ACE-031 is one of the few myostatin blockers that has increased muscle mass in healthy people. In a 2013 study a single dose of 3 mg per kilogram of body weight raised whole-body lean mass by 3.3 percent and thigh muscle volume by 5.1 percent after 29 days. The participants were healthy postmenopausal women, and ACE-031 stayed in their blood for 10 to 15 days. In mice, four weeks of dosing enlarged individual muscles by as much as 46 percent.
What is ACE-031?
ACE-031 is a protein made from the outer part of the activin type IIB receptor, ActRIIB for short, joined to a fragment of a human antibody. In the shop it also appears under the name ACVR2B. The ActRIIB receptor picks up signals in muscle that hold back its growth, and the best known of them is myostatin.
ACE-031 works as a decoy. It circulates in the blood and captures myostatin and related molecules before they reach the real receptor on the muscle cell. The muscle then stops receiving the braking signal. How ACE-031 differs from follistatin, which blocks the same pathway in another way, is explained in the guide on myostatin blockers.
What did the study in healthy people show?
The study was published in 2013 in the journal Muscle and Nerve. It was a double-blind, placebo-controlled trial with 48 healthy postmenopausal women. Each received a single subcutaneous injection of ACE-031 or placebo, in a ratio of three to one. Doses rose from 0.02 to 3 mg per kilogram of body weight.
| What was measured | Result in the 3 mg/kg group, day 29 |
|---|---|
| Whole-body lean mass (DXA) | plus 3.3 percent |
| Thigh muscle volume (MRI) | plus 5.1 percent |
| Half-life of ACE-031 | 10 to 15 days |
| Tolerability | generally good, redness at the injection site |
Both changes in muscle were statistically significant. The blood level of ACE-031 rose in proportion to the dose. Blood markers also suggested a favourable effect on bone and fat turnover.
How long does one ACE-031 injection last?
The half-life of ACE-031 in the human study was 10 to 15 days, so the molecule circulates in the blood for weeks. By comparison, GHRP-6 has a half-life of about 2.5 hours. ACE-031 is a large protein joined to an antibody fragment, while GHRP-6 is a chain of just six amino acids.
That is why the researchers could measure muscle gain 29 days after a single injection. The half-lives of other molecules are compared in the guide on how long a peptide stays in the body.
What did ACE-031 do in animal studies?
The first data come from a 2010 study in mice. Eight-week-old mice received ACE-031 or placebo for 28 days. After that time the treated mice weighed 16 percent more on average than the controls.
| Mouse muscle | Mass gain after 28 days |
|---|---|
| Soleus | 33 percent |
| Plantaris | 44 percent |
| Gastrocnemius | 46 percent |
| Extensor digitorum longus | 26 percent |
Both fibre types grew, slow and fast. The fibre cross-section in the plantaris increased by 57 percent. The researchers stressed that this sets ACE-031 apart from drugs that block only myostatin, which act mainly on fast fibres.
In 2026 a study in marmosets, small monkeys, was described. The animals received ACE-031 for 14 weeks. Their lean mass rose from baseline, which did not happen in the control group. Fibres of both types grew in the biceps, and muscles tested in the laboratory developed more force.
What did the study in boys with Duchenne muscular dystrophy show?
ACE-031 was also tested in boys with Duchenne muscular dystrophy, a disease in which muscles waste away from childhood. They received injections every 2 to 4 weeks. The treated groups showed a trend towards keeping their 6-minute walk distance, while in the placebo group the distance fell.
There were also trends towards higher lean mass and bone density and lower fat mass. The study was stopped after the second dosing schedule because of nosebleeds and dilated small blood vessels, although there were no serious adverse events. The authors considered myostatin blocking a promising direction for treating this disease. ACE-031 is not an approved medicine.
How does ACE-031 compare with follistatin 344?
Both molecules block the same pathway, but their data differ. Follistatin 344 was tested in humans as gene therapy in patients, described in the guide on what studies showed about follistatin 344. ACE-031 was given as a finished protein, in one injection, to healthy people.
| Feature | ACE-031 | Follistatin 344 |
|---|---|---|
| How it works | captures myostatin as a receptor decoy | binds myostatin as a binding protein |
| Studies in humans | healthy women, one protein injection | patients, one gene dose |
| Result in humans | plus 3.3 percent lean mass | longer walk distance in 4 of 6 patients |
| Half-life | 10 to 15 days | the gene worked for a long time, the protein was not studied |
Where to buy ACE-031 and how much does it cost?
The shop has three 10 mg vials of ACE-031:
- ACE-031 10 mg Genheal costs 75 EUR, on backorder,
- ACE-031 10 mg Bio-Peptide costs 80 EUR, in stock,
- ACE-031 10 mg Nouveaux Ltd. costs 105 EUR, in stock.
The cheapest variant in stock is Bio-Peptide, at 8 EUR per milligram. All variants are gathered on the ACE-031 page. How ACE-031 compares with other muscle peptides is covered in the guide on what studies showed about peptides in bodybuilding. The products in the shop are material for laboratory research, not a medicine.
Frequently asked questions
Does ACE-031 increase muscle mass in humans?
Yes, in a 2013 study a single dose of 3 mg/kg increased lean mass by 3.3 percent and thigh muscle volume by 5.1 percent after 29 days in healthy postmenopausal women.
How long does ACE-031 stay in the blood?
The half-life of ACE-031 in the human study was 10 to 15 days, which is why one injection worked for several weeks.
Which muscle fibres does ACE-031 act on?
Both types. In mice the cross-section of slow fibres rose by 22 percent and of fast fibres by 28 percent in the soleus.
How does ACE-031 differ from follistatin 344?
ACE-031 captures myostatin as a receptor decoy and has a single-injection study in healthy people. Follistatin 344 was studied in humans as gene therapy in patients.
How much does ACE-031 cost in the shop?
A 10 mg vial costs 75 EUR from Genheal, 80 EUR from Bio-Peptide and 105 EUR from Nouveaux Ltd.
Sources
- Attie KM, Borgstein NG, Yang Y et al. A single ascending-dose study of muscle regulator ACE-031 in healthy volunteers. Muscle and Nerve, 2013, 47(3): 416-423. https://doi.org/10.1002/mus.23539
- Cadena SM, Tomkinson KN, Monnell TE et al. Administration of a soluble activin type IIB receptor promotes skeletal muscle growth independent of fiber type. Journal of Applied Physiology, 2010, 109(3): 635-642. https://doi.org/10.1152/japplphysiol.00866.2009
- Cadena SM, Bogdanovich S, Khurana TS et al. ACE-031, a soluble activin type IIB receptor, increases muscle mass and strength in the common marmoset (Callithrix jacchus). PLoS One, 2026, 21(2): e0342666. https://doi.org/10.1371/journal.pone.0342666
- 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 and Nerve, 2017, 55(4): 458-464. https://doi.org/10.1002/mus.25268
- Cabrales A, Gil J, Fernández E et al. Pharmacokinetic study of growth hormone-releasing peptide 6 (GHRP-6) in nine male healthy volunteers. European Journal of Pharmaceutical Sciences, 2013, 48(1-2): 40-46. https://doi.org/10.1016/j.ejps.2012.10.006
- Lee SJ, McPherron AC. Regulation of myostatin activity and muscle growth. Proceedings of the National Academy of Sciences, 2001, 98(16): 9306-9311. https://doi.org/10.1073/pnas.151270098