Ipamorelin (Aib-His-D-2-Nal-D-Phe-Lys-NH₂) is a synthetic pentapeptide growth hormone (GH) secretagogue developed at Novo Nordisk in the 1990s. It acts as a selective agonist at the growth hormone secretagogue receptor (GHS-R1a / ghrelin receptor), stimulating GH release from pituitary somatotroph cells via a mechanism distinct from endogenous GHRH.

Raun, Hansen, and colleagues at Novo Nordisk published the landmark characterization of Ipamorelin in 1998, demonstrating selective and potent GH-releasing activity in rats and swine without concurrent increases in cortisol, prolactin, or ACTH — a selectivity profile that differentiated it from earlier secretagogues GHRP-2 and GHRP-6. Subsequent preclinical models have investigated Ipamorelin’s effects on growth velocity, longitudinal bone growth, body composition parameters, and IGF-1 axis modulation in GH-deficient rodent states. The compound has also been examined for its absence of desensitization at repeated-dosing time points in several animal species. All findings referenced here derive from preclinical models and have not been validated in controlled human clinical trials.

Ipamorelin research appears in European Journal of Endocrinology, Growth Hormone & IGF Research, and Endocrinology. It is not approved by the U.S. Food and Drug Administration for any diagnostic, therapeutic, or preventive application. It is classified as a research compound only.