ACE-031
What it is
ACE-031, also referred to as ramatercept, is a recombinant dimeric fusion protein that joins the extracellular ligand-binding domain of the human activin receptor type IIB (ActRIIB, also written ACVR2B) to the Fc region of human immunoglobulin G1 (IgG1). It belongs to the class of soluble receptor "ligand trap" biologics rather than to the short linear peptides it is often grouped alongside commercially.
Research context and categorization
ACE-031 is generally grouped under the hormone and metabolic modulator category, and more specifically as a myostatin and activin pathway modulator. It acts as a decoy receptor that binds circulating members of the TGF-beta superfamily, including myostatin and activin, before they can reach their native cell-surface receptors. Because myostatin functions as a negative regulator of skeletal muscle, ACE-031 is commonly discussed in relation to muscle mass and strength regulation.
Historically it was investigated for muscle-wasting conditions and reached clinical study in the context of Duchenne muscular dystrophy and in post-menopausal participants. It should be emphasized that ACE-031 is not FDA-approved and that its developer discontinued the muscular dystrophy program after vascular-related adverse events (such as nosebleeds, small dilated blood vessels, and gum bleeding), later associated with the compound's activity on ligands beyond myostatin, including BMP9, which contributes to blood-vessel homeostasis. Any uses described here are investigational and are not confirmed or approved benefits.
Status
- Regulatory status: Research-only / not FDA-approved. Clinical development was discontinued and no marketing approval exists.
- Sport status: Prohibited under the WADA Prohibited List. It falls under section S4.3, the myostatin inhibitors and activin receptor type II inhibitors within the hormone and metabolic modulators class, and is prohibited at all times, both in-competition and out-of-competition.
Reconstitution notes (general)
For a lyophilized (freeze-dried) protein, concentration equals the milligrams in the vial divided by the millilitres of bacteriostatic water added. For example, a vial reconstituted to 2 mL will be half the concentration of the same vial reconstituted to 1 mL. A reconstitution calculator is available at our reconstitution and blend calculators to convert vial size and diluent volume into a working concentration.
Dilution and handling notes (compound-specific)
ACE-031 is supplied as a white lyophilized solid and is reconstituted before use, so it does behave like a standard freeze-dried powder in that respect. Vials are commonly sold in small sizes such as 1 mg, with larger 10 mg presentations also referenced. A frequently cited example is a 10 mg vial reconstituted with about 2 mL of diluent, which yields roughly 5 mg/mL, while using around 1 mL yields a more concentrated roughly 10 mg/mL solution. Lower water volumes give higher concentration but a smaller, less forgiving measurement window.
Two handling quirks are worth noting. First, because ACE-031 is a large Fc-fusion protein rather than a short peptide, it should be handled gently: direct the diluent stream against the inner vial wall, let it dissolve without vigorous shaking, and avoid foaming, since agitation and shear can drive the protein to aggregate. Expect it to take several minutes rather than dissolving instantly, and a properly reconstituted solution is clear to only very slightly opalescent. Second, some references note that the benzyl alcohol preservative in bacteriostatic water can affect protein stability, so plain sterile water is sometimes preferred as the diluent even though it lacks the antimicrobial preservative that supports a longer in-use window. Confirm the diluent guidance on the specific product's documentation.
Handling and storage
Store reconstituted material refrigerated at 2 to 8 C, kept out of direct light. Wipe the vial stopper with an alcohol swab before drawing, and label the vial with the mix date. A refrigerated in-use window of roughly 4 weeks is commonly cited for reconstituted material. Discard the solution if it becomes cloudy or discolored or if visible particles or floaters appear.
Related reading
Tools and supplies
- Reconstitution & blend calculators
- Bacteriostatic Water 30 ml
- Gansulin Metal Reusable Pen
- 3 ml Glass Cartridges (10-pack)
- Complete Starter Kit
For laboratory and research reference only. Educational content, not medical, dosing, injection, or therapeutic guidance, and not intended for human or animal use. Any research uses described are investigational and not confirmed or approved benefits. Confirm anything involving health with a licensed professional. References linked above.