Ipamorelin
A selective ghrelin receptor agonist studied as a growth hormone secretagogue with minimal effects on cortisol or prolactin.
In plain English
Ipamorelin is a synthetic pentapeptide and selective agonist of the ghrelin receptor (GHSR-1a). Unlike older GH secretagogues, it stimulates GH release without meaningfully raising cortisol or prolactin in human trials. Originator development reached Phase 2 for postoperative ileus before being discontinued — not for efficacy, but for commercial reasons. Today ipamorelin is widely used as a research peptide, typically paired with a GHRH analog like CJC-1295. People commonly research ipamorelin for body composition, sleep, and recovery, but rigorous long-term human data are limited.
What it is
Ipamorelin is a synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) and a selective ghrelin receptor agonist.
Mechanism (summary)
Ipamorelin activates the GHSR-1a (ghrelin receptor) on pituitary somatotrophs, releasing growth hormone. Unlike GHRP-6 and GHRP-2, it produces minimal increases in cortisol, prolactin, ACTH, and aldosterone.
Why people research it
- Postoperative ileus (gut motility after surgery)
- Growth hormone secretion
- Body composition
- Recovery and sleep
Human evidence
Phase 2 trials in postoperative ileus showed accelerated GI recovery vs. placebo. Endocrine studies show selective GH release without significant cortisol/prolactin changes. Long-term anti-aging or body-composition RCTs are lacking.
Animal / lab evidence
Robust GH release across species with a clean endocrine selectivity profile.
Key studies
Each summary explains the design, what was found, and what it doesn't prove.
In animals, ipamorelin released growth hormone cleanly, without raising stress hormones the way older drugs did.
After bowel surgery, patients on ipamorelin recovered gut function faster than patients on placebo.
History
Discovered by Helsinn (then by Novo Nordisk) in the 1990s. Phase 2 in postoperative ileus reached completion; commercial development was discontinued.
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