PEG-MGF
Pegylated mechano growth factor, pegylated IGF-1Ec E-domain peptide
- Common dose
- No tested dose
- Cycle
- No set cycle
- Vial sizes
- Not established
The same 24-amino-acid IGF-1Ec tail as MGF, with a polyethylene glycol chain attached. Pegylation means bonding a chain of polyethylene glycol to a drug so it is bulkier, which slows the kidneys from filtering it out and makes it harder for enzymes to break down, so it is meant to last longer in the body.
Status
- Approval
- Not approved as a drug in the US or EU, and no company has applied.
- US compounding
- Was in FDA Category 2 for pharmacy compounding (503A) from September 29, 2023, for significant safety risks; the nomination was withdrawn, so it is no longer in Category 2 (page content current April 22, 2026). FDA said compounded PEG-MGF may pose significant immunogenicity risk for certain routes and may be hard to characterize, and that it found no human exposure data by any route. Plain MGF is handled separately and sits in Category 3.
- Sport (WADA 2026)
- Banned in sportS2.3 growth factors, which names “Mechano growth factors (MGFs)” outright. Banned at all times, in and out of competition; pegylating the peptide does not change that.
Category 2 is FDA’s list of bulk substances that may present significant safety risks in compounding. The 503A bulks list adds substances that pharmacies may compound with. Advisory committee votes are advice; FDA makes the final decision. Sport status follows the WADA Prohibited List in force since January 1, 2026; athletes should confirm with their anti-doping organization. Checked October 5, 2026. Status of every compound.
How it works
PEG-MGF is the same 24-amino-acid IGF-1Ec tail with a polyethylene glycol chain attached to make it last longer in the body. No study has tested the pegylated peptide in people, animals or cells, so any mechanism is borrowed from plain MGF, whose claimed effect on muscle cells failed replication at two pharmaceutical companies.
AnimalMainly from cell and animal studies; not shown in people.
Not known
Almost everything is unknown: whether a vial is pegylated at all, the chain length, what pegylation does to activity, and what happens in the body. FDA found no human exposure data by any route.
Protocol
No dose has been tested in any published study, in people or animals. Amounts quoted online differ several-fold between sources and rest on user reports.
- Frequency
- Not established
- Route
- Subcutaneous or intramuscular injection (community); no study has given it to a person or an animal
- Cycle
- No established cycle.
No set cycle, shown over 26 weeks
Taking it
Where it goes
No study has given it by any route. Community use is injection under the skin or into muscle, on the reasoning that the longer life makes site-specific injection unnecessary; none of that has been measured.
If you miss a dose
No published guidance.
What to expect
- Any time
Nothing has been measured, in a person or an animal, for the pegylated peptide: no effect, no time course, no dose response, no half-life.
Community - In cell studies of the unpegylated peptide
The 2002 report found increased myoblast growth and delayed differentiation. In 2013, two pharmaceutical companies testing up to 500 ng/mL found no effect on human or mouse muscle cells or primary muscle stem cells.
Animal
Side effects and what to do
Unknown: no published study has given it to a person or an animal
There is no measured side-effect profile at all. Treat anything new as unexplained and stop.
Unknown immune reaction, including to the PEG chain
FDA flagged immunogenicity risk, and anti-PEG antibodies are documented with other pegylated drugs. Stop for hives, swelling or wheeze.
Cell-growth concern carried over from the peptide
The unpegylated peptide stimulated prostate cancer and osteosarcoma cell growth in culture. Any new or growing lump needs medical assessment.
Injection-site redness, swelling or pain
Expected with any injection. A hot, spreading, painful site needs medical care.
Hives with face or throat swelling, trouble breathing, or an injection site that is hot, spreading and painful: stop and get medical help. Have any new or growing lump assessed.
Who should avoid it
No product label covers PEG-MGF, so these come from human studies and from precautions based on how it works. Most important first.
- Anyone with active or past cancer
- PrecautionThe unpegylated peptide made prostate cancer and osteosarcoma cells grow and spread in culture, and the pegylated form has never been tested in any living animal.
- Anyone who has reacted to a pegylated drug
- PrecautionPegylated medicines can raise anti-PEG antibodies, which are linked to hypersensitivity and to loss of effect; nobody has looked for this with PEG-MGF.
- Pregnancy or breastfeeding
- PrecautionNo human safety data exist, and no animal study of this peptide has been published at all.
- Anyone relying on product quality
- PrecautionFDA cited a significant risk of immune reactions and difficulty characterizing the ingredient, and no published analysis of any PEG-MGF product exists.
Interactions
Precaution: follows from how it works or from a related drug, and hasn’t been tested. This isn’t a complete list: a pharmacist or doctor can check a specific medicine or condition.
Tracking and pairing
Worth tracking
- Any new or growing lump
- Injection-site reactions
Often paired with
Usually run on its own.
Human studies
No published human studies of PEG-MGF turned up in our October 2026 review. The evidence note at the top of this page sums up what is known.
Limits of the evidence
Nothing has been published on the pegylated peptide: no human data, no animal data, no measurement of what reaches the blood. FDA said it identified no human exposure data by any route before the nomination was withdrawn. The peptide underneath failed replication in 2013, and the 48–72 hour half-life quoted online has never been measured.
How it’s supplied
Datasheet
- Half-life
- No reliable value has been published.
- Type
- Peptide, 24 amino acids
- Molecular weight
- not fixed: the 24-amino-acid peptide is about 2,868, and the attached polyethylene glycol chain adds an unstated amount, since products do not state the chain length
- Sequence
- YQPPSTNKNTKSQRRKGSTFEERKThe C-terminal E domain of human IGF-1Ec) plus a polyethylene glycol chain of unstated length
- Storage before use
- Freezer (about −20 °C) for long-term storage, kept dry and out of light.
