ACE-031
Also known as ACVR2B-Fc, RAP-031
ACE-031 is an engineered fusion protein combining the extracellular domain of the activin receptor type IIB with an antibody Fc fragment, designed to act as a soluble decoy, or trap, that sequesters myostatin and related ligands before they can bind their natural receptor. It was originally developed by Acceleron Pharma and studied in clinical trials for Duchenne muscular dystrophy and other muscle-wasting conditions. Trial results showed measurable increases in lean muscle mass, but the program was discontinued after unwanted vascular side effects emerged. It remains referenced in muscle-research contexts largely because of this human trial history, unlike many peptides in this category.
Reported benefits
- Documented increases in lean muscle mass in early-phase human trials
- Broad-spectrum trapping of multiple myostatin-family ligands
- Extended circulating half-life due to Fc fusion
- Historical clinical data provide more concrete human evidence than most peptides in this category
How it works
By presenting a soluble, high-affinity version of the activin type IIB receptor, ACE-031 intercepts myostatin, GDF-11, and certain activins in circulation before they can bind their membrane-bound receptors on muscle cells. This prevents activation of the Smad2/3 pathway that normally restrains muscle fiber growth, shifting the balance toward hypertrophy. The Fc fusion also extends the molecule's circulating half-life relative to a bare receptor fragment.
Dosing ranges
| Tier | Dose | Frequency |
|---|---|---|
| Low | 0.5 mg | once weekly |
| Moderate | 1 mg | once weekly |
| High | 3 mg | once weekly |
Estimate your dose
Dose estimator
Educational estimate for ACE-031, scaled to body size. Not medical advice.
Read before using
This tool produces a rough, educational estimate by scaling commonly-published research ranges to lean body mass. It is not a prescription, medical advice, or a substitute for a licensed clinician. Most peptides use fixed dosing, not weight-based dosing. Individual needs vary. You are solely responsible for how you use this information.
Mixing & syringe units
Target dose follows the estimate above. Change it there, or edit it directly below.
Reconstitution calculator
How much water to add and how many insulin-syringe units to draw for ACE-031. Educational only.
Draw to this mark
20units
= 0.2 mL for a 1 mg dose
Concentration
5 mg/mL
Doses per vial
10
A U-100 syringe reads 100 units per mL. This is a reconstitution math helper only, not a prescription or dosing advice. Verify every calculation and consult a qualified healthcare provider.
Possible side effects
Stacking notes
Its long half-life and broad ligand-trapping action make combination with other myostatin-pathway agents (e.g., follistatin) largely redundant and potentially additive in risk rather than benefit; not established in any published protocol.
Common protocols
Common questions
What is ACE-031 used for?
ACE-031 is an engineered fusion protein combining the extracellular domain of the activin receptor type IIB with an antibody Fc fragment, designed to act as a soluble decoy, or trap, that sequesters myostatin and related ligands before they can bind their natural receptor. It was originally developed by Acceleron Pharma and studied in clinical trials for Duchenne muscular dystrophy and other muscle-wasting conditions. Trial results showed measurable increases in lean muscle mass, but the program was discontinued after unwanted vascular side effects emerged. It remains referenced in muscle-research contexts largely because of this human trial history, unlike many peptides in this category. Reported benefits include documented increases in lean muscle mass in early-phase human trials, broad-spectrum trapping of multiple myostatin-family ligands, extended circulating half-life due to fc fusion.
What is a typical ACE-031 dose?
Reported ranges run 0.5-3 mg. A low protocol is 0.5 mg once weekly, and a high protocol is 3 mg once weekly. This is reference information, not a dosing recommendation.
What is the half life of ACE-031?
Approximately 20-30 days, reflecting its Fc-fusion structure. That is what sets the dosing frequency, and it is why the timing guidance is morning.
How is ACE-031 administered?
Subcutaneous: into fat, under the skin.
How long is a ACE-031 cycle?
4-6 weeks on, followed by 12+ weeks off. Original trials used single or infrequent dosing given the long half-life; given documented vascular side effects, cautious and infrequent use is emphasized in discussion of this compound.
What are the side effects of ACE-031?
Reported side effects include nosebleeds (epistaxis) reported in trial participants, gum bleeding and skin telangiectasias (dilated blood vessels) observed in trials, discontinued from clinical development due to these vascular safety findings, long-term safety beyond the trial period is not established. Evidence level for this compound is moderate evidence.
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Educational use only, not medical advice. This profile is provided for research and educational purposes. ACE-031 may be a research compound or a prescription medication; nothing here is intended to diagnose, treat, cure, or prevent any disease. Dosing figures reflect commonly-published research ranges, not a prescription. Consult a qualified healthcare provider before making any health decision. Read the full disclaimer →