ACE-031

ACE-031, also called ramatercept, is a soluble form of activin receptor type IIB fused to human IgG1 Fc. It works as a decoy that binds myostatin and other negative regulators of muscle mass. Two human trials were published, the Duchenne muscular dystrophy study was stopped early over safety findings, and the compound has never been approved anywhere.

Last updated: September 2026

What is ACE-031?

ACE-031 is not a short peptide chain like the compounds most people arrive here for. It is a dimeric fusion protein: the extracellular fragment of the human activin receptor type IIB, joined to the Fc portion of human IgG1. Developed by Acceleron Pharma in Cambridge, Massachusetts, it belongs to a class known as ligand traps. Rather than signalling through a receptor, it soaks up the molecules that would have signalled through it. Unlike most entries in our peptide library, it has genuine published human trial data.

The target is myostatin, the body's own brake on muscle growth, along with related ligands that share the same receptor. Blocking that brake is a long-standing therapeutic idea for muscle wasting conditions, which is why the compound was taken into a trial in boys with Duchenne muscular dystrophy. It is a fundamentally different mechanism from the growth hormone route covered in our HGH peptides guide, where compounds such as ipamorelin and CJC-1295 ask the pituitary to release more of a hormone.

The reason ACE-031 is a research compound and not a medicine is the safety record, not a lack of effect. The Duchenne trial was halted after the second dosing regimen over nosebleeds and telangiectasias, small dilated blood vessels visible at the skin surface. Those effects have nothing to do with muscle, and the published conclusion states that non-muscle-related adverse events contributed to the decision to stop the study. Development did not continue, and the compound remains unapproved.

How It Works

Ligand trap, not a receptor agonist: ACE-031 is a soluble form of activin receptor type IIB. It promotes muscle growth by binding myostatin and other negative regulators of muscle mass before they can reach the real receptor (PMID 23169607).

Disrupting the brake: the fusion protein binds myostatin and related ligands and aims to disrupt their inhibitory effect on muscle development, which is the rationale for testing it in myopathies such as Duchenne muscular dystrophy (PMID 27462804).

Long exposure: in the single ascending dose study, mean area under the curve and mean maximum concentration rose linearly with dose, and the mean half life was 10 to 15 days. That is a biologic timescale, not a daily peptide one (PMID 23169607).

Off-target reach: a 2026 class review states that activin type II receptors are shared receptors for TGF beta family members including activins, GDF11 and myostatin, and that they play critical roles in hematopoiesis, vascular homeostasis and muscle regulation (PMID 41487000). The receptor this compound traps is not muscle specific, and the effects that stopped the Duchenne trial were bleeding and vessel related rather than muscular (PMID 27462804).

Benefits

Statistically significant increase in mean total body lean mass of 3.3 percent by DXA and in thigh muscle volume of 5.1 percent by MRI at day 29 in the 3 mg/kg group (trial result, healthy postmenopausal women, PMID 23169607)
Statistically significant serum biomarker changes that the authors state suggest improved bone and fat metabolism (trial result, healthy postmenopausal women, PMID 23169607)
Trends for increased lean body mass and bone mineral density and for reduced fat mass in boys with Duchenne muscular dystrophy, reported as trends and not as statistically significant results (trial result, PMID 27462804)
A trend for maintenance of 6-minute walk test distance against a decline in the placebo group, explicitly reported as not statistically significant (trial result, PMID 27462804)
Increased lean body mass, increased cross-sectional area of both type I and type II fibres in biceps brachii, and increased absolute and specific force in the extensor digitorum longus (animal study, common marmoset, route not stated in the abstract, PMID 41686840)

Dosing Described in Research and Labels

Phase	Dose	Frequency	Duration
Phase 1: single ascending dose, healthy postmenopausal women	0.02 to 3 mg/kg (trial dose, not a recommendation, PMID 23169607)	One subcutaneous dose. 48 women randomised 3:1 to ACE-031 or placebo, double blind	Single dose. Lean mass and muscle volume measured at day 29
Phase 2: ambulatory boys with Duchenne muscular dystrophy	dose not stated in the abstract (trial dose, not a recommendation, PMID 27462804)	Subcutaneous every 2 to 4 weeks. Randomised, double blind, placebo controlled, ascending dose	Stopped after the second dosing regimen over potential safety concerns of epistaxis and telangiectasias
Any use outside a trial	No established dose	Not established	Not established

These figures summarise what published research and approved labels describe. They are educational, not a recommendation or a personal protocol. Any dose, schedule, or decision to use a compound belongs with a licensed prescriber.