- After mixing or opening
- Fridge (2–8 °C); use within about 4 weeks.
- Molecule: Peptide sequence: the C-terminal 24 residues of human IGF-1 isoform 4 (UniProt P05019-4); weight computed from that sequence and cross-checked with ExPASy ProtParam. No PubChem record, and no published analysis of any pegylated MGF product, so the size and attachment point of the PEG chain are unknown.
- Storage: Community Common practice; no approved label exists for this peptide
Every compound side by side: the half-life chart and the storage chart.
Cautions
- Whether a vial is pegylated at all, and with what length of chain, cannot be checked by the buyer. No published analysis of any PEG-MGF product exists.
- Pegylated drugs can provoke anti-PEG antibodies, which may cause reactions or blunt the drug; nobody has looked for this with PEG-MGF.
- FDA found no human exposure data for PEG-MGF by any route, and flagged immunogenicity risk and difficulty characterizing the ingredient.
- The peptide underneath failed replication: two pharmaceutical companies found no effect on muscle cells at up to 500 ng/mL.
- The “48 to 72 hour half-life” quoted online has never been measured in any published study.
Questions
What is PEG-MGF?
The same 24-amino-acid IGF-1Ec tail as MGF, with a polyethylene glycol chain attached. Pegylation means bonding a chain of polyethylene glycol to a drug so it is bulkier, which slows the kidneys from filtering it out and makes it harder for enzymes to break down, so it is meant to last longer in the body.
How does PEG-MGF work?
PEG-MGF is the same 24-amino-acid IGF-1Ec tail with a polyethylene glycol chain attached to make it last longer in the body. No study has tested the pegylated peptide in people, animals or cells, so any mechanism is borrowed from plain MGF, whose claimed effect on muscle cells failed replication at two pharmaceutical companies. Almost everything is unknown: whether a vial is pegylated at all, the chain length, what pegylation does to activity, and what happens in the body. FDA found no human exposure data by any route.
Is PEG-MGF FDA-approved?
Not approved as a drug in the US or EU, and no company has applied. Was in FDA Category 2 for pharmacy compounding (503A) from September 29, 2023, for significant safety risks; the nomination was withdrawn, so it is no longer in Category 2 (page content current April 22, 2026). FDA said compounded PEG-MGF may pose significant immunogenicity risk for certain routes and may be hard to characterize, and that it found no human exposure data by any route. Plain MGF is handled separately and sits in Category 3.
What is the usual PEG-MGF dose?
From community reports, not established: No dose has been tested in any published study, in people or animals. Amounts quoted online differ several-fold between sources and rest on user reports. These are the amounts sources reference, not recommendations.
Who should avoid PEG-MGF?
No product label covers PEG-MGF, so these come from human studies and from precautions based on how it works. Anyone with active or past cancer: The unpegylated peptide made prostate cancer and osteosarcoma cells grow and spread in culture, and the pegylated form has never been tested in any living animal. Anyone who has reacted to a pegylated drug: Pegylated medicines can raise anti-PEG antibodies, which are linked to hypersensitivity and to loss of effect; nobody has looked for this with PEG-MGF. Pregnancy or breastfeeding: No human safety data exist, and no animal study of this peptide has been published at all. The “Who should avoid it” section lists 1 more group.
How should PEG-MGF be stored?
Before mixing: Freezer (about −20 °C) for long-term storage, kept dry and out of light. After mixing: Fridge (2–8 °C); use within about 4 weeks. This is common practice; no product label covers it.
Is PEG-MGF banned in sport?
Yes. S2.3 growth factors, which names “Mechano growth factors (MGFs)” outright. Banned at all times, in and out of competition; pegylating the peptide does not change that.
Has PEG-MGF been studied in people?
No published human studies turned up in our October 2026 review. The evidence note at the top of this page sums up what is known.
Sources
- FDA, certain bulk drug substances for use in compounding that may present significant safety risks (page content current April 22, 2026)
- Fornaro et al., mechano-growth factor peptide has no apparent effect on myoblasts or primary muscle stem cells (Am J Physiol Endocrinol Metab 2013) PMID 24253050
- Matheny, Nindl and Adamo, minireview: mechano-growth factor, a putative product of IGF-I gene expression (Endocrinology 2010) PMID 20130113
- Thevis et al., mass spectrometric characterization of a biotechnologically produced full-length mechano growth factor relevant for doping controls (Growth Horm IGF Res 2014) PMID 25466910
- WADA 2026 Prohibited List, in force January 1, 2026
For the protocol details
- FDA, certain bulk drug substances for use in compounding that may present significant safety risks: PEG-MGF entry (content current April 22, 2026)
- Esposito, Deventer and Van Eenoo, a C-terminal amidated MGF analogue in black market products (Rapid Commun Mass Spectrom 2012) PMID 22328223
For how it works, who should avoid it and the limits of the evidence
- FDA, certain bulk drug substances for use in compounding that may present significant safety risks, PEG-MGF entry (page content current April 22, 2026)
- Ibrahim et al., polyethylene glycol immunogenicity and hypersensitivity of pegylated products (J Control Release 2022) PMID 36165835
- Garay et al., antibodies against polyethylene glycol in healthy subjects and treated patients (Expert Opin Drug Deliv 2012) PMID 22931049
Doses tagged Community come from public dosing guides and user reports, checked against at least two of them. Those sites aren’t named here because many of them sell peptides or earn commissions on them.