Search ↗

Comparison

ACE-031 vs YK-11

Both are myostatin inhibitors, so the meaningful differences are in kinetics, evidence and regulatory status.

On published evidence alone, ACE-031 is the better documented of the two (clinical trials). That is a statement about the state of the literature, not a recommendation.

ACE-031 YK-11
Class Myostatin inhibitors Myostatin inhibitors
Evidence Clinical trials In vitro only
Human trials ~4 None published
Half-life ~10-15 days ~6-10 hours
Reported range 500 mcg - 3 mg 5-10 mg
Frequency Every 2-4 weeks (trial protocols) Once daily
Routes Subcutaneous Oral
FDA approved No No
Research use only Yes Yes
Banned in sport Yes Yes
Studied for Muscular dystrophy research (discontinued), Muscle mass research Muscle growth research
Reported side effects Epistaxis, Telangiectasia, Gum bleeding, Headache, Erythema Hepatotoxicity, HPTA suppression, Lipid disruption, Tendon discomfort, Aggression

ACE-031

ACE-031 is a fusion protein joining the extracellular domain of activin receptor type IIB to an antibody Fc region. It acts as a decoy receptor, binding myostatin and related TGF-beta family ligands before they reach the real receptor and so removing the brake myostatin places on muscle growth. Trials in Duchenne muscular dystrophy showed increases in lean mass but were halted after epistaxis and telangiectasia appeared, reflecting the vascular role of the ligands it sequesters.

YK-11

YK-11 is a synthetic steroid derived from dihydrotestosterone with a distinctive gem-dimethyl ester group. It acts as a partial androgen receptor agonist and has been reported in cell culture to increase follistatin expression, which is the basis of the myostatin-inhibitor marketing. Because it is steroidal it carries androgenic liability including hepatotoxicity and HPTA suppression, unlike the true peptides in this class. Human data is absent.

ACE-031 vs YK-11: common questions

What is the difference between ACE-031 and YK-11?

Both are myostatin inhibitors. ACE-031: A soluble activin receptor decoy that increased muscle mass in trials before being discontinued over vascular side effects. YK-11: A steroidal compound marketed as a SARM and a myostatin inhibitor. It is neither a peptide nor, strictly, a SARM.

Which has stronger evidence, ACE-031 or YK-11?

ACE-031 has the stronger evidence base (clinical trials, about 4 human studies) compared with YK-11 (in vitro only).

Are ACE-031 and YK-11 FDA approved?

Neither is FDA approved for any indication.

References

Regulatory and primary sources

  1. WADA Prohibited List ↗ · current year
  2. FDA: Unapproved drugs and "research use only" products ↗ · regulatory status of non-approved products
  3. PubChem compound record (CID 119058028) ↗ · structure, identifiers, synonyms
  4. CAS Registry Number 431579-34-9 ↗ · chemical identity

Published literature

  1. Campbell C, McMillan HJ, Mah JK, et al.. Myostatin inhibitor ACE-031 treatment of ambulatory boys with Duchenne muscular dystrophy: Results of a randomized, placebo-controlled clinical trial.Muscle Nerve 2017.PubMed 27462804 · doi:10.1002/mus.25268
  2. Tsuchida K. Clinical Applications of Ligand Traps Targeting Activin Type II Receptors.Antiinflamm Antiallergy Agents Med Chem 2026.PubMed 41487000 · doi:10.2174/0118715230416604251029062751
  3. Attie KM, Borgstein NG, Yang Y, et al.. A single ascending-dose study of muscle regulator ACE-031 in healthy volunteers.Muscle Nerve 2013.PubMed 23169607 · doi:10.1002/mus.23539
  4. Thevis M, Schänzer W. Detection of SARMs in doping control analysis.Mol Cell Endocrinol 2018.PubMed 28137616 · doi:10.1016/j.mce.2017.01.040
  5. Harding C, Viljanto M, Habershon-Butcher J, et al.. Equine metabolism of the selective androgen receptor modulator YK-11 in urine and plasma following oral administration.Drug Test Anal 2023.PubMed 36519889 · doi:10.1002/dta.3425
  6. Sobolevsky T, Kucherova Y, Ahrens B. Detection of selective androgen receptor modulator YK-11 in a doping control sample.Drug Test Anal 2024.PubMed 37946705 · doi:10.1002/dta.3604
  7. Zhao W, Yin Y, Shi Z, et al.. Discovery and optimization of novel indolecarboxylic acid derivative as potent glucagon-like peptide‑1 receptor agonists.Mol Divers 2026.PubMed 40366550 · doi:10.1007/s11030-025-11213-7
  8. Lee JH, Han JH, Jung EJ, et al.. Development and validation of liquid chromatography-tandem mass spectrometry method for screening six selective androgen receptor modulators in dietary supplements.Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2021.PubMed 33934684 · doi:10.1080/19440049.2021.1906954

Literature retrieved from PubMed on October 16, 2026, favouring human studies and reviews. Numbered markers in the text show which paper supports which statement; uncited entries are background reading.

Read this first This page compares published reference data. It is not medical advice and not a recommendation to use either compound. Several compounds documented on this site are not approved for human use.