How long does ACE-031 stay in your system?
ACE-031 has a published half-life of 10 to 15 days. By the standard pharmacology rule of thumb, a drug is about 97% eliminated after roughly five half-lives, which here works out to between 50 and 75 days (7.1 to 10.7 weeks). ACE-031 was never approved, and its development was discontinued on safety grounds.
Source: Attie et al., Muscle Nerve 2013 (PMID 23169607) · Peer-reviewed · measured: subcutaneous · dataset reviewed September 23, 2026
What is the half-life of ACE-031?
ACE-031, also called ramatercept, has a published half-life of 10 to 15 days after subcutaneous injection, from a 2013 single ascending dose study in Muscle & Nerve in 48 healthy postmenopausal women. ACE-031 is not a small peptide. It is a recombinant fusion protein that joins part of the activin receptor type IIB to the Fc region of an antibody, and it works as a decoy that traps myostatin and related signals.
Fusion to an antibody Fc region is an established way of extending a protein's time in circulation, which fits a half-life counted in days. On the five half-life rule, a single dose takes roughly 50 to 75 days to fall by about 97%, a window measured in months rather than hours.
How much ACE-031 is left after each half-life?
Each half-life removes half of whatever is left, so the percentages are pure arithmetic and the same for any compound; only the clock changes. For ACE-031, one half-life is 10 to 15 days. The rows below run that forward for a single amount with nothing added.
| Half-lives elapsed | Time elapsed | Remaining | Cleared |
|---|---|---|---|
| 1 | 10 to 15 days | 50% | 50% |
| 2 | 20 to 30 days (2.9 to 4.3 weeks) | 25% | 75% |
| 3 | 30 to 45 days (4.3 to 6.4 weeks) | 12.5% | 87.5% |
| 4 | 40 to 60 days (5.7 to 8.6 weeks) | 6.25% | 93.75% |
| 5 | 50 to 75 days (7.1 to 10.7 weeks) | 3.13% | 96.88% |
| 6 | 60 to 90 days (8.6 to 12.9 weeks) | 1.56% | 98.44% |
| 7 | 70 to 105 days (10 to 15 weeks) | 0.78% | 99.22% |
Why do the numbers differ between sources?
There is essentially one human pharmacokinetic source for ACE-031, so the variation is mostly within it: 10 to 15 days across the doses and individuals studied. The population was specific, healthy postmenopausal women, and the drug was later tested in Duchenne muscular dystrophy, where pharmacokinetics may differ.
Products sold online under the ACE-031 name are research-grade material, and nothing establishes that they are the fusion protein Acceleron developed. A large biologic is far harder to reproduce faithfully than a short peptide, so the published figure cannot be assumed to apply to them.
What does a half-life not tell you?
A 10 to 15 day half-life means a single exposure lingers for weeks, which matters for interpreting safety. The Duchenne programme was halted over vascular effects, including nosebleeds and small dilated blood vessels, which reflect the drug trapping ligands beyond myostatin. How long such effects persist is not something the half-life can answer.
It also does not describe muscle effects. Releasing the myostatin brake on muscle growth is a tissue process that unfolds over time, separate from the curve of drug concentration in blood.
Can you run the numbers yourself?
The estimator applies the same decay arithmetic to any half-life, starting amount and time you enter. It opens with ACE-031's published value loaded. Type another figure to see how sensitive the result is to it.
Published value: 10 to 15 days (Subcutaneous) · Attie et al., Muscle Nerve 2013 (PMID 23169607) · Compound profile
Show the math
What are the limits of this estimate?
Everything above is a single-compartment approximation: one pool of drug, falling by the same fraction in every interval. Real elimination varies with kidney and liver function, body composition, formulation and route, and a published figure describes only the route and the people it was measured in. Many compounds also show a fast distribution phase before the slower elimination the table describes.
A half-life is not a dosing schedule. Labelled intervals come from clinical trials that measured outcomes and tolerability, and nothing on this page suggests when to take, repeat or stop anything. Whether ACE-031 is out of your system for drug-testing purposes is a different question again. Tests often look for metabolites rather than the parent compound, and the answer depends on the assay, its sensitivity and the sample type, none of which a plasma half-life captures.
FAQ.
Why does ACE-031 last so much longer than most compounds on this site?
Because it is a fusion protein, not a short peptide. It joins the activin receptor type IIB to an antibody Fc region, an established way of extending time in circulation. The published half-life is 10 to 15 days after subcutaneous injection.
Who was ACE-031's half-life measured in?
A single ascending dose study in 48 healthy postmenopausal women, published in 2013. That population may not reflect others, including the people with Duchenne muscular dystrophy in whom the drug was later tested.
Is ACE-031 still in development?
No. Development was discontinued after the Duchenne trial was stopped over safety concerns, and ACE-031 was never approved. Material sold under the name is unapproved research-grade product.
For what the evidence on ACE-031 actually shows, read the ACE-031 profile. For approval and regulatory position, see is ACE-031 legal. The half-life reference lists every sourced value side by side, including the compounds where a number circulates online with no reliable human data behind it.