Summary
ACE-031 (ramatercept) is a recombinant decoy receptor that binds myostatin and related ligands so they cannot signal muscle to stop growing. In a 48 person single dose trial it increased lean mass and thigh muscle volume within a month, but a randomized trial in boys with Duchenne muscular dystrophy was stopped early because of nosebleeds, dilated skin vessels, and no significant walking benefit, and development ended in 2011. It was never approved by any regulator, is prohibited by WADA at all times, and is not available through any lawful channel.
What is ACE-031 (ramatercept)?
ACE-031 (ramatercept) is a recombinant fusion protein (extracellular domain of activin receptor type IIB fused to human IgG1 Fc), a myostatin and activin ligand trap. It is also known as Ramatercept, ActRIIB-IgG1, Soluble activin receptor type IIB, ACE 031.
How does it work?
ACE-031 is the extracellular part of activin receptor type IIB (ActRIIB) fused to an antibody Fc fragment. Circulating in the blood, it soaks up myostatin, activin A, GDF-11, and other TGF-beta family ligands before they can bind ActRIIB on muscle cells. Blocking that signal releases the brake on muscle protein synthesis and satellite cell activity. Because ActRIIB ligands also act on blood vessels, bone, and red blood cell production, the same trap produced vascular and hematologic side effects in trials.
| Cluster | Tissue repair and healing |
|---|---|
| Routes | Subcutaneous injection (clinical trials) |
| Conditions studied | Muscle recovery and injury; Muscle wasting and sarcopenia |
| Record | v2, draft, verified Sep 22, 2026 |
What does the evidence say about ACE-031 (ramatercept)?
Two published human trials. A single ascending dose study in 48 healthy postmenopausal women (2013) showed dose dependent increases in total body lean mass (about 3% at the highest dose after 29 days), thigh muscle volume, and bone formation markers, with a drop in fat mass. A randomized placebo controlled trial in ambulatory boys with Duchenne muscular dystrophy (published 2017) was halted after 24 participants because of epistaxis, telangiectasia, and gum bleeding; lean mass rose but the 6 minute walk distance did not improve significantly. No trial has tested it in adults for performance or aging, and the program was discontinued.
| Evidence type | Indexed studies | Participants (human) |
|---|---|---|
| Human randomized trials | 2 | 72 |
| Human observational studies | 0 | n/a |
| Animal studies | 0 | n/a |
| All indexed studies | 2 | 72 |
Human evidence
Attie et al. 2013: 48 healthy postmenopausal women received a single subcutaneous dose of ACE-031 (0.02 to 3 mg/kg) or placebo. At 1 mg/kg and above, total body lean mass increased by roughly 1 kg and thigh muscle volume by about 5% at day 29; fat mass and leptin fell and bone specific alkaline phosphatase rose. Campbell et al. 2017: 24 ambulatory boys with Duchenne muscular dystrophy were randomized to ACE-031 (0.5 or 1 mg/kg every 2 to 4 weeks) or placebo for 12 weeks. Lean mass and bone density increased, 6 minute walk distance showed a nonsignificant trend, and the trial was stopped early for nosebleeds, telangiectasia, and erythema.
Animal evidence
In mice, soluble ActRIIB decoy receptors produce rapid, large increases in skeletal muscle mass (often 30% to 60% within two weeks) across many muscle groups and in models of muscular dystrophy, cancer cachexia, and disuse. Bone mass also increases. These preclinical effects motivated the human program and are summarized in the 2013 human trial report.
