Ipamorelin

Ipamorelin is a synthetic pentapeptide and selective ghrelin receptor (GHS-R1a) agonist developed by Novo Nordisk, studied for its ability to stimulate dose-dependent GH release with minimal co-secretion of cortisol, prolactin, or ACTH compared to earlier GHRP compounds. The research problem with early growth hormone secretagogues was not that they failed to release GH. They released it effectively. The problem was everything that came with it. Cortisol elevation that muddied metabolic data. Prolactin spikes that added variables no researcher asked for. Appetite stimulation that complicated body composition studies. The signal was real but the noise was significant. Ipamorelin was developed by Novo Nordisk specifically to solve the selectivity problem. This pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH₂) targets the ghrelin receptor (GHS-R1a) with high affinity while largely sparing the corticotrophs responsible for ACTH and cortisol co-release. Research consistently shows robust, dose-dependent GH secretion without the hormonal interference that made earlier GHRPs difficult to study in isolation. That selectivity makes Ipamorelin particularly valuable in combination research. When paired with CJC-1295, the two compounds act on complementary pathways, GHRH receptor stimulation and ghrelin receptor activation, producing amplified GH pulse output greater than either achieves alone. This combination has become one of the most studied pairings in GH secretagogue research for that reason. For researchers who need clean GH stimulation without hormonal variables, Ipamorelin is the standard by which selectivity is measured.