RAD-150

RAD-150 (TLB-150 Benzoate) is the benzoate-esterified prodrug of RAD-140 (testolone). Once esterases cleave the benzoate group, the liberated active moiety behaves as a potent, non-steroidal, tissue-selective androgen receptor (AR) agonist — the same ligand class that made RAD-140 a staple of the SARM category. The ester is a pharmacokinetic modification, not a pharmacodynamic one: receptor target, selectivity profile, and downstream gene programs are inherited directly from the parent compound.

Selective Androgen Receptor Agonism#

The active ligand binds the AR ligand-binding domain with high affinity and acts as a tissue-selective agonist — strongly anabolic in skeletal muscle and bone, markedly less active in prostate and seminal-vesicle tissue compared with testosterone. This is the defining feature of the SARM class and the basis for the ~90:1 anabolic-to-androgenic ratio reported for the parent compound.

"RAD140 is a potent, orally bioavailable, nonsteroidal SARM with high AR affinity (Ki ≈ 7 nM) and robust anabolic activity in vivo, with dose-dependent increases in lean muscle mass and only modest stimulation of prostate tissue." — Miller CP et al., ACS Medicinal Chemistry Letters, 2011

Practically, this is why RAD-150 produces RAD-140-like lean-mass and strength outcomes without the full androgenic burden of exogenous testosterone — less prostate load, less direct DHT-pathway aggression, but still meaningful suppression of the HPTA because AR agonism in the hypothalamus and pituitary doesn't care whether the ligand is steroidal.

Nuclear Translocation and Myogenic Gene Programs#

Once the ligand engages AR in muscle tissue, the receptor-ligand complex dissociates from heat-shock chaperones, dimerizes, translocates to the nucleus, and binds androgen response elements (AREs) in target gene promoters. The transcriptional program that follows is what actually drives hypertrophy.

"Ligand-bound androgen receptor translocates to the nucleus and regulates gene expression programs that include IGF-1, follistatin, and hepatocyte growth factor, driving myogenic satellite cell engagement and muscle recovery." — Serra C et al., Nuclear Receptor Signaling, 2013

Three downstream outputs matter most to the reader:

• IGF-1 upregulation — local (intramuscular) IGF-1 drives protein synthesis and satellite cell proliferation.
• Follistatin upregulation — antagonises myostatin, removing a brake on hypertrophy.
• HGF release — activates quiescent satellite cells, which fuse into existing myofibres and donate their nuclei, raising the ceiling on muscle fibre growth.

This is the same myogenic pathway exploited by testosterone and by other SARMs; RAD-150's selectivity just means the signal is delivered preferentially to muscle.

Benzoate Ester — A Pharmacokinetic Bolt-On#

The benzoate modification doesn't alter receptor binding. What it changes is metabolic stability and systemic exposure. Esterases progressively hydrolyse the benzoate group, releasing the active ligand over an extended window. The community/vendor-reported 40–48 hour half-life (unverified in peer-reviewed literature) is roughly double the ~16–20 hour half-life reported for RAD-140 in preclinical PK.

The practical consequences:

Steadier plasma levels mean fewer peak-trough oscillations — users describe this as a "smoother" feel, which is plausible on PK grounds rather than pure marketing. The flip side: the longer exposure window extends AR engagement, and class-effect issues (suppression, lipid shifts, hepatic strain) accumulate on the same timeline.

Class-Effect Hepatic Signal#

SARMs are not 17α-alkylated orals, and RAD-150 is not structurally hepatotoxic in the way that anadrol or superdrol are. The liver signal reported across SARM users is instead a consequence of excessive AR engagement itself.

"Cholestatic liver injury after SARM use is believed to be a class effect related to excessive androgen receptor engagement, not due to a direct hepatotoxic metabolite." — Hoofnagle JH, LiverTox, 2025

This reframes how the compound should be run: the risk is dose- and duration-driven, not "toxic molecule" driven. Keeping dose in the 5–15 mg/day band, capping cycles at 8 weeks, and pulling mid-cycle LFTs keeps the AR-engagement load inside the range where the hepatic signal stays subclinical for the overwhelming majority of users.

HPTA Suppression via Central AR Agonism#

The same AR agonism that grows muscle in the periphery also shuts down the hypothalamic-pituitary-gonadal axis centrally. AR activation in the hypothalamus suppresses GnRH pulses; downstream, LH and FSH fall, and endogenous testosterone production with them.

Documented in SARM user cohorts:

"Performance enhancement, lean mass gains and moderate suppression of endogenous hormonal axes were repeatedly documented in recreational and athletic SARM use, with RAD-class SARMs among the most frequently reported." — Vasireddi N et al., The American Journal of Sports Medicine, 2025

This is the mechanistic reason PCT is required on RAD-150, not optional. The ester's extended half-life is also why SERM-based PCT is initiated ~72 hours after the final dose rather than the next day — starting nolvadex or clomid while AR is still saturated with ligand wastes SERM exposure on a receptor population that's already occupied.

Put together: the ligand drives satellite-cell-mediated hypertrophy in muscle, suppresses the HPTA centrally, leaves prostate tissue relatively quiet, and — courtesy of the benzoate ester — does all of this on a once-daily, steady-state PK curve that makes the compound clean to run but unforgiving about cycle length.

