Ipamorelin
A selective pentapeptide growth hormone secretagogue acting at the ghrelin receptor. Notable for releasing GH without the ACTH and cortisol rise seen with earlier GHRPs. Reached phase 2 trials; development discontinued.
| Total citations | 4 |
|---|---|
| Human clinical studies | 2 |
| Animal models | 2 |
| In vitro studies | 0 |
| Reviews / meta-analyses | 0 |
Mechanism of action
Ipamorelin (Aib-His-D-2-Nal-D-Phe-Lys-NH2) acts at the GHRP/ghrelin receptor GHS-R1a rather than the GHRH receptor, confirmed by antagonist profiling in primary rat pituitary cells. It releases growth hormone with potency and efficacy comparable to GHRP-6, with an in vitro EC50 around 1.3 nmol/L.
Its distinguishing property is selectivity. In swine it did not raise ACTH or cortisol even at doses more than 200-fold above the GH ED50, and did not alter FSH, LH, prolactin or TSH — the basis for describing it as the first selective GH secretagogue.
Peer-reviewed literature
Study type is tagged on every entry so animal and in-vitro findings are never mistaken for human clinical evidence.
Ipamorelin, the first selective growth hormone secretagogue
The originating characterisation paper, establishing GHS-R1a activity and the absence of ACTH/cortisol release in swine.
Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats
Chronic administration produced dose-dependent longitudinal bone growth and body weight gain in rats.
Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers
A randomised human volunteer study characterising the PK/PD relationship of GH release following administration.
Prospective, randomized, controlled, proof-of-concept study of the ghrelin mimetic ipamorelin for the management of postoperative ileus
A phase 2 randomised controlled trial in postoperative ileus — the furthest ipamorelin progressed clinically.