Ipamorelin — Research Dossier
Evidence grading
First described
1998
Raun et al. — Eur J Endocrinol
Human PK/PD studies
2
Limited pharmacokinetic characterisation
Phase 2 trials
1
Postoperative ileus — discontinued
FDA status (2023)
Category 2
Bulk drug substances list — compounding restricted
Ipamorelin is one of the best-characterised selective growth-hormone secretagogues in pharmacology — and a clear case where a clean mechanism sits on top of a thin human evidence base.
Ipamorelin is a synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH₂) derived from growth-hormone-releasing peptide-1, originally developed by Novo Nordisk. It acts as a selective agonist at the ghrelin receptor (GHS-R1a), stimulating pulsatile growth-hormone release.
Its defining feature, reported across studies, is selectivity: it releases GH without meaningfully raising cortisol, prolactin, or ACTH at standard doses — distinguishing it from earlier secretagogues such as GHRP-6.
“Ipamorelin releases GH without meaningfully raising cortisol, prolactin, or ACTH at standard doses — distinguishing it from earlier secretagogues such as GHRP-6.”
— Raun K et al., Eur J Endocrinol 1998
The preclinical evidence
The preclinical foundation is comparatively strong. Raun and colleagues (1998) characterised GH release in rat and swine models, demonstrating selectivity for the GH axis — GH elevation without meaningful co-secretion of cortisol, prolactin, or ACTH at standard doses. Johansen and colleagues (1999) reported longitudinal bone growth in rats.
The ghrelin-receptor mechanism and broader GHS-R1a pharmacology have since been reviewed extensively, including by Ishida and colleagues (JCSM Rapid Communications, 2020), who placed ipamorelin within the historical development of growth-hormone secretagogues.
Human evidence and the clinical programme
Human data is far more limited. Pharmacokinetic and pharmacodynamic work (Gobburu et al., 1999) documented a short half-life with peak GH roughly 30–40 minutes after administration.
The most advanced clinical programme tested ipamorelin for postoperative ileus (sponsored by Helsinn). In patients undergoing bowel resection, it did not shorten time to first meal versus placebo, and the programme was not advanced further. No completed Phase 2 or Phase 3 trial in any other indication has been published.
The selectivity profile is a pharmacological distinction established mainly in preclinical models. It is not a guarantee of individual human response.
Regulatory status
Ipamorelin holds no regulatory approval for any indication in any jurisdiction. In 2023 the US FDA placed it on its Category 2 bulk drug substances list, which restricts its use in compounded preparations.
What this evidence is — and isn’t
These trials studied pharmaceutical-grade Ipamorelin administered under medical supervision in controlled settings. The figures summarised in this dossier describe that published science only.
They are not outcomes associated with research-grade material, and not results attributable to any use of the product sold in this catalogue. Nothing here is an endorsement, recommendation, or instruction for human use.
Nexyra Lab Catalogue
This dossier covers published clinical research on Ipamorelin. Nexyra Lab supplies research-grade Ipamorelin for in vitro laboratory use.
View Ipamorelin in the Nexyra catalogue (research use only) →References
- 1
Raun K, Hansen BS, Johansen NL, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998.
- 2
Gobburu JVS, Agersø H, Jusko WJ, Aarons L. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharm Res. 1999.
- 3
Johansen PB, et al. Ipamorelin and longitudinal bone growth in rats. Not yet confirmed — owner to update. 1999.
- 4
Ishida J, Saitoh M, Doehner W, et al. Growth hormone secretagogues: history, mechanism of action, and clinical development. JCSM Rapid Communications. 2020.
Research & Laboratory Use Only
This dossier is compiled for research planning and educational purposes only. It summarises published scientific literature and does not constitute medical advice, dosing guidance, or a therapeutic claim. All Nexyra Lab products are for research purposes only and are not for human or veterinary use. Nothing in this document should be interpreted as recommending, endorsing, or facilitating the self-administration of any compound.
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