern)
• Pregnancy and breastfeeding
• Individuals under 21
• Athletes subject to anti-doping testing

Best Stacking Partners

Mechanism

YK-11 is a synthetic steroidal compound classified as a gene-selective partial agonist of the androgen receptor. Uniquely among SARMs, YK-11 does not induce the N/C terminal interaction of the AR required for full transcriptional activation, instead selectively activating a subset of AR-dependent genes. Its primary distinguishing mechanism is potent induction of follistatin expression, which directly antagonizes myostatin — a key negative regulator of skeletal muscle mass. This dual action (partial AR agonism + myostatin inhibition via follistatin) theoretically provides anabolic stimulus beyond what full AR agonists alone can achieve.

Standard Dosing

Research indicates 5-15 mg daily orally for 6-8 weeks. No human clinical trials exist — all dosing data is anecdotal.

Timing

Split into 2 daily doses (morning and evening) due to presumed short half-life (~6-10 hours based on structural analysis). Consistent timing essential.

Cycle Duration

6-8 week cycles maximum. PCT strongly recommended. Avoid extended use due to unknown long-term safety profile.

Side Effects

• Testosterone suppression (expected — steroidal compound)
• Hepatotoxicity (17-alpha-alkylated structure implies liver toxicity risk)
• Joint pain and tendon issues (anecdotal — possibly from DHT-like drying effects)
• Hair loss (steroidal androgenic effects)
• Aggression
• Unknown long-term effects (no human studies)

Contraindications

• Pre-existing liver disease
• Androgen-sensitive cancers
• Cardiovascular disease
• Pregnancy and breastfeeding
• Individuals under 21
• Anyone unwilling to accept research chemical risk with zero human clinical data

Best Stacking Partners