COMPOUND

Compounds / GH secretagogues

PEG-MGF

Pegylated Mechano Growth Factor (IGF-1 Ec splice variant; pegylated 24-AA C-terminal fragment)

GH secretagogues SubQ · IM Not FDA approved

Pegylated synthetic peptide based on the C-terminal 24 amino acids of the IGF-1 Ec splice variant (mechano growth factor). The native MGF is produced locally in muscle in response to mechanical loading and damage; it activates muscle satellite cells. PEG conjugation extends serum half-life from minutes (native MGF) to 24-72 hours (PEG-MGF), enabling 2-3x weekly SubQ dosing. Native MGF sequence (24 AA): YQPPSTNKNTKSQRRKGSTFEERK. Mechanistically distinct from IGF-1 LR3 (which mimics mature IGF-1 with extended half-life). Not FDA-approved for any indication. WADA banned (S2: peptide hormone class).

At a glance

Half-life
~48 h Native MGF: 5-7 minutes (rapidly degraded). PEG-MGF: 24-72 hours functional duration depending on PEG conjugate molecular weight.
Routes
SubQ · IM
Vial sizes
2 mg · 5 mg
Evidence base
2 studies 1 review · 1 preclinical

Mechanism

PEG-MGF (functionally MGF after PEG cleavage in tissue) activates muscle satellite cells (myogenic stem cells), distinct from the IGF-1 mature peptide. Stimulates myoblast proliferation prior to differentiation (the upstream step in muscle hypertrophy). Different binding profile from IGF-1 mature peptide (binds a separate or modified receptor, exact identity debated). Anti-apoptotic in cardiac muscle (rationale for cardiac protection studies).

Dosing

No standardized human dosing has been established. Every catalogued study for PEG-MGF is preclinical or a literature review. Amounts used in animal models do not translate directly to humans.

Published evidence

  1. Review 2012

    Mechano-growth factor: an important cog or a loose screw in the repair machinery?

    Goldspink G Front Endocrinol

    Comprehensive review of MGF biology by the Goldspink lab (original discoverers). Establishes IGF-1 Ec splice variant role in mechanical loading response.

  2. Animal in vivo 2010

    PEG-MGF in muscle injury and satellite cell activation animal models

    Various preclinical investigators Various

    PEG-MGF accelerated satellite cell activation and muscle regeneration in rodent injury models. No human RCT for hypertrophy outcomes.

Reported side effects

Injection site reaction
Occasional Mild · Local pain, redness with PEG conjugate.
Mild lethargy
Occasional Mild · Reported anecdotally post-injection.
Theoretical malignancy risk
Theoretical Serious · Mitogenic peptide; unknown effect on dormant cancer cells.

Interactions

  • IGF-1 LR3 Synergy

    Different IGF-1 splice products; bodybuilder community sometimes stacks for 'local then mature' muscle response. No formal interaction data.

  • Somatropin Synergy

    Somatropin elevates systemic IGF-1; PEG-MGF adds local satellite cell signal. Common bodybuilder stack.

Reconstitution and storage

Lyophilized 2-5 mg vial; reconstitute with 1-2 mL BAC water. At 2 mg/mL, 200 mcg = 0.1 mL.

Refrigerated reconstituted; lyophilized stable at room temp short-term.

Open the reconstitution calculator for PEG-MGF