Ipamorelin (NNC 26-0161) is a synthetic pentapeptide growth hormone secretagogue developed at Novo Nordisk and first described by Raun and colleagues in 1998.1 It is a ghrelin / growth hormone secretagogue receptor (GHS-R1a) agonist that, in published studies, stimulated growth hormone (GH) release from the pituitary.1 This page is provided for research-use-only (RUO) reference. Ipamorelin is not an approved drug and the content below is not medical advice or a usage direction. The most clinically advanced study to date — a phase 2 randomized controlled trial in post-surgical patients — did not meet its primary endpoint, so human efficacy data remain limited.3
Sequence & identity
Structure and identifiers per PubChem (CID 9831659; InChIKey NEHWBYHLYZGBNO-BVEPWEIPSA-N).4 Note: ipamorelin contains the non-standard residues Aib (2-aminoisobutyric acid) and D-2-Nal, so it is not a simple linear peptide of standard amino acids.
Mechanisms studied
Researchers describe ipamorelin as an agonist of the ghrelin / growth hormone secretagogue receptor (GHS-R1a). In primary rat pituitary cells, Raun et al. reported a potency (EC₅₀) of 1.3 ± 0.4 nmol/l with maximal efficacy of 85 ± 5%, comparable to GHRP-6.1 The defining observation of that work was selectivity: across the doses tested, researchers reported that ipamorelin did not release ACTH or cortisol at levels significantly different from GHRH alone — even at doses more than 200-fold above the ED₅₀ for GH release — and that it did not affect FSH, LH, prolactin or TSH plasma levels.1 In human-volunteer PK/PD modeling, Gobburu et al. characterized a single episode of GH release peaking near 0.67 hours after dosing.2
Dosing in the research literature
The figures below summarise regimens as reported in published research — they are not recommendations or directions for use.
| Source / model | Regimen reported | Notes |
|---|---|---|
| Gobburu et al. 1999, Pharm Res (PMID 10496658) — human PK/PD study2 | Intravenous ipamorelin administered to healthy human volunteers; researchers reported a terminal half-life of ~2 hours, clearance of 0.078 L/h/kg, and steady-state volume of distribution of 0.22 L/kg, with GH release peaking near 0.67 h. | Reported as studied in a clinical pharmacology trial. Not a usage direction. Exact dose levels are detailed in the primary source; values here describe what researchers administered and observed, not a recommended regimen. |
| Beck et al. 2014, Int J Colorectal Dis (PMID 25331030) — phase 2 RCT3 | In a randomized, double-blind, placebo-controlled trial of 117 bowel-resection patients, 0.03 mg/kg ipamorelin was given by intravenous infusion twice daily on postoperative days 1-7 (or until discharge). | As reported in the study; the primary endpoint (time to tolerate solid food) did not reach statistical significance vs placebo (25.3 h vs 32.6 h; p = 0.15). Provided for research reference only, not as a directive. |
| Raun et al. 1998, Eur J Endocrinol (PMID 9849822) — animal data1 | In anesthetized rats, researchers reported an ED₅₀ of 80 ± 42 nmol/kg with maximal GH response of 1545 ± 250 ng GH/ml. | Preclinical (rat / swine) potency values reported in studies. Not applicable to humans and not a usage direction. |
Effects observed in research
In the foundational preclinical work, researchers observed that ipamorelin stimulated GH release in rat pituitary cells, anesthetized rats and conscious swine, while reporting no significant elevation of ACTH, cortisol, FSH, LH, prolactin or TSH — leading the authors to characterize it as the first GHS-receptor agonist with GH-release selectivity similar to GHRH itself.1 In human volunteers, researchers reported a transient, pulse-like rise in GH consistent with the peptide’s short ~2-hour half-life.2 In the one published phase 2 clinical trial (postoperative ileus), investigators reported that the drug was well tolerated but that the primary clinical endpoint was not met.3 Claims of body-composition, anti-aging or recovery effects in humans are not established by published controlled trials.
Strength of evidence
Grade B — limited human data, strong animal data. The mechanism and selectivity of ipamorelin are well characterized in animal and in-vitro studies.1 Human evidence is limited to early-phase work: a pharmacokinetic/pharmacodynamic study in healthy volunteers2 and a single phase 2 randomized controlled trial that did not reach its primary endpoint, after which development for that indication was discontinued.3 There are no published controlled human trials demonstrating efficacy for muscle growth, fat loss, anti-aging or recovery. Ipamorelin is not an approved medicine in Canada or elsewhere and is offered strictly for research use.
Reconstitution & storage
Reconstitute with bacteriostatic water for laboratory handling. Store lyophilised material frozen and reconstituted material refrigerated. Use Peptigo’s reconstitution calculator and storage cheat sheet for working figures.
References
- Raun K, Hansen BS, Johansen NL, Thøgersen H, Madsen K, Ankersen M, Andersen PH. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552-561. PMID: 9849822. DOI: 10.1530/eje.0.1390552.
- Gobburu JV, Agersø H, Jusko WJ, Ynddal L. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharm Res. 1999;16(9):1412-1416. PMID: 10496658. DOI: 10.1023/a:1018955126402.
- Beck DE, Sweeney WB, McCarter MD; Ipamorelin 201 Study Group. Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients. Int J Colorectal Dis. 2014;29(12):1527-1534. PMID: 25331030. DOI: 10.1007/s00384-014-2030-8.
- National Center for Biotechnology Information. PubChem Compound Summary for CID 9831659, Ipamorelin. Retrieved 2026. https://pubchem.ncbi.nlm.nih.gov/compound/9831659.