Key studies
| Study | Design and population | Outcome | Grade |
|---|---|---|---|
| A single ascending-dose study of muscle regulator ACE-031 in healthy volunteers2013 PMID 23169607 | Randomized, double blind, placebo controlled single ascending dose trialn = 48 Healthy postmenopausal women | Dose dependent increases in total lean mass and thigh muscle volume at day 29 at 1 mg/kg and above; decreased fat mass and leptin; increased bone formation markers | Evidence: Human RCT evidence |
| Myostatin inhibitor ACE-031 treatment of ambulatory boys with Duchenne muscular dystrophy: results of a randomized, placebo-controlled clinical trial2017 PMID 27462804 | Randomized, double blind, placebo controlled trial, 12 weeks, stopped earlyn = 24 Ambulatory boys with Duchenne muscular dystrophy | Increased lean mass and bone mineral density; nonsignificant trend in 6 minute walk distance; trial halted for epistaxis, telangiectasia, and erythema | Evidence: Human RCT evidence |
Conditions studied
| Condition | Grade | Note |
|---|---|---|
| Muscle recovery and injury | Not graded | Peptides marketed for muscle recovery include BPC-157, TB-500, PEG-MGF, IGF-1 LR3, and growth hormone secretagogues. Human evidence for muscle healing is absent for all of them; the supporting data are rodent muscle transection models and mechanistic cell work. Several are WADA prohibited. |
| Muscle wasting and sarcopenia | Evidence: Human RCT evidence | Increased lean mass in healthy women and in boys with Duchenne muscular dystrophy, but the Duchenne trial was halted for nosebleeds and telangiectasia; development ended. |
Is ACE-031 (ramatercept) legal in the United States?
FDA and compounding status
ACE-031 is an investigational biologic that was never submitted for FDA approval; its sponsor ended development in 2011 after the Duchenne trial was halted. It is not on the FDA 503A bulks list, has not been nominated or reviewed by the Pharmacy Compounding Advisory Committee, and as a recombinant fusion protein it is not a candidate for 503A compounding. Products sold under this name are not lawful for human use and their identity cannot be verified.
WADA status
WADA prohibited. Athletes subject to anti-doping testing should treat this as prohibited at all times unless the current prohibited list says otherwise.
Regulatory timeline
- WADA
WADA publishes the 2027 Prohibited List
WADA published the 2027 Prohibited List on September 21, 2026, and it takes effect January 1, 2027. The S2 peptide hormone and growth factor classes are unchanged. BPC-157 is still named under S0, and MOTS-c is still named under S4.4 as an activator of AMP-activated protein kinase. WADA added a note that many peptides without approval for human use fall under S0 or another section, and that a peptide not named on the list may still be prohibited. GLP-1 receptor agonists such as semaglutide and tirzepatide are still not on the list.
- WADA
WADA 2026 Prohibited List takes effect
The 2026 WADA Prohibited List took effect on January 1, 2026 and continues to prohibit the S2 peptide hormone and growth factor classes (GHRH analogs, growth hormone secretagogues, GH fragments, IGF-1 and analogs, MGF, thymosin beta-4 and derivatives, hCG and GnRH-class releasing factors in males), myostatin inhibitors, insulin and the AMPK activator MOTS-c under S4, desmopressin under S5, and BPC-157 under S0. GLP-1 receptor agonists such as semaglutide and tirzepatide are not on the list.
- WADA
WADA 2025 Prohibited List keeps peptide hormones and growth factors banned at all times
The 2025 WADA Prohibited List took effect on January 1, 2025. Section S2 (peptide hormones, growth factors, related substances and mimetics) covers GHRH analogs such as CJC-1295, sermorelin, and tesamorelin, growth hormone secretagogues such as ipamorelin, GHRP-2, GHRP-6, hexarelin, and ibutamoren (MK-677), growth hormone fragments such as AOD-9604, growth factors including IGF-1 and its analogs, MGF, and thymosin beta-4 (TB-500), and chorionic gonadotropin and releasing factors such as gonadorelin and kisspeptin (prohibited in males). Myostatin inhibitors such as ACE-031 fall under S4, insulin under S4 metabolic modulators, desmopressin under S5, and BPC-157 remains an S0 non-approved substance.
Full tracker for ACE-031 (ramatercept) or the category-wide tracker.
What published studies of ACE-031 (ramatercept) used
Ranges below are reported from published studies and labeling only. PeptideAgent does not recommend doses or protocols.