Side Effects

Common

⚠Injection site erythema, listed among the adverse events in the phase 1 single ascending dose study (PMID 23169607)
⚠Epistaxis, meaning nosebleeds. One of the two potential safety concerns that stopped the Duchenne trial after the second dosing regimen (PMID 27462804)
⚠Telangiectasias, small dilated blood vessels visible at the skin surface. The other finding that stopped the Duchenne trial (PMID 27462804)

Rare

•The Duchenne trial abstract states ACE-031 was not associated with serious or severe adverse events. It was stopped for the two non-muscle findings above, not for a severe event (PMID 27462804)
•Beyond these two published trials nothing is characterised. Long-term human safety was never established, because development stopped before any longer study ran

Who Should NOT Use ACE-031

✕Anyone tested under anti-doping rules. ACE-031 is banned under chapter S4.3 of the WADA 2024 List of Prohibited Substances and Methods, and validated laboratory methods to detect it in serum have been published (PMID 40312924)
✕Anyone expecting an approved medicine. ACE-031 has never been pharmaceutically approved in any country, and its clinical development was discontinued (PMID 40312924, PMID 27462804)
✕Anyone treating the published safety signal as theoretical. The recorded reason a paediatric trial was halted was vascular and bleeding related, in supervised patients receiving trial-grade material (PMID 27462804)
✕Pregnancy or breastfeeding. No safety data exists

What to Expect

Day 29, phase 1

The single ascending dose study measured at day 29 and reported a 3.3 percent increase in mean total body lean mass by DXA and a 5.1 percent increase in thigh muscle volume by MRI in the 3 mg/kg group (PMID 23169607). That is one measured timepoint in 48 healthy postmenopausal women after a single dose.

Weekly timepoints

Neither published trial reports weekly timepoints, so there is no week 1, week 2 or week 4 figure to give. Any week by week progression quoted for this compound is (community practice, no trial).

The Duchenne trial window

Dosing was subcutaneous every 2 to 4 weeks and the study was stopped after the second dosing regimen, so the published human experience covers a short window only (PMID 27462804).

Beyond the trials

Development was discontinued and no later human study has been published. Nothing is known about what happens past the windows those two trials covered, including whether any measured gain is retained.

Notes from Ho Chi Minh City

ACE-031 turns up in Ho Chi Minh City gym talk under the myostatin heading, usually next to follistatin, and usually from someone who read a forum thread rather than the trial. It deserves a more careful conversation than most research compounds here for one reason: unlike almost everything else on a Vietnamese research chemical price list, this one actually reached human trials, and the trials are the problem rather than the selling point. A paediatric study in boys with Duchenne muscular dystrophy was halted after the second dosing regimen because of nosebleeds and dilated surface vessels, and the programme did not continue. Two practical local notes. Nobody here carries it: not Long Châu, not Pharmacity, not the international hospital pharmacies in District 7, and no clinic in the city prescribes it, because it is not an approved medicine in any country. And the counterfeit picture is unusually well documented. When a doping control laboratory tested 14 black market products in 2025, none of them turned out to be the Fc fusion protein ACE-031 actually is. If someone has already bought a vial, that finding is the most useful thing on this page. Any decision about an unapproved compound belongs with a licensed physician.

Sourcing in Vietnam

ACE-031 is not stocked at Long Châu, Pharmacity, or any retail pharmacy in Vietnam, and it has never been pharmaceutically approved anywhere, so there is no legitimate supply chain, no branded product and no registered price. This site lists no verified supplier for it and quotes no price. The sourcing risk here is documented rather than theoretical: a 2025 doping control study tested 14 black market ACE-031 products and found only 12 contained an activin receptor IIB immunoreactive protein at all, with mass spectrometry and IdeS protease testing showing that those 12 contained the full-length human activin receptor IIB instead of the Fc fusion protein (PMID 40312924). A certificate of analysis proves less than usual for this compound, because there is no approved reference product to compare a batch against.

FAQ

Q: Is ACE-031 a peptide?

A: Not in the usual sense. It is a dimeric fusion protein of roughly 58 kilodaltons, made of a human activin receptor IIB fragment linked to the Fc part of human IgG1 (PMID 40312924). That is a large biologic, structurally closer to an antibody than to a 15 amino acid chain like BPC-157.

