Peptides
ACE-031
Also called ActRIIb-Fc
ACE-031 interests lifters because it can block signals that limit muscle growth. Early human research increased muscle-size measures, but this was not a proven strength programme—and a later trial stopped because of blood-vessel-related safety concerns.
Dosage & duration
Early single-dose trial context; not a human performance regimen.
Healthy-volunteer study, highest-dose group
Published example · product-specific- Dose
- 3 mg per kg body weight
- How often
- Single under-skin administration
- How long
- Muscle-size results assessed at day 29
Weight-based amount, not 3 mg total. Do not convert this into an individual dose or repeated cycle.
Sources: 1
Later repeated-dose research raised safety concerns; the single-dose result does not establish safe cycling.
The promise and the setback
Muscle-size signals came before a safety setback
The early signal
-
Size measures
A study in postmenopausal women found higher lean mass and thigh volume.
The later concern
-
Blood-vessel effects
A Duchenne trial stopped over nosebleeds and visibly widened small blood vessels.
Why the myostatin idea is appealing
The promise is lifting a biological brake on muscle growth. ACE-031 catches more than myostatin, which helps explain why its effects cannot be viewed as muscle-only.
What improved in people
A single-dose study in healthy postmenopausal women found higher lean mass and thigh volume in its highest-dose group. It did not establish an effective bodybuilding cycle or lasting athletic performance benefit.
Why development hit a problem
A later trial in boys with Duchenne muscular dystrophy stopped over nosebleeds and small visibly widened blood vessels. The walking-distance result was a nonsignificant trend. Those findings cannot be dismissed just because muscle-size measures moved.
Model details: ACE-031 · relative timing
Compare timing and buildup for this compound. The values are not blood concentrations or a measure of strength.
Shows a relative timing scenario; absolute blood concentrations are not calibrated.
Timing assumptions and sources
Illustrative midpoint of 12.5 days within the reported human 10–15 day range; not a published cohort mean.
One 1 mg input peaks at 1 relative unit after a single dose. Other amounts scale proportionally; overlapping doses add when accumulation is on. Different compounds use separate relative scales.
- Timing half-life used
- 300 hours
- Absorption half-life assumed
- 75 hours
- Reference amount for the relative scale
- 1 mg
- Absorption half-life is assumed to be one quarter of the slower timescale (75 h); it is not a measured absorption parameter.
- A single 1-unit input has a peak of 1 relative unit; scaling and repeated-dose addition are mathematical assumptions. This normalization is independent of the example dose.
- Do not infer a fixed absolute dose from mg/kg without an explicit reference weight.
- Native ActRIIB and the Fc fusion are different molecules.
- The proposed 300 h relative curve uses a range midpoint assumption; it predicts neither blood concentration nor muscle growth.
- Attie et al. 2013 single-dose ACE-031 in healthy volunteers
Forty-eight postmenopausal women received a single 0.02–3 mg/kg SC dose or placebo. Exposure increased linearly; mean terminal half-life was 10–15 days.
- Reichel et al. 2025 analysis of products sold as ACE-031
Products sold as ACE-031 did not contain the authentic Fc fusion; these preparations cannot be assumed to match the clinical molecule.
ace-031-relative-timing-2026-10 · version 1
Common questions
Was the studied dose 3 mg total?
The highlighted group used 3 mg/kg, a body-weight-based research amount. It is not a recommended self-use dose.
Did the trial prove better strength?
The highlighted healthy-volunteer finding concerns lean mass and thigh volume. The later Duchenne walking result was not statistically significant.
Sources Labels, studies and notes behind this guide
Catalog evidence: Human clinical trials. This describes the type of evidence, not a clinical review of every claim.
Summary and fact source checks: 2026-10-07. This records source checking, not medical review of the whole page.
Notes on the quick facts
- Main attraction
- A biological concept with early human muscle-size signals.
- What was measured
- Not proof of better trained-athlete performance.
- Key trade-off
- The later trial was stopped.
- 1. ACE-031 single-dose trial
Healthy postmenopausal volunteers; 3 mg/kg group had higher lean mass and thigh volume at day 29. Not trained-athlete performance.
- 2. ACE-031 Duchenne trial
Trial stopped after second regimen over nosebleeds and telangiectasias; walking-distance trend not statistically significant.
- 3. Attie et al. 2013 single-dose ACE-031 in healthy volunteers
Forty-eight postmenopausal women received a single 0.02–3 mg/kg SC dose or placebo. Exposure increased linearly; mean terminal half-life was 10–15 days.
- 4. Reichel et al. 2025 analysis of products sold as ACE-031
Products sold as ACE-031 did not contain the authentic Fc fusion; these preparations cannot be assumed to match the clinical molecule.
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