← Shelf·Selective GHSR agonist (GHRP)·XV.
Ipamorelin.
A synthetic pentapeptide — Aib-His-D-2-Nal-D-Phe-Lys-NH₂ — that acts as a selective agonist of the growth-hormone secretagogue receptor (GHSR / ghrelin receptor). Discovered and characterized by Kirsten Raun and colleagues at Novo Nordisk in the mid-1990s.
Ghrelin is the endogenous ligand for the GHSR — a hormone your stomach and hypothalamus produce that engages that receptor. Ipamorelin is a synthetic selective agonist designed to activate the same receptor without the appetite and cortisol effects associated with earlier GHRPs like GHRP-6.
Almost every "growth peptide stack" online pairs Ipamorelin with a GHRH analog (CJC-1295 or Sermorelin). The receptor pharmacology and Novo Nordisk's original characterization work are published. The specific stack-and-dose protocols circulating in the peptide-user community are largely tradition, not trial-based.
Straight talk
Straight talk: Ipamorelin's receptor pharmacology is real and characterized. Never developed as a clinical drug — Novo Nordisk deprioritized the program. Human clinical trial data is limited; nearly all applied dosing patterns in circulation come from clinics, forums, and anecdote, not from published trials. It is a research chemical with a solid mechanism story and a thin clinical story.
What the research studies
The literature, not a summary of it.
The founding work is Raun, Hansen, and the Novo Nordisk GHSR agonist program. GHSR receptor biology traces to Howard, Feighner, and the Merck cloning-era literature. Journals: Eur J Endocrinol, J Endocrinol, Growth Horm IGF Res. Read the research yourself:
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