Ipamorelin
A selective GH secretagogue that mimics ghrelin at GHS-R.
Identity
- Class
- Synthetic pentapeptide GH secretagogue (GHRP)
- Source
- Synthetic ghrelin-receptor agonist
- Receptor
- Growth hormone secretagogue receptor (GHS-R1a)
Key properties
Molecular weight
~711.9 Da
Approximate values for the native hormone. Engineered analogs are often deliberately larger and far longer-acting.
Mechanism
Ipamorelin is a synthetic pentapeptide that activates the ghrelin receptor GHS-R1a to trigger GH release, working through the secretagogue pathway rather than the GHRH receptor. It was engineered for selectivity — releasing GH with little effect on cortisol or prolactin, unlike earlier GHRPs — which is why it is often paired with a GHRH analog for additive, still-pulsatile GH output.
Reference notes
- Introduced as 'the first selective growth hormone secretagogue' — its calling card is minimal cortisol and prolactin release.
- Foundational efficacy data are largely preclinical (rodent); it was trialed in humans for postoperative ileus, but development was discontinued.
- Its GHS-R pathway is synergistic with GHRH analogs because the two act on different receptors.
Selected literature
Curated peer-reviewed reviews, sourced from PubMed. Selected for relevance, not exhaustive — open any entry on PubMed for the full record and its primary citations.
- 1.Ipamorelin, the first selective growth hormone secretagogue · European journal of endocrinology, 1998 · PMID 9849822
- 2.Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats · Growth hormone & IGF research, 1999 · PMID 10373343
- 3.Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance · Sports medicine (Auckland, N.Z.), 2026 · PMID 41966639