Ipamorelin

Research · Ipamorelin

Overview

Ipamorelin is a synthetic five-residue growth hormone secretagogue (Aib-His-D-2-Nal-D-Phe-Lys-NH2) derived from the GHRP-1 structural series. Developed by Novo Nordisk researchers in the late 1990s, it was described as the first selective growth hormone secretagogue because it releases growth hormone without the accompanying rise in ACTH, cortisol, or prolactin seen with earlier compounds in its class. It is used as a reference ghrelin receptor agonist in endocrine and gastrointestinal motility research.

Mechanism of action

Activates the growth hormone secretagogue receptor type 1a (GHS-R1a), the ghrelin receptor, a G-protein-coupled receptor expressed in anterior pituitary somatotrophs, the hypothalamic arcuate nucleus, and the enteric nervous system. Receptor activation couples primarily to Gq/11, stimulating phospholipase C, inositol trisphosphate generation, and intracellular calcium mobilization that triggers growth hormone exocytosis. Hypothalamic actions include stimulation of GHRH neurons and functional antagonism of somatostatin. Its receptor selectivity profile accounts for the limited effects on the hypothalamic-pituitary-adrenal axis observed in comparative studies. Its small size, metabolic stability, and receptor selectivity have made it a common probe for isolating GHS-R1a-mediated growth hormone responses in vitro and in vivo.

Key research findings

1. 01

   Preclinical swine studies demonstrated growth hormone release comparable in potency to GHRP-6 with no significant increase in ACTH or cortisol, even at exposures well above those required for growth hormone release.

2. 02

   Pharmacokinetic-pharmacodynamic modeling in healthy human volunteers characterized a short half-life and a single episode of growth hormone release following intravenous exposure.

3. 03

   Rodent studies characterized dose-dependent effects on longitudinal bone growth and bone mineral content in young and adult rats.

4. 04

   Rodent models of postoperative ileus characterized effects on gastric emptying and gastrointestinal transit, consistent with enteric ghrelin receptor activity.

Published references

• Ipamorelin, the first selective growth hormone secretagogue

  Raun K et al. — Eur J Endocrinol, 1998 · PMID: 9849822

• Efficacy of ipamorelin, a ghrelin mimetic, on gastric dysmotility in a rodent model of postoperative ileus

  Greenwood-Van Meerveld B et al. — J Exp Pharmacol, 2012 · PMID: 27186127

The information above is derived from published preclinical and clinical research. It is provided for educational purposes only and does not constitute medical advice, diagnosis, or treatment recommendations.