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FDA Category 2 · restricted from compounding

This compound is on the FDA’s interim Section 503A Category 2 bulks list and cannot be legally compounded by US pharmacies. An HHS announcement in February 2026 signaled intent to restore several peptides to Category 1, but no Federal Register action has been published. Check the FDA PCAC schedule for updates.

Read the full regulatory context
PreclinicalMuscleSubQTraining daysPartial data

PEG-MGF

Pegylated Mechano Growth Factor · MGF C-peptide

PEGylated 24-aa IGF-1Ec E-peptide that activates muscle satellite cells via a non-IGF-1R pathway. Grey-market use with no registered trials.

§ 01   Overview

Overview

PEGylated 24-aa IGF-1Ec E-peptide that activates muscle satellite cells via a non-IGF-1R pathway. Grey-market use with no registered trials.

Goldspink lab characterization. No registered clinical trials.

§ 02   Mechanism

Mechanism of action

Mechano Growth Factor (MGF) is the C-terminal E-peptide of the IGF-1Ec splice variant, produced by muscle after mechanical overload. It activates satellite cell proliferation through a receptor distinct from IGF-1R. PEGylation extends half-life for exogenous use.

  • 01Satellite cell proliferation after mechanical overload
  • 02PEGylation improves half-life vs. native MGF

§ 03   Dosing

Dosing protocol

Standard Protocol

Dose Range
200 – 400 mcg per dose (anecdotal)
Route
SubQ
Timing
Post-workout
Frequency
Training days
Cycle
4–8 weeks

§ 04   Evidence

Evidence & research

Preclinical

Goldspink lab characterization. No registered clinical trials.

FDA Status

Not FDA-approved. WADA prohibited.

§ 06   News

In the news

3 articles from the last 12 months · updates hourly

§ 07   Sourcing

Sourcing & supply

Regulatory status

Restricted from compounding

Placed on the FDA's 503A Category 2 list and cannot be lawfully compounded in the US. No brand pharmacy alternative exists. US buyers encounter only research-use-only (RUO) channels, which the FDA's Intended Use Doctrine treats as unapproved drug sales.

No suppliers in our directory currently stock this compound. For investigational or research-only compounds, legitimate channels may not exist outside clinical trials.

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§ 09   Safety

Safety & side effects

Side effects

  • 01Injection site reactions
  • 02Unknown long-term safety

Contraindications

None specified.

§ 10   Questions

PEG-MGF FAQ

What is PEG-MGF?
PEGylated 24-aa IGF-1Ec E-peptide that activates muscle satellite cells via a non-IGF-1R pathway. Grey-market use with no registered trials. Mechano Growth Factor (MGF) is the C-terminal E-peptide of the IGF-1Ec splice variant, produced by muscle after mechanical overload. It activates satellite cell proliferation through a receptor distinct from IGF-1R. PEGylation extends half-life for exogenous use.
What is PEG-MGF used for?
Reported uses include satellite cell proliferation after mechanical overload and pegylation improves half-life vs. native mgf. Evidence strength is rated Preclinical — see the evidence section for detail.
How is PEG-MGF dosed?
Commonly referenced dosing is 200 – 400 mcg per dose (anecdotal), typically training days, administered SubQ. This is educational reference only; consult a licensed clinician before use.
What are the side effects of PEG-MGF?
Commonly reported side effects include injection site reactions and unknown long-term safety. This list is not exhaustive.
Is PEG-MGF legal?
Placed on the FDA's 503A Category 2 list and cannot be lawfully compounded in the US. No brand pharmacy alternative exists. US buyers encounter only research-use-only (RUO) channels, which the FDA's Intended Use Doctrine treats as unapproved drug sales. FDA status: Not FDA-approved. WADA prohibited..

§ 11   References

Selected references

  1. 01

    Yang & Goldspink FEBS Lett

    PMID: 12471024

  2. 02

    Goldspink JMNI 2007

    PMID: 17062699

This site is for educational and research purposes only. It does not constitute medical advice. Always consult a qualified healthcare provider before using any peptide or supplement.