Overview
Ipamorelin (NNC-26-0161) is a synthetic pentapeptide and highly selective agonist of the growth hormone secretagogue receptor (GHS-R), also known as the ghrelin receptor. Developed by Novo Nordisk in the 1990s, ipamorelin was designed to stimulate growth hormone release with greater selectivity and a cleaner hormonal profile than earlier growth hormone-releasing peptides (GHRPs) such as GHRP-2 and GHRP-6. The defining characteristic of ipamorelin in the research literature is its selectivity: unlike GHRP-2 and GHRP-6, which significantly elevate cortisol, prolactin, and ACTH alongside GH, ipamorelin stimulates GH release with minimal effect on these other hormones. This selectivity has made it a preferred research tool for studying the GH/IGF-1 axis in isolation.
Mechanism of Action
Ipamorelin acts as a selective agonist at the growth hormone secretagogue receptor (GHS-R1a), a G-protein coupled receptor expressed primarily on somatotroph cells in the anterior pituitary gland and on neurons in the hypothalamus. GHS-R1a activation by ipamorelin initiates a Gαq/11-mediated signaling cascade, increasing intracellular inositol trisphosphate (IP3) and diacylglycerol (DAG) levels, which in turn elevate intracellular calcium concentrations and activate protein kinase C (PKC). This signaling cascade triggers the exocytosis of GH-containing secretory granules from somatotroph cells, producing a rapid, pulsatile GH release. Ipamorelin also attenuates the inhibitory effects of som
Research Evidence
- Highly selective GHS-R1a agonist — minimal effect on cortisol, prolactin, or ACTH (Raun et al., 1998)
- Produces rapid, pulsatile GH release comparable to GHRP-6 but with superior hormonal selectivity
- Attenuates somatostatin inhibition of GH secretion, amplifying GH pulse amplitude
- Long-term administration associated with increased bone mineral content in rodent models
- Studied for gastrointestinal motility effects via GHS-R activation in enteric nervous system
Bottom line: Ipamorelin is the most selective growth hormone secretagogue in this catalog, with a well-characterized mechanism and a clean hormonal profile in preclinical models. No completed human clinical trials for ipamorelin exist; all efficacy data are from animal studies. It remains a research compound only.
Research Protocols & Dosage
Evidence-based research protocols, administration routes, and dosage considerations for Ipamorelin are detailed in the full compound profile. See also: Dosage guide for Ipamorelin.
Sourcing & Quality
Ipamorelin is available from Purgo Labs with third-party COA verification and research-grade purity standards. View Ipamorelin at Purgo Labs.