No peer-reviewed clinical study reports any dose or route for PEG-MGF in humans . The animal work used the unpegylated E peptide, delivered locally by injection or embedded polymer . As reported on bodybuilding forums catalogued in a 2026 clinical review: 200 to 400 micrograms subcutaneously or intramuscularly . Two or three times weekly, 30 to 60 minutes after training. Convention, not guidance.

PEG-MGF: uses, evidence and status | Inside Your Peptides

compound file

The answer, first. A pegylated 24-amino-acid peptide copied from the C-terminus of an IGF-1 splice variant, IGF-1Ec. Sold for muscle repair since the mid-2000s. The strongest evidence is for satellite cell activation, graded D — animal or mechanism only.

The founding cell work reported that the E-domain peptide increases myoblast proliferation and blocks differentiation, unlike mature IGF-1 ¹¹³.

Two pharmaceutical companies then failed to reproduce any effect at up to 500 nanograms per millilitre ². Every other use — muscle regeneration, cardiac protection after infarction, muscle gain or recovery in people — grade D or E: animal or mechanism data with no controlled human outcome.

What it is used for

Every use graded on its own evidence, not the compound as a whole. 4 outcomes, ranked by what the human record supports.

#outcome · human · animal · gradewhat the best evidence actually shows

01Satellite cell activationno trial · cell culture, contestedgrade DThe founding cell work reported that the E-domain peptide increases myoblast proliferation and blocks differentiation, unlike mature IGF-1 ¹¹³. Two pharmaceutical companies then failed to reproduce any effect at up to 500 nanograms per millilitre ².

02Muscle regenerationno trial · mouse transplant modelgrade DA synthetic MGF E peptide improved myogenic precursor cell transplantation in mice ⁵, and IGF-1Eb messenger RNA rises after muscle damage in rodents ⁴. No animal study has tested the pegylated form that is sold.

03Cardiac protection after infarctionno trial · mouse and ratgrade DGiven at the moment of infarction in mice, the E-domain peptide preserved systolic and diastolic function at two weeks and cut apoptotic nuclei ⁶. Local polymer delivery repeated the result in rats ⁷. Rodents only.

04Muscle gain or recovery in peopleno trial of any design · extrapolatedgrade DNo human study of PEG-MGF has been published, of any design, on any endpoint ¹⁰¹¹. A 2026 clinical review places it in its lowest tier, alongside compounds supported only by preclinical extrapolation and forum narrative ¹⁰.

gradewhat it means

ARegulatory approval, or multiple adequately-powered trials agreeing with each other

BAt least one well-powered human randomised trial, with the direction replicated

CSmall or open-label human trials only

DAnimal or mechanism data only, with no controlled human outcome

EA claim the human trials have already killed

How it works

The proposed mechanism, in three steps. A mechanism is a reason to run a trial, never a substitute for one.

1targetProposed to act through a receptor separate from the IGF-1 receptor, which blocking-antibody experiments implied but nobody has identified.

2signalIn culture the peptide is taken up rapidly and localises to the nucleus rather than triggering IGF-1 receptor signalling.

3effectNo endogenous MGF peptide has ever been isolated from cells, conditioned medium, animal tissue or body fluid.

What it does not do

Claims the current record does not support. Worth knowing before you set expectations.

not supported by the evidence

It is a peptide your muscles already make. No such peptide has been isolated from cells, medium, tissue or body fluid ³. The messenger RNA is real. The circulating peptide is inferred.
Proven to grow satellite cells. Two pharmaceutical companies failed to reproduce it in mouse and human myoblasts and primary muscle stem cells at up to 500 nanograms per millilitre ².
The pegylated version acts like MGF. Pegylation changes pharmacokinetics and tissue exposure, so E-peptide results do not transfer to the conjugate ¹⁰. No study has tested PEG-MGF itself.
Local action only, so it is safe. That comes from forums, not data ¹⁰. MGF E peptide shows autonomous growth-factor activity in human prostate cancer cells ⁸.

How it is used

What published protocols administered, and what the community reports doing. Descriptive on both counts, and never a recommendation.

routeSubcutaneous or intramuscular injection in the community record. No peer-reviewed human study reports any route of administration for PEG-MGF.

formatLyophilised powder in a multi-dose vial, reconstituted with bacteriostatic water. Sold by the milligram.

published dosesNone exist. No peer-reviewed clinical study reports a dosing regimen for PEG-MGF in humans ¹⁰. The animal work used the unpegylated E peptide, delivered locally by injection or embedded polymer ⁵⁶⁷. Those doses do not translate to a vial.

human pharmacokineticsNo human pharmacokinetic data published. Pegylation is promoted as extending stability, and no half-life has been reported for the conjugate ¹⁰.

reported conventionsAs reported on bodybuilding forums catalogued in a 2026 clinical review, 2025 to 2026: 200 to 400 micrograms subcutaneously or intramuscularly ¹⁰. Two or three times weekly, 30 to 60 minutes after training. Cycles of eight to sixteen weeks. That review presents these as behavioural data, not treatment strategies. Convention, not guidance.

This site does not publish protocols to follow. The doses above are what studies administered or what users report, stated as facts about the literature and the market. How protocols are structured, mixing and storage and the reconstitution calculator cover the arithmetic.

What to expect

Where a trial measured it, the trial. Where only the community reports it, that is said out loud.

onsetNo human study has measured onset for PEG-MGF ¹⁰. In the mouse infarct model the E peptide was given at the moment of injury and read out at two weeks ⁶. As reported: nothing that separates from a training block.

most common reportAs reported: soreness and a pump at the injection site. Nothing has been measured in a person, on any endpoint.

adverse effectsNo human safety data exists ¹⁰¹¹. FDA states it has identified no human exposure data on PEG-MGF by any route and cannot say whether it would cause harm ¹¹. The theoretical concern is mitogenic: MGF E peptide drives proliferation in human prostate cancer cells ⁸.

the stop signalNo literature stop signal exists, because no human study exists ¹⁰. Anti-doping treats it as detectable: a full-length MGF preparation was characterised for doping control in 2014 ¹².