Human trials used single subcutaneous doses of 0.02 to 3 mg/kg in healthy women (Attie 2013) and 0.5 or 1 mg/kg subcutaneously every 2 to 4 weeks for 12 weeks in boys with Duchenne muscular dystrophy (Campbell 2017). Development stopped after these trials, so no dose was ever established for any indication.
Routes reported
| # | Route |
|---|---|
| 1 | Subcutaneous injection (clinical trials) |
What are the side effects and interactions of ACE-031 (ramatercept)?
Side effects
| # | Reported side effect |
|---|---|
| 1 | Nosebleeds (epistaxis), reported in most treated boys in the DMD trial |
| 2 | Telangiectasia (dilated small skin vessels) and gum bleeding |
| 3 | Skin erythema and injection site reactions |
| 4 | Rise in hemoglobin and hematocrit (ActRIIB ligands regulate red cell production) |
| 5 | Decrease in serum FSH observed in the single dose study |
| 6 | Long term safety unknown; program discontinued in 2011 |
Interactions
| # | Interaction |
|---|---|
| 1 | No formal interaction studies exist |
| 2 | Theoretical additive bleeding or vascular risk with anticoagulants and antiplatelet drugs, based on the telangiectasia and epistaxis seen in trials |
| 3 | Theoretical additive erythrocytosis with erythropoiesis stimulating agents or testosterone |
Contraindications
| # | Contraindication |
|---|---|
| 1 | Any use outside a clinical trial; no approved indication exists |
| 2 | Bleeding disorders or hereditary hemorrhagic telangiectasia (based on trial adverse events) |
| 3 | Pregnancy and breastfeeding (no data) |
| 4 | Competitive athletes subject to WADA testing (myostatin inhibitors are prohibited at all times) |
How do people access ACE-031 (ramatercept) legally?
Typical cost: Not available through licensed channels. Research chemical listings for material labeled ACE-031 exist, but the products are unverified and are not lawful for human use.
Verified access options
Step 1
Not legally available: no approved product, no active clinical trials, and not eligible for compounding.
Step 2
Products labeled research use only are not lawful for human use and are not verified for identity or purity.
Access paths are verified against public regulatory records and prescriber licensing. We never list unlicensed vendors.
Compare ACE-031 (ramatercept)
What's actually offered, and what that means for you
Licensed compounding pharmacies, clinics, and telehealth prescribers openly offer many unapproved peptides, and prescribers write prescriptions for them. That does not make ACE-031 (ramatercept) lawful. ACE-031 (ramatercept) is not FDA approved and not on the 503A bulks list, so a pharmacy has no lawful basis to compound it. [3] [5]
Enforcement is uneven. FDA mostly acts through warning letters to compounders and online sellers, Category 2 safety listings, and import alerts that let it detain shipments, rather than stopping every pharmacy. State pharmacy boards oversee pharmacies day to day, and their rules differ. [5] [6] [7] [8] [9]
What changes for you
- No FDA review of the product: FDA does not check a compounded drug's safety, effectiveness, or quality before it is sold. [9]
- Identity, purity, sterility, and dose accuracy can vary from batch to batch. [5]
- Insurance rarely covers it, so you usually pay cash.
- For tested athletes, ACE-031 (ramatercept) is prohibited at all times on the WADA list, whatever the source. [4]
What to check
These checks lower some risks, but they do not make an unlawfully compounded product lawful or safe. Check for:
- A 503A pharmacy licensed in your state (your state board of pharmacy publishes license lookups). [9]
- A real evaluation by a licensed prescriber, not just an online form.
- A certificate of analysis for the specific batch.
Frequently asked questions
Is ACE-031 legal or FDA approved?
No. ACE-031 was an investigational drug studied in a single dose trial in healthy volunteers and one randomized trial in boys with Duchenne muscular dystrophy. Development stopped in 2011 and it was never approved anywhere. It is not eligible for compounding and there is no lawful way to obtain it for human use in the United States. [2] [3]
Does ACE-031 build muscle in humans?
