Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is Apitegromab?
Plain language first. The technical label stays, but it never stands alone.Overview
The idea is to keep the fat loss and lose less muscle with it. It is not approved for anything, and it is an antibody rather than a peptide.
Apitegromab is an antibody that blocks myostatin, the signal your body uses to limit how much muscle it builds. It is being tested alongside tirzepatide, because a large share of the weight people lose on those drugs is muscle rather than fat.
What it's used for
An experimental antibody given alongside a weight-loss drug, to keep more muscle while still losing fat.
How does Apitegromab work?
What it does in the body, and where.Myostatin is your body's brake on muscle growth. Blocking it lets muscle hold on better. The clever part of this one is which form of myostatin it grabs.
- 01Myostatin tells muscle to stop growingIt is a natural signal that keeps muscle from building without limit. During rapid weight loss, that brake works against you.
- 02It catches myostatin before it is switched onMyostatin is made in an inactive form and activated later. This antibody grabs the inactive version, which is meant to leave related signals alone.
- 03Less muscle is broken down during weight lossIn the trial, people on tirzepatide alone lost about 30% of their weight as muscle. Adding apitegromab brought that down to about 15%.
- 04The trade-off is a little less total weight lostFat loss was slightly higher, but total weight loss was lower, because muscle that would have gone was kept. Whether that is better for health has not been tested.
Where this compound is thought to act.
What else is it used for?
Each use below carries its own evidence level. Approved means regulators have cleared it for that purpose. Investigational means it is in trials. Early research means it is being studied and is not established.
- Keeping muscle during weight loss on tirzepatide, where a trial of 102 people found about half the usual muscle loss preventedInvestigational
- Spinal muscular atrophy, a muscle-wasting disease, which is the main program for this drugInvestigational
The published record
Papers and trials about Apitegromab
17 papers tagged human · 7 not reviews or lab · 4 clinical trial publications
7 registered trials · 1 with posted results
Furthest stage reached: Phase 3, completed, no results posted
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Prohibited at all times, in and out of competition. S4.3 Myostatin- or precursor-neutralizing antibodies (e.g. apitegromab). Non-Specified.RegulatorsCounted from Europe PMC indexing, not read by a person; a human tag can land on reviews, commentary or lab papers; clinical trial publications is the narrower count.
At a glance
Four things to know about Apitegromab
Evidence
Investigational
Category
Muscle building
Common vial
Varies
Half-life
24 to 31 days
How much, and do you cycle it?
The range, and whether you take breaks.10 mg/kg per month (trial dose), monthly. Given for the length of the trial, with no cycling Trial dose
The 24-week trial ran without a break. Nothing is known about what happens to the muscle that was preserved once the drug stops.
24 to 31 daysTrial protocol
Clears in two phases after a single intravenous dose.
Source: Barrett D, et al. Adv Ther 2021;38:3203-3222, DOI 10.1007/s12325-021-01757-z
You can compare this against the whole library to see where it sits.
How is it given?
Dosing context and source notes.Dosed by body weight and given by drip rather than from a vial, so no draw can be shown.
How do you store it?
Before mixing, and after.Dry powder in the freezer or fridge. Once mixed, fridge, and use within about a month.
Unmixed lyophilized Apitegromab keeps for a long time cold. Once you add water the clock starts: most reconstituted vials hold up for roughly 28 to 30 days at fridge temperature. Keep it out of light, and do not freeze it after mixing.
What are the side effects and cautions?
Known cautions and warnings for this compound.This is not something you can buy or mix. It is an antibody given by drip in a clinic during a clinical trial, dosed by body weight at 10 mg for every kilogram. There is no vial size and no syringe draw, so the calculator does not apply here.
Who should avoid it
- Not available outside a clinical trial
- Pregnancy
- No safety record outside the trial setting
Stop and get help
- Signs of an allergic reaction during or after an infusion
- Anything unusual, since the safety record is short
Common effects
- Side effects were about as common as with tirzepatide alone: 76% of people on apitegromab reported at least one, against 71% on placebo
- Serious side effects were rare and even between the groups, one person in each
- Total weight loss was slightly lower, 12.3% against 13.4% over 24 weeks
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is Apitegromab approved?
And where the numbers on this page come from.No. Apitegromab is not approved anywhere and is currently in company-run clinical trials. There is no legal route to obtain it outside a trial.
- Approval statusInvestigational
- RouteInto a vein
- Checked22 September 2026
- DoseFrom published clinical trials. Not approved by a regulator for this dose.
- Vial sizeFrom what vendors typically list; not a recommendation.
- Sources
What has happened recently
Not approved anywhere for anything. The company behind it, Scholar Rock, is developing it mainly for spinal muscular atrophy, a muscle-wasting disease, and the obesity work is a separate early program. Anything sold online under this name is not the trial drug.
What regulators say
From official documentsProhibited at all times, in and out of competition. S4.3 Myostatin- or precursor-neutralizing antibodies (e.g. apitegromab). Non-Specified.
Checked 12 September 2026WADA: The 2026 Prohibited List (in force 1 January 2026)
You can compare this against the whole library, or read how to check a seller.
What else is like Apitegromab?
Others in Muscle building, side by side.If you're weighing Apitegromab, it's worth reading Bimagrumab, Mifomelatide, and Tesamorelin in the same class.
An antibody tested to stop GLP-1 weight loss taking muscle along with fat.
- Dose
- 10 mg/kg per month (trial dose)
- How often
- Monthly
An experimental shot that strips fat while adding muscle.
- Dose
- 10 up to 30 mg/kg per month (trial doses)
- How often
- Monthly
An experimental daily shot that switches off two appetite-suppressing receptors, the reverse of setmelanotide.
- Dose
- 12.5 to 50 mg daily (phase 2 doses)
- How often
- Daily
An approved shot proven to shrink stubborn belly fat.
- Dose
- 1.28 up to 2 mg per day, depending on which product you have
- How often
- Daily
Guides for this compound
- How to Reconstitute a Peptide
Mix peptide powder with bacteriostatic water, step by step.
- How to Read an Insulin Syringe
Read the units, convert to millilitres, and draw the exact dose.
- mcg vs mg: The Peptide Dosing Mistake to Avoid
Your vial says mg and your protocol says mcg. Here is the conversion and how to check it.
- Why Does My Peptide Injection Itch or Welt
Injection-site irritation, a histamine reaction, or a true allergy, and how to tell them apart.
- How to Read a Peptide COA
What the purity number does and does not tell you, and how to spot an edited report.
Sources
- Nature Medicine, Phase 2 EMBRAZE trial of apitegromab with tirzepatide(2026)102 adults over 24 weeks. Apitegromab preserved 1.9 kg more lean mass than placebo (54.9% retention, p=0.001) with similar total weight loss. Side effects 76% vs 71%, one serious event in each arm.
- Scholar Rock, EMBRAZE Phase 2 results announcement(2025)Weight loss was 85% fat and 15% lean with apitegromab, against 70% fat and 30% lean with tirzepatide alone. Total body weight loss 12.3% vs 13.4%.
Beyond these, 25 records are indexed. Browse the records