Comparison

Ipamorelin vs PEG-MGF

Function

While Ipamorelin is investigated for producing moderate, physiologic-like GH pulses useful for studying anabolic, body-composition, and recovery effects with a relatively clean endocrine side-effect profile compared with earlier GHRPs16, PEG-MGF is used experimentally to enhance muscle repair and hypertrophy after mechanical overload or injury by stimulating satellite-cell activation and protein synthesis6373138.

Mechanism

While Ipamorelin works as a third-generation pentapeptide growth hormone secretagogue that selectively agonizes the ghrelin (GHSR-1a) receptor to trigger controlled, GH-specific pituitary release with minimal effects on cortisol or prolactin16269596, PEG-MGF is a poly(ethylene glycol)-conjugated form of Mechano Growth Factor (IGF-1Ec splice variant) comprising the 24-aa C-terminal E-peptide of IGF-1, designed to extend half-life while activating IGF-1 receptor–mediated anabolic signaling in muscle satellite cells637322138.

Length and Sequence

Ipamorelin is 5 amino acids long, whereas PEG-MGF is longer as it has a length of 24 amino acids. Ipamorelin is made up of a sequence of Aib, Histidine, D-2-Nal, Phenylalanine, Lysine. PEG-MGF is made up of a sequence of Tyrosine, Glutamine, Proline, Proline, Serine, Threonine, Asparagine, Lysine, Asparagine, Threonine, Lysine, Serine, Glutamine, Arginine, Arginine, Lysine, Glycine, Serine, Threonine, Phenylalanine, Glutamic acid, Glutamic acid, Arginine, Lysine.

Receptor

Ipamorelin

Ghrelin/growth hormone secretagogue receptor type 1a (GHSR-1a)169596104

PEG-MGF

Insulin-like growth factor 1 receptor (IGF1R), the canonical receptor for IGF-1 peptides22133134139

Organism or Origin

Ipamorelin

Fully synthetic peptide ghrelin mimetic16

PEG-MGF

Synthetic PEGylated analog of human MGF (IGF-1Ec isoform) 2273138

Gene

Ipamorelin

GHSR

PEG-MGF

IGF1

Sources

16Ipamorelin peptide: A gentle pulse, but is it strong enough?, https://oathpeptides.com/2025/11/05/ipamorelin-peptide-a-gentle-pulse-but-is-it-strong-enough/
96Growth Hormone Secretagogue Receptor - ScienceDirect.com, https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/growth-hormone-secretagogue-receptor
22Mechano growth factor - Wikipedia, https://en.wikipedia.org/wiki/Mechano_growth_factor
63Sourcing, https://exploring-peptides.com/peptide-wikipedia/pegmgf/
73PEG-MGF, https://peptidestandard.com/peg-mgf-research/
133IGF1R - Abcam, https://www.abcam.com/en-us/targets/igf1r/24611
134Insulin-like growth factor 1 receptor - Wikipedia, https://en.wikipedia.org/wiki/Insulin-like_growth_factor_1_receptor
138A Splice Variant of IGF-1 within the Growth Plate | PLOS One, https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0076133
139IGF1 receptor signaling pathways, https://pubmed.ncbi.nlm.nih.gov/29535161/