In the only healthy volunteer trial, a single dose of 1 mg/kg or more increased total lean mass by about 1 kg and thigh muscle volume by about 5% within 29 days in 48 postmenopausal women. In boys with Duchenne muscular dystrophy, lean mass also rose over 12 weeks, but walking distance did not improve significantly and the trial was stopped for safety. No study has tested it for strength or performance in healthy adults. [1] [2]
What are the side effects of ACE-031?
The Duchenne trial was halted because of nosebleeds, telangiectasia (dilated skin blood vessels), gum bleeding, and skin redness. Hemoglobin also rose, which is expected because the same receptor pathway regulates red blood cell production. Long term safety was never studied because the program ended. [1] [2]
How was ACE-031 taken in trials?
By subcutaneous injection. Healthy volunteers received a single dose of 0.02 to 3 mg/kg. Boys with Duchenne muscular dystrophy received 0.5 or 1 mg/kg every 2 to 4 weeks for 12 weeks. No maintenance regimen was ever defined because development stopped. [1] [2]
Is ACE-031 banned by WADA?
Yes. Myostatin inhibitors, including agents that reduce or block myostatin signaling such as ActRIIB decoy receptors, are listed under section S4 of the WADA Prohibited List and are prohibited at all times, in and out of competition. [4]
How much does ACE-031 cost?
There is no lawful price because it is not sold through any licensed channel. Listings on research chemical sites cannot be verified as genuine ACE-031, which is a complex recombinant protein that is difficult to manufacture, and those products are not lawful for human use. [3]
ACE-031 vs follistatin: what is the difference?
Both block myostatin, but by different means. ACE-031 is a soluble copy of the myostatin receptor (ActRIIB) fused to an antibody fragment, so it traps myostatin, activins, and GDF-11 in the blood. Follistatin is a natural binding protein for the same ligands. ACE-031 has two published human trials and known vascular side effects; follistatin-344 has no published human trial data. Neither is approved or lawfully available. [1] [2]
Decisions about starting, stopping, or combining any treatment belong with a licensed clinician who knows your history.
From the blog
- Peptides for muscle growth, ranked by human evidence
MK-677, sermorelin, tesamorelin, CJC-1295, IGF-1 LR3, and more ranked by human evidence. None is approved for muscle growth, and all ten are banned in tested sport.
Sources
Numbered citations above point to these primary sources. PubMed entries link to the indexed abstract.
- [1]Attie KM et al. A single ascending-dose study of muscle regulator ACE-031 in healthy volunteers. Muscle Nerve 2013PubMed 23169607, 2013
- [2]Campbell C et al. Myostatin inhibitor ACE-031 treatment of ambulatory boys with Duchenne muscular dystrophy: results of a randomized, placebo-controlled clinical trial. Muscle Nerve 2017PubMed 27462804, 2017
- [3]FDA: Bulk drug substances used in compounding under section 503A of the FD&C Act (links to the Category 1, 2, and 3 lists and the bulks list)FDA, 2026
- [4]WADA Prohibited List, section S4 (hormone and metabolic modulators, including myostatin inhibitors)WADA, 2026
- [5]FDA: Certain bulk drug substances for use in compounding may present significant safety risks (Category 2)FDA
- [6]FDA: Compounding inspections, recalls, and other actions (warning letters to compounders)FDA
- [7]FDA warning letters database: July 30, 2019 letter to a 503A pharmacy that compounded BPC-157 acetate outside section 503AFDA, 2019
- [8]FDA Import Alert 66-41: Detention without physical examination of unapproved new drugs promoted in the U.S. (includes peptide entries)FDA
- [9]FDA: Compounding and the FDA, questions and answersFDA
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Free to cite and quote with a link. Data is licensed CC BY 4.0 with attribution to PeptideAgent.
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PeptideAgent. (2026, September 22). ACE-031 (ramatercept): evidence, legality, and access. https://peptideagent.ai/peptides/ace-031- HTML link
<a href="https://peptideagent.ai/peptides/ace-031">ACE-031 (ramatercept): evidence, legality, and access</a>, PeptideAgent, updated September 22, 2026.