RAD-140 Dosage Protocol Guide 2026: Testolone Research, Mechanisms & Safety Data

# RAD-140 (Testolone) Dosage Research Protocol Guide (2026)

> Research Use Only (RUO) Disclaimer: RAD-140 (Testolone) is not approved by the FDA or any regulatory authority for human use. It is classified as a research chemical. All information below is intended strictly for scientific research purposes. Not for human consumption, therapeutic use, or self-administration.

What Is RAD-140?

RAD-140, the research name for Testolone (IUPAC: 2-chloro-4-[[(1R,2S)-1-[5-(4-cyanophenyl)-1,3,4-oxadiazol-2-yl]-2-hydroxypropyl]amino]-3-methylbenzonitrile), is a non-steroidal selective androgen receptor modulator (SARM) developed by Radius Health and first described in scientific literature in 2010. It was originally developed as a potential treatment for muscle wasting and breast cancer, leveraging the tissue-selective properties of SARMs to separate anabolic effects in muscle and bone from androgenic effects in reproductive tissues.

RAD-140 is among the most potent SARMs studied by researchers, with in vitro and in vivo data demonstrating a remarkably high anabolic-to-androgenic ratio — a key metric researchers use to evaluate the tissue selectivity of androgen receptor modulators.

Mechanism of Action

Like all SARMs, RAD-140 binds to the androgen receptor (AR) and induces a conformational change in the receptor's ligand-binding domain. This conformational change determines which co-activators and co-repressors are recruited — and therefore which genes are transcribed. The SARM's chemical structure dictates this tissue-specific co-regulator recruitment profile.

In muscle and bone tissue: RAD-140 recruits anabolic co-activators, driving gene expression for muscle protein synthesis, IGF-1 production, and bone matrix formation — similar to testosterone.

In prostate and hair follicle tissue: The different co-regulator landscape in these tissues means RAD-140 does not strongly activate the same transcription pathways that cause androgenic side effects (prostate enlargement, DHT-mediated hair follicle miniaturization).

Key pharmacological properties of RAD-140:

• •Anabolic-to-androgenic ratio: ~90:1 (compared to testosterone at 1:1 reference)
• •Bioavailability: Oral — RAD-140 is active via oral administration (research-grade oral solutions are common)
• •Half-life: ~60 hours (approximately 2.5 days), enabling once-daily research dosing
• •Androgen receptor affinity: Ki ~7 nM — comparable to testosterone (~2 nM), substantially higher than most other SARMs

Pharmacokinetics

RAD-140's extended half-life of approximately 60 hours (confirmed in primate pharmacokinetic studies) distinguishes it from shorter-acting SARMs like Ostarine (~24-hour half-life). This extended half-life has two key research implications:

1. Once-daily dosing maintains near-steady-state plasma concentrations

2. Accumulation: During the first week of research, plasma RAD-140 concentrations will gradually increase until true steady state (~5 half-lives ≈ 12–13 days) is reached

Bioavailability studies in primates demonstrate approximately 69% oral bioavailability, making oral research solutions a reliable administration route.

Dosage Protocols in Research Models

Standard Research Dosing

Important note on human clinical data: As of 2026, Phase I clinical trials of RAD-140 have been conducted for breast cancer indications. Published Phase I data (Bardia et al.) demonstrated activity in ER+/AR+ metastatic breast cancer, providing the first human pharmacokinetic data for the compound.

Cycling Framework

Research protocols involving RAD-140 typically follow defined on/off periods:

• •Short research cycle: 8 weeks on, 6–8 weeks off
• •Standard research cycle: 10–12 weeks on, 8–10 weeks off
• •Post-cycle monitoring period: Minimum 4 weeks to assess HPG axis recovery (testosterone, LH, FSH normalization)

Combination Research Protocols

RAD-140 is commonly studied in combination with:

• •MK-677 (Ibutamoren): For combined AR + GH/IGF-1 axis research
• •Cardarine (GW501516): For combined anabolic + PPARδ agonism research on metabolic parameters
• •Standard anabolic agents: For comparative anabolic-to-androgenic ratio studies

Clinical Trial Data: Breast Cancer Research

RAD-140's most clinically advanced application is in ER+/AR+ breast cancer. Androgen receptor is expressed in approximately 70–90% of ER+ breast cancers, and androgen signaling can suppress estrogen-driven proliferation in these tumor subtypes. The rationale for a high-anabolic, tissue-selective AR agonist in this context is to leverage AR's anti-proliferative role in breast tissue selectively.

Phase I data published from the RADIANT trial demonstrated:

• •RAD-140 was generally well-tolerated at doses up to 150 mg/day
• •Objective responses were observed in heavily pre-treated ER+/AR+ metastatic breast cancer patients
• •Pharmacokinetic profile confirmed extended half-life (~60 hours) in human subjects

Monitoring Parameters for Research Protocols

Responsible RAD-140 research protocols include:

• •Testosterone and LH/FSH: SARMs suppress the hypothalamic-pituitary-gonadal (HPG) axis to varying degrees; HPG suppression should be quantified at baseline, mid-cycle, and end-of-cycle
• •Liver function tests (AST, ALT): Hepatotoxicity has been reported in case reports; liver enzymes should be monitored in research contexts
• •Lipid panel: SARMs can alter HDL/LDL ratios; baseline and follow-up lipid profiles are standard
• •Hematocrit/hemoglobin: Androgen receptor stimulation can increase erythropoiesis

Comparative Analysis: RAD-140 vs. Other SARMs

RAD-140's combination of high anabolic:androgenic ratio, extended half-life, and clinical trial validation makes it one of the most well-characterized SARMs available for research purposes.

Key Published Literature

1. Jayaraman A, et al. "Selective androgen receptor modulator RAD140 is neuroprotective in cultured neurons and rats." Endocrinology, 2014. — Demonstrates neuroprotective properties via AR activation, suggesting research applications beyond anabolism.

2. Bardia A, et al. "Phase I study of RAD140, an oral selective androgen receptor modulator (SARM), in ER+/AR+ metastatic breast cancer." Journal of Clinical Oncology, 2021. — First human PK/PD data for RAD-140.

3. Miller CP, et al. "Design, synthesis, and preclinical characterization of the selective androgen receptor modulator (SARM) RAD140." ACS Medicinal Chemistry Letters, 2011. — Original discovery paper; foundational pharmacology data.

Safety and Research Considerations

RAD-140 research should account for:

• •HPG axis suppression: Even tissue-selective SARMs partially suppress endogenous testosterone production via hypothalamic GnRH reduction. Research protocols must include appropriate washout periods
• •Hepatotoxicity risk: Case reports of elevated liver enzymes with SARM use exist; liver function monitoring is mandatory in any responsible research protocol
• •Cardiovascular parameters: HDL reduction has been observed in some SARM studies
• •No FDA approval pathway: Unlike testosterone therapies, SARMs do not have an approved therapeutic indication for most uses; all research is outside of approved medical practice

Conclusion

RAD-140 represents one of the most potent and well-characterized SARMs in the research arsenal. Its extended half-life enabling once-daily dosing, high anabolic-to-androgenic selectivity, and active Phase I clinical trial data for breast cancer make it a compound of significant scientific interest. Research protocols must be designed with appropriate monitoring frameworks, defined cycle durations, and post-cycle recovery assessment to generate valid and reproducible data.

For research purposes only. Not for human use.

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This article is for educational and research purposes only. Peptides.SO does not endorse or encourage the use of research compounds for human consumption. Consult a licensed healthcare professional for any medical concerns.