What Are SARMs? Complete Research Guide 2026 | Selective Androgen Receptor Modulators

What Are SARMs? Complete Research Guide

Selective androgen receptor modulators explained: AR mechanism, how SARMs differ from anabolic steroids, the SARM compound class, clinical development status, and research use framework.

Published April 10, 2026 · Rainbow Peptide Research Team

For Research Use Only (RUO). Not for human consumption or therapeutic use.

What Are SARMs?

SARM stands for Selective Androgen Receptor Modulator. SARMs are a class of synthetic compounds designed to bind the androgen receptor (AR) and activate it in a tissue-selective way — producing anabolic (muscle-building, bone-strengthening) effects in target tissues while minimizing androgenic effects in non-target tissues such as the prostate, scalp, and sebaceous glands.

The "selectivity" concept is the defining feature: traditional androgens (testosterone, DHT) activate AR equally across all tissues, producing a spectrum of both wanted effects (muscle, bone) and unwanted effects (prostate enlargement, virilization, hair loss). SARMs were developed to decouple these effects.

SARMs are currently in various stages of clinical research for conditions including muscle wasting, sarcopenia, cancer cachexia, osteoporosis, and male hypogonadism. None are approved as therapeutic products by any regulatory authority as of 2026. All research chemical supply is For Research Use Only.

Androgen Receptor Mechanism

The androgen receptor (AR) is a ligand-activated transcription factor. When activated:

Androgens or SARMs bind the AR ligand-binding domain
AR undergoes conformational change, translocates to nucleus
AR dimerizes and binds androgen response elements (AREs) in DNA
Recruits tissue-specific coactivator/corepressor complexes
Drives tissue-specific gene expression programs

The tissue selectivity of SARMs arises from step 4: different tissues express different coactivator proteins. When a SARM binds AR, it produces a slightly different receptor conformation vs testosterone — recruiting different coactivators in different tissues, producing different gene expression outcomes.

SARMs vs Anabolic Steroids

Property	Non-Steroidal SARMs	Anabolic Steroids (e.g. Testosterone)
Chemical structure	Non-steroidal small molecule	Steroidal backbone (cyclopentanoperhydrophenanthrene)
AR selectivity	Tissue-selective agonism	Non-selective; activates AR uniformly
5α-reduction (→DHT)	Not applicable	Yes — amplifies androgenic effects in prostate/skin
Aromatization (→E2)	No (most SARMs)	Yes — estrogen effects at high doses
Oral bioavailability	High (most SARMs, 90%+)	Variable; many require injection or 17α-alkylation
Hepatotoxicity	Lower risk (no 17α-AA)	Oral 17α-alkylated steroids: hepatotoxic
Regulatory status (US)	Research chemicals (unscheduled)	Schedule III controlled substances
Approved therapeutic uses	None (investigational)	Yes (TRT, delayed puberty, wasting)

Types of SARMs: The Research Compound Class

The "SARM" market category includes several mechanistic classes:

Non-steroidal AR agonists (true SARMs): RAD-140, LGD-4033, Ostarine (MK-2866), Andarine (S4) — these bind AR directly with tissue selectivity
Ghrelin receptor agonists: MK-677 (Ibutamoren) — stimulates GH release; does not bind AR; grouped with SARMs for commercial/research categorization
Rev-erb agonists: SR9009 (Stenabolic) — activates Rev-erb nuclear receptors; circadian and metabolic biology; grouped with SARMs commercially
PPARδ agonists: Cardarine (GW501516) — activates PPARδ; fatty acid oxidation; grouped with SARMs commercially
Steroidal SARMs: YK-11 — steroidal backbone; partial AR agonism + follistatin induction
SERMs (related category): Enclomiphene — ER modulator for HPTA axis; often co-studied with SARMs

Clinical Development Status (2026)

SARM	Developer	Max Stage	Indication	Status
Ostarine (MK-2866)	GTx / Oncternal	Phase III	Cancer cachexia (NSCLC)	Discontinued (mixed Phase III)
LGD-4033 (VK5211)	Viking Therapeutics	Phase II	Hip fracture rehabilitation	Phase III planned
RAD-140	Radius Health	Phase I	ER+ breast cancer	Discontinued
MK-677	Merck → Ardea	Phase III	GH deficiency, frailty	No approval; development paused
Enclomiphene	Repros → Androvia	Phase III	Secondary hypogonadism	FDA CRL; development ongoing

WADA & Anti-Doping Status

All SARMs are prohibited in sport under WADA's Prohibited List:

S1 — Anabolic Agents: RAD-140, LGD-4033, Ostarine, Andarine, YK-11 and all other AR-binding SARMs
S2 — Peptide Hormones, Growth Factors: MK-677 (GH secretagogue)
S4 — Hormone Modulators: Some SERMs including enclomiphene

Rainbow Peptide does not supply products for athletic performance enhancement. All products are For Research Use Only.

Frequently Asked Questions

What are SARMs?

SARMs (Selective Androgen Receptor Modulators) are a class of synthetic compounds that bind the androgen receptor (AR) with high affinity but produce tissue-selective effects — activating AR-driven gene expression in muscle and bone while producing less androgenic stimulation in the prostate, scalp, and other androgen-sensitive tissues. This selectivity distinguishes them from anabolic steroids, which activate AR uniformly across tissues. SARMs are currently under clinical development for muscle wasting, osteoporosis, and cancer cachexia, but none are approved by any regulatory authority. All current supply is For Research Use Only.

Are SARMs legal to buy for research?

In most jurisdictions — including the US, UK, Canada, and Australia — SARMs are not scheduled controlled substances and are legal to purchase and possess as research chemicals. However, they cannot be sold as dietary supplements, therapeutic products, or for human consumption without regulatory approval (which no SARM currently has). In the US, the SARMs Control Act of 2018 attempted to schedule SARMs as Schedule III controlled substances — it did not pass, but similar legislation may be introduced. In Australia, SARMs are generally unscheduled but cannot be sold for therapeutic use. Researchers should verify the current legal status in their jurisdiction. All Rainbow Peptide SARMs are sold For Research Use Only.

What is the difference between SARMs and anabolic steroids?

The key differences: (1) Structure — anabolic steroids are steroidal compounds (testosterone derivatives with a steroid backbone); most SARMs are non-steroidal small molecules. (2) Conversion — testosterone converts to DHT via 5α-reductase and to estradiol via aromatase; non-steroidal SARMs do not undergo these conversions. (3) Selectivity — SARMs are designed for muscle/bone anabolism with reduced prostate androgenicity; anabolic steroids are less tissue-selective. (4) Potency — anabolic steroids typically have more potent absolute effects due to decades of optimization; SARMs are lower-dose with more selective profiles. (5) Regulatory status — many anabolic steroids are Schedule III controlled substances (US); SARMs are generally unscheduled research chemicals.