Approval and status

What regulators and sport bodies have actually said, separately from what the evidence shows.

approvalNot approved anywhere, for any indication.

FDAPreviously in FDA's compounding category 2, withdrawn by the nominator. FDA states it found no human exposure data on PEG-MGF by any route ¹¹.

sport [WADA]Prohibited at all times under S2.3, mechano growth factors ¹⁴.

sold asresearch chemical

Check the vial

The grade above describes a molecule studied under controlled conditions. It says nothing about the powder in a particular vial.

That gap is the one part of this market a reader can actually close. How to read a certificate of analysis covers the five measures in five minutes, and the 2026 audit grades vendors on the documents they publish against a rubric printed in full.

Questions we get

What is PEG-MGF used for?

It is bought for muscle repair after training and injury. The claim rests on cell work reporting that the E-domain peptide increases myoblast proliferation and blocks differentiation ¹. Rodent studies of muscle and heart repair sit behind it too ⁵⁶⁷.

There is no human study of PEG-MGF, of any design, on any endpoint ¹⁰. Two pharmaceutical companies could not reproduce the founding cell result ².

How is PEG-MGF used?

No peer-reviewed clinical study reports any dose or route for PEG-MGF in humans ¹⁰. The animal work used the unpegylated E peptide, delivered locally by injection or embedded polymer ⁵⁷.

As reported on bodybuilding forums catalogued in a 2026 clinical review: 200 to 400 micrograms subcutaneously or intramuscularly ¹⁰. Two or three times weekly, 30 to 60 minutes after training. Convention, not guidance.

How long does PEG-MGF take to work?

Nobody has measured it in a person. The mouse infarct study dosed at the moment of injury and read out at two weeks ⁶.

Pegylation is promoted as extending exposure, but no half-life has been published for the conjugate ¹⁰. Any timeline you have read for PEG-MGF is a training block described as a drug effect.

Is PEG-MGF an approved drug?

No. PEG-MGF is sold as a research chemical, not as an approved medicine. On our index it is graded animal only on clinical evidence and moderate on community adoption, and those two are rated separately on purpose.

FDA states it has identified no human exposure data on PEG-MGF by any route ¹¹. It cannot say whether the drug would cause harm in humans.

References

Yang SY, Goldspink G. Different roles of the IGF-I Ec peptide [MGF] and mature IGF-I in myoblast proliferation and differentiation. FEBS Lett. 2002;522:156-160. PMID 12095637
Fornaro M, Hinken AC, Needle S, et al. Mechano-growth factor peptide, the COOH terminus of unprocessed insulin-like growth factor 1, has no apparent effect on myoblasts or primary muscle stem cells. Am J Physiol Endocrinol Metab. 2014;306:E150-E156. PMID 24253050
Matheny RW Jr, Nindl BC, Adamo ML. Minireview: mechano-growth factor, a putative product of IGF-I gene expression involved in tissue repair and regeneration. Endocrinology. 2010;151:865-875. PMID 20130113
Hill M, Goldspink G. Expression and splicing of the insulin-like growth factor gene in rodent muscle is associated with muscle satellite cell activation following local tissue damage. J Physiol. 2003;549:409-418. PMID 12692175
Mills P, Dominique JC, Lafreniere JF, et al. A synthetic mechano growth factor E peptide enhances myogenic precursor cell transplantation success. Am J Transplant. 2007;7:2247-2259. PMID 17845560
Mavrommatis E, Shioura KM, Los T, Goldspink PH. The E-domain region of mechano-growth factor inhibits cellular apoptosis and preserves cardiac function during myocardial infarction. Mol Cell Biochem. 2013;381:69-83. PMID 23712705
Pena JR, Pinney JR, Ayala P, et al. Localized delivery of mechano-growth factor E-domain peptide via polymeric microstructures improves cardiac function following myocardial infarction. Biomaterials. 2015;46:26-34. PMID 25678113
Armakolas A, Philippou A, Panteleakou Z, et al. Preferential expression of IGF-1Ec transcript in cancerous tissues of human prostate: evidence for autonomous growth factor activity of MGF E peptide in human prostate cancer cells. Prostate. 2010;70:1233-1242. PMID 20564425
Zablocka B, Goldspink PH, Goldspink G, Gorecki DC. Mechano-growth factor: an important cog or a loose screw in the repair machinery? Front Endocrinol. 2012;3:131. PMID 23125840
Dominikowski A, Rekos Z, Olejarz M, et al. The emerging landscape of performance-enhancing peptides modulating the GH-IGF1 axis. Front Endocrinol. 2026;17:1822475. PMID 42395176
US Food and Drug Administration. Certain bulk drug substances for use in compounding that may present significant safety risks. Content current as of 22 April 2026. fda.gov
Thevis M, Thomas A, Delahaut P, et al. Mass spectrometric characterization of a biotechnologically produced full-length mechano growth factor relevant for doping controls. Growth Horm IGF Res. 2014;24:276-280. PMID 25466910
Ates K, Yang SY, Orrell RW, et al. The IGF-I splice variant MGF increases progenitor cells in ALS, dystrophic and normal muscle. FEBS Lett. 2007;581:2727-2732. PMID 17531227
World Anti-Doping Agency. Prohibited List 2026, International Standard, effective 1 January 2026. wada-ama.org

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