Ipamorelin: Selective Ghrelin Agonist for Pulsatile GH Secretion
Ipamorelin is an exceptionally selective growth hormone secretagogue, valued for its ability to stimulate growth hormone release without elevating cortisol, prolactin, or ACTH.
Structural Parameters of Ipamorelin
| Property | Value and Specification | References |
|---|---|---|
| CAS Number | 170851-70-4 (free base) | |
| Molecular Formula | C38H49N9O5 (free base) | |
| Molecular Weight | 711.85 g/mol (free base) | |
| Sequence | Aib-His-D-2-Nal-D-Phe-Lys -NH2 | |
| Selectivity | High selectivity for the growth hormone secretagogue receptor (GHSR) |
Origin, History, and Research Stage
Ipamorelin was discovered by Novo Nordisk A/S in 1998. It was initially evaluated for the treatment of postoperative ileus due to its stimulatory effects on gastric motility. While clinical trials showed a strong safety profile, development was discontinued for commercial reasons. Ipamorelin remains a widely utilized research chemical in muscle preservation, bone density, and endocrine research, and is highly regarded in clinical longevity medicine.
Mechanism of Action and Pharmacokinetics
Ipamorelin is a synthetic pentapeptide that acts as a selective agonist at the growth hormone secretagogue receptor (GHSR/ghrelin receptor) in the brain and pituitary gland. Unlike other GHRPs, Ipamorelin does not stimulate the release of stress hormones like cortisol or ACTH, nor does it elevate prolactin. The inclusion of aminoisobutyric acid (Aib) at its N-terminus provides stability against plasma exopeptidases, extending its half-life to approximately 2 hours. Binding to GHSR triggers intracellular calcium mobilization, stimulating somatotropic cells to release growth hormone in a natural, pulsatile fashion.
Scientific and Clinical Effects
In vivo animal studies show that Ipamorelin promotes longitudinal bone growth and muscle preservation. In clinical research, it increases lean body mass through enhanced nitrogen retention and protein synthesis, stimulates lipid oxidation, improves sleep quality, and supports collagen and skin structure without increasing hunger or altering blood glucose.