Common (most users)#

• HPTA suppression — near-universal above 10mg/day. Total testosterone, free T, LH, and FSH trend down by week 4. Mitigation: cap cycles at 8 weeks, run a standard SERM PCT, and do not bridge back-to-back cycles without recovery bloodwork.
• HDL suppression — the most consistent lipid finding across SARM users. Mitigation: baseline + week-4 lipid panels, citrus bergamot or low-dose fish oil on cycle, keep saturated fat moderate, and avoid stacking with orals that hammer HDL further (stanozolol, anavar).
• Mild lethargy or flat mood late in cycle — usually tracks with suppressed endogenous test and low estradiol by weeks 6–8. Mitigation: accept the taper, keep cycle at 8 weeks max, and resist the urge to redose harder.
• Water retention and mild BP elevation — common, dose-dependent. Mitigation: home BP cuff, sodium control, low-dose tadalafil (2.5–5mg) if BP drifts above ~135/85.
• Libido dip in weeks 5–8 — secondary to suppression + low estradiol. Mitigation: hold the course, PCT fixes it. Tadalafil helps with erectile quality in the interim.
• Hair shedding (in predisposed users) — RAD-class SARMs bind AR in scalp tissue. Mitigation: topical RU58841 on cycle; oral finasteride/dutasteride as a longer-term background if conception isn't near-term.

"Running 10mg RAD-150 daily for 8 weeks with pre, mid, and post bloodwork. Mild testosterone suppression and minor lipid shifts at this dose, side effects were relatively mild and manageable through cycle support." — Reddit: r/SARMs (2024)

Uncommon (dose-dependent or individual)#

• Elevated AST/ALT — shows up more frequently above 15mg/day or past 8 weeks. Check mid-cycle LFTs; if ALT drifts above ~2× ULN, drop dose or discontinue.
• Aggression, irritability, sleep disturbance — reported more on higher-dose runs (15–30mg). Back off the dose before reaching for a sleep aid.
• Joint dryness / tendon discomfort — tracks with low estradiol late in cycle. Not a reason to panic; resolves post-PCT. Hydration and fish oil help.
• Headaches and mild visual disturbance — rare, usually associated with BP elevation or dehydration. Check BP first.
• LDL and triglyceride drift — less consistent than HDL drop but happens. Mid-cycle lipid panel catches it.

Rare but serious#

• Cholestatic liver injury — documented across the SARM class, more prevalent at recreational doses well above clinical-trial dosing. Warning signs: dark urine, pale stool, jaundice, right-upper-quadrant pain, severe itching. Discontinue immediately and get LFTs + bilirubin if any of these appear.

"Cholestatic liver injury after SARM use is believed to be a class effect related to excessive androgen receptor engagement, not due to a direct hepatotoxic metabolite." — Hoofnagle JH, LiverTox (2025)

• Severe lipid shift with cardiovascular risk — HDL crashes below ~20 mg/dL combined with BP elevation are a stop signal, not a "push through" signal.
• Prolonged suppression / failure to recover — rare after a single 8-week run at sensible doses, more plausible after stacking multiple SARMs or running past cycle limits. A full hormonal panel at 4 weeks post-PCT confirms recovery; if LH/FSH and total T have not returned to baseline, an endocrinology workup is warranted rather than another cycle.
• Counterfeit / mislabeled product causing unexpected effects — the black-market SARM supply is unreliable. LiverTox explicitly flags label inaccuracy for this class. Batch-specific third-party COAs are the minimum sourcing standard.

Hard contraindications#

• Pre-existing hepatic dysfunction or elevated baseline LFTs — do not run RAD-150. The ester extends AR exposure and the class is associated with cholestatic injury.
• Untreated dyslipidemia or hypertension — resolve these with lifestyle, a statin, or an antihypertensive before any SARM cycle. Stacking AR agonism on top of already-poor lipids is how users end up with a cardiology appointment.
• Heavy alcohol intake during the cycle — compounds hepatic risk for no benefit.
• Female users — RAD-150 is not appropriate. AR agonism is the mechanism, and the 40–48 hour half-life eliminates the ability to discontinue quickly at first sign of virilization (voice deepening, clitoral hypertrophy, hirsutism — all potentially irreversible).
• Near-term conception plans (male or partner) — SARMs suppress spermatogenesis. Fertility returns after recovery but should not be assumed immediate; plan 3–6 months of post-PCT clearance before attempting conception.
• Pregnancy or potential pregnancy — AR agonists are contraindicated; virilization of a female fetus is a known risk of androgen exposure.
• Tested competition — RAD-140 and analogs are named on the WADA prohibited list (S1.2, Other Anabolic Agents). The benzoate ester does not change this.

Gender and PCT considerations#

Female users: RAD-150 is not a women's compound. The long half-life is the disqualifier — unlike short-acting orals that can be stopped the moment virilization signs appear, the ester keeps AR engaged for days after the last dose. Women wanting a SARM-class compound look to lower-androgenicity options (ostarine at ≤10mg) with eyes open, not RAD-150.

PCT protocol: A standard 4-week SERM protocol is the community default — nolvadex 20/20/10/10 or clomid 25/25/12.5/12.5. PCT initiation is delayed ~3 days after the last dose to allow ester clearance; starting while AR is still saturated wastes SERM exposure. Recovery bloodwork at 4 weeks post-PCT (total T, free T, LH, FSH, estradiol, lipids, LFTs) confirms the cycle closed cleanly.

Bloodwork cadence — non-negotiable: baseline, mid-cycle (week 4: LFTs, lipids, total T, LH/FSH, estradiol), and 4 weeks post-PCT. Running without at least pre/post panels is the single most common pitfall and the one that turns a manageable side-effect profile into a problem discovered too late.

"Performance enhancement, lean mass gains and moderate suppression of endogenous hormonal axes were repeatedly documented in recreational and athletic SARM use, with RAD-class SARMs among the most frequently reported." — Vasireddi N, et al., The American Journal of Sports Medicine (2025)