ACE-031
Quick summary
A soluble activin receptor type IIB fusion protein that soaks up myostatin and related ligands. Research focus: myostatin/activin signaling and muscle mass models. SRP's starting dose for this compound is still pending.
Overview
A soluble activin receptor type IIB fusion protein that soaks up myostatin and related ligands. It is studied in muscle-mass research.
Looking for research material? Simple Research Peptides lists ACE-031 (1mg) for laboratory research use.
Mechanism
A decoy receptor (ActRIIB–Fc) that soaks up myostatin, activin and GDF11.
Research areas
- myostatin/activin signaling
- muscle mass models
Storage & reconstitution
Supplied as a freeze-dried (lyophilized) powder in a sealed vial. Unopened vials are generally kept cold and away from light. Labs usually reconstitute it with bacteriostatic or sterile water, letting the liquid run down the vial wall and swirling gently instead of shaking. The solution is then kept refrigerated.
Recommended starting dose (low and slow)
| Starting dose | Pending - to be added by SRP |
|---|---|
| Frequency | Pending - to be added by SRP |
| Reconstitution | Pending - to be added by SRP |
Studied higher doses
Studies have used doses up to the amounts below. Higher doses can be dangerous. Whether a person can reach them safely depends on height, weight, activity level, training and pre-existing conditions. We recommend following the lower starting dose above, and contacting SRP with any questions.
| SRP's highest recommended dose | 1.5 mg twice per week (3 mg total per week) |
|---|
Phase 1 single-dose study (one subcutaneous injection)
Healthy volunteers each received a single injection at one of six dose levels. Results are summarized in our own words.
| Dose (per kg of body weight) | What was seen |
|---|---|
| 0.02 mg/kg | Well tolerated; minimal measurable effect |
| 0.05 mg/kg | Well tolerated; minimal measurable effect |
| 0.1 mg/kg | A trend toward lean mass gain |
| 0.3 mg/kg | A measurable lean mass effect |
| 1.0 mg/kg | A significant lean mass gain |
| 3.0 mg/kg | The largest gain: about 1 kg more lean mass than placebo by day 29 after one injection |
At the top doses fat mass trended down, and a bone-formation marker (bone-specific alkaline phosphatase) rose at the higher doses.
Phase 2 protocol (as designed)
| Item | Protocol |
|---|---|
| Starting dose | 1.0 mg/kg |
| Escalation | Up to 3 mg/kg |
| Route and frequency | Subcutaneous, every 2 weeks |
| Planned length | 12 weeks (24 weeks with the extension) |
| Outcome | Stopped early over safety signals (see Cautions) |
Important: these study doses are per kilogram of body weight. For example, 3 mg/kg works out to about 270 mg for a 200 lb person. They are shown for research context only and are NOT a recommendation. SRP's highest recommended dose stays at 1.5 mg twice per week (3 mg total per week).
Higher doses can be dangerous. Whether a person can reach them safely depends on height, weight, activity level, training and pre-existing conditions. Follow the lower starting dose, or contact SRP with any questions.
Route and timing
Route: Subcutaneous injection after reconstitution is the route most often described in research protocols.
Timing: Pending - to be added by SRP
Cycle length and repeat
Pending - to be added by SRP
Half-life
Approximate, for Bobby's review: Not well characterized in published research.
Side effects
Pending - to be added by SRP
Suggested bloodwork and monitoring
Draft, for Bobby's review: CBC and comprehensive metabolic panel (kidney and liver function, electrolytes) before starting and again after a few weeks; IGF-1, fasting glucose and HbA1c.
Cautions
The Phase 2 trial of ACE-031 was stopped early because of safety signals: nosebleeds, gum bleeding and dilated small blood vessels in the skin (telangiectasia). Watch for any unusual bleeding or new visible blood vessels, and stop and contact SRP if they appear.
Reconstitution calculator
Math aid only. It converts the numbers you enter; it is not dosing advice. For research use only. Prefilled with this page's vial size, reconstitution and low-and-slow starting dose where known; change any value.
Frequently asked questions
What is ACE-031 studied for?
In research it is studied for myostatin/activin signaling and muscle mass models. A decoy receptor (ActRIIB–Fc) that soaks up myostatin, activin and GDF11.
How is ACE-031 given in research?
Subcutaneous injection after reconstitution is the route most often described in research protocols. SRP has not yet published a frequency for this compound.
What amount should a researcher start with?
SRP has not yet published a starting dose for ACE-031. Contact SRP before starting any research protocol, and do not guess.
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Last updated: October 19, 2026