Q: Why was ACE-031 development stopped?

A: The randomised trial in ambulatory boys with Duchenne muscular dystrophy was stopped after the second dosing regimen due to potential safety concerns of epistaxis and telangiectasias. The published conclusion states that non-muscle-related adverse events contributed to the decision to discontinue the study, while noting that myostatin inhibition remains a promising therapeutic approach (PMID 27462804).

Q: What dose was used in the human trials?

A: The phase 1 study gave a single subcutaneous dose in the range 0.02 to 3 mg/kg to 48 healthy postmenopausal women, and the lean mass and thigh volume changes were seen in the 3 mg/kg group (trial dose, not a recommendation, PMID 23169607). The Duchenne trial abstract states subcutaneous dosing every 2 to 4 weeks but gives no milligram figure. Neither is a protocol for anyone outside a supervised trial.

Q: Is what is sold online actually ACE-031?

A: Frequently not. A 2025 doping control analysis tested 14 black market products: only 12 contained any activin receptor IIB immunoreactive protein at all, and mass spectrometry plus protease testing showed those 12 contained the full-length human activin receptor IIB rather than the Fc fusion protein that ACE-031 actually is (PMID 40312924). That is a stronger reason to check a certificate of analysis than anything a seller will tell you.

Q: Does the animal data support the human results?

A: The non-human primate work points the same direction. In common marmosets, ACE-031 increased lean body mass, increased cross-sectional area of both fibre types in biceps brachii, and increased force production in an isolated muscle (animal study, common marmoset, PMID 41686840). Effect on muscle was never the reason development stopped.

Where to Get ACE-031 in Vietnam

See our community-verified supplier list with COA verification and cold-chain shipping to Vietnam.

View Supply Index

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Research & Sources

A single ascending-dose study of muscle regulator ACE-031 in healthy volunteers · Attie KM, Borgstein NG, Yang Y, et al. · Muscle & Nerve (2013) (PMID: 23169607)
Phase 1, double blind, placebo controlled. 48 healthy postmenopausal women, one subcutaneous dose of 0.02 to 3 mg/kg or placebo, 3:1. Lean mass and thigh muscle volume changes reported at day 29 in the 3 mg/kg group.
Myostatin inhibitor ACE-031 treatment of ambulatory boys with Duchenne muscular dystrophy: Results of a randomized, placebo-controlled clinical trial · Campbell C, McMillan HJ, Mah JK, et al. · Muscle & Nerve (2017) (PMID: 27462804)
Randomised, double blind, placebo controlled ascending dose trial. Subcutaneous dosing every 2 to 4 weeks. Stopped after the second dosing regimen over potential safety concerns of epistaxis and telangiectasias. The abstract states no milligram amount.
Gel Electrophoretic Detection of Black Market ACE-031 · Reichel C, Filip T, Gmeiner G, Thevis M · Drug Testing and Analysis (2025) (PMID: 40312924)
Doping control laboratory analysis of 14 black market products. Only 12 contained an activin receptor IIB immunoreactive protein, and those contained the full-length receptor rather than the Fc fusion protein. Also states ACE-031 is banned under WADA chapter S4.3 and has not been pharmaceutically approved.
ACE-031, a soluble activin type IIB receptor, increases muscle mass and strength in the common marmoset (Callithrix jacchus) · Cadena SM, Bogdanovich S, Khurana TS, et al. · PLoS One (2026) (PMID: 41686840)
Non-human primate study over 14 weeks. Reports increased lean body mass, increased fibre cross-sectional area and increased force production. The abstract states no dose and no route.
Clinical Applications of Ligand Traps Targeting Activin Type II Receptors · Tsuchida K · Anti-Inflammatory & Anti-Allergy Agents in Medicinal Chemistry (2026) (PMID: 41487000)
Class-level review of activin type II receptor ligand traps, the family ACE-031 belongs to. Notes that these receptors are shared by activins, GDF11 and myostatin and act in hematopoiesis, vascular homeostasis and muscle regulation. Two traps in the class, luspatercept and sotatercept, have been approved; ACE-031 has not.

Important Disclaimer

Educational content only. Not medical advice. Peptides discussed on this page are not approved by Vietnam’s Ministry of Health (Bộ Y Tế) or the Drug Administration of Vietnam (DAV) for the indications described. Research peptides are not stocked at Long Châu, Pharmacity, or any retail pharmacy in Vietnam. Consult a licensed physician before any use.