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A five-residue synthetic secretagogue built to release growth hormone as selectively as possible — and still unapproved after nearly thirty years.
Also known as: NNC 26-0161 · Aib-His-D-2-Nal-D-Phe-Lys-NH2
Part of the Growth hormone & IGF peptides cluster
Overview
Ipamorelin (NNC 26-0161) is a synthetic pentapeptide — Aib-His-D-2-Nal-D-Phe-Lys-NH2 (C38H49N9O5, ≈712 Da) — developed by Novo Nordisk as the first growth hormone secretagogue that released growth hormone without stimulating ACTH or cortisol. It acts at the ghrelin receptor. It has never been approved: phase 2 trials in post-operative ileus were completed without a filing, and it is sold today as an unapproved research peptide and prohibited in sport.
Source & context
Biological / chemical source: Synthetic pentapeptide
Primary research or clinical context: Research compound — never approved. Phase 2 trials for post-operative ileus were completed by Helsinn without an approval; sold unapproved as a research peptide and prohibited in sport.
What ipamorelin is
Ipamorelin is a synthetic five-residue peptide designed to release growth hormone by activating the ghrelin receptor. It came out of a Novo Nordisk chemistry programme that started from the growth hormone-releasing peptide GHRP-1 and searched for compounds lacking its central Ala-Trp dipeptide; the sequence Aib-His-D-2-Nal-D-Phe-Lys-NH2 was selected for high GH-releasing potency and efficacy in vitro and in vivo (Raun et al., European Journal of Endocrinology 1998). Its molecular formula is C38H49N9O5 and its mass about 712 Da — smaller than most peptides on this site, which is one reason it is cheap to synthesise and widespread on the grey market.
Structure: three non-canonical residues in five
Only histidine and lysine in ipamorelin are ordinary amino acids. Position 1 is α-aminoisobutyric acid (Aib), position 3 is D-2-naphthylalanine, position 4 is D-phenylalanine, and the C-terminus is amidated. The D-amino acids and the Aib resist proteolysis and hold the conformation the receptor recognises; the naphthyl side chain supplies the bulky aromatic contact that GHRPs need. Because these residues have no one-letter code, the sequence is shown on this page in three-letter form rather than as a chip strip.
Mechanism and what 'selective' means
Ipamorelin was described in its discovery paper as the first selective growth hormone secretagogue: in the reported pharmacology it released growth hormone from pituitary cells and in animals with potency comparable to GHRP-6, but without the release of ACTH and cortisol that earlier GHRPs caused (Raun et al., 1998). It acts at GHS-R1a, the receptor for ghrelin, the same receptor targeted by GHRP-2, GHRP-6, hexarelin, anamorelin and the oral non-peptide MK-677 (ibutamoren). It does not act at the GHRH receptor, which is why it is so often paired in discussion with the GHRH analogues sermorelin and CJC-1295.
Clinical development
Ipamorelin's only clinical programme was not for growth or body composition. Helsinn Therapeutics ran two phase 2 trials of ipamorelin for the management of post-operative ileus and recovery of gastrointestinal function after surgery (NCT00672074 and NCT01280344, both completed). The evidence pack contains no published efficacy result from either trial and no subsequent phase 3 or marketing application, so the programme is best described as completed without progression. A 2024 ferret study found that ipamorelin, like anamorelin, inhibited cisplatin-induced weight loss (Lu et al., Physiology & Behavior 2024).
| Registration | Sponsor | Question | Status |
|---|---|---|---|
| NCT00672074 | Helsinn Therapeutics | Post-operative ileus | Phase 2, completed |
| NCT01280344 | Helsinn Therapeutics | Recovery of gastrointestinal function | Phase 2, completed |
| NCT07717866 | Axial Therapeutic Research | "Trifecta" research study | Active, not recruiting |
What the human evidence does not contain
There is no published randomised trial of ipamorelin for muscle, fat loss, recovery, sleep or ageing in the pack. A 2026 scoping review of six popular peptides including ipamorelin found that 67% of identified publications were preclinical animal studies and that human clinical studies were limited to a handful of investigations, most lacking robust controls (Tewari et al., American Journal of Sports Medicine 2026). A 2026 gerontology review lists ipamorelin under growth hormone modulation with promising preclinical and limited human data (Mavrych et al., Frontiers in Aging 2026). Claims about body composition in adults rest on the class mechanism, not on ipamorelin trials.
Regulatory status and sport
Ipamorelin has no IUPHAR ligand record and no marketing authorisation anywhere as of September 2026. It is prohibited in sport: recent reviews list it among the growth hormone secretagogues encountered in bodybuilding and self-administration protocols (Coutinho et al., Journal of Sports Medicine and Physical Fitness 2026; Dominikowski et al., Frontiers in Endocrinology 2026). Everything sold under the name is unlicensed material of unverified content.
Ipamorelin vs CJC-1295, sermorelin and MK-677
CJC-1295 and sermorelin act at the GHRH receptor; ipamorelin acts at the ghrelin receptor, so the pairing sold as “CJC/Ipa” combines two receptor pathways — a combination no trial in the pack has tested. MK-677 (ibutamoren) is the non-peptide, oral equivalent of ipamorelin at the same receptor, with a much longer duration. Among the GHRPs, ipamorelin's claim is selectivity: no ACTH or cortisol release in the discovery pharmacology, where GHRP-6 and hexarelin were less selective. This profile is educational; it is not guidance on obtaining or using any product and it is not medical advice.
Structure & chemistry
Molecular identity & reference confidence
Source-supported reference
Reference values are taken from the cited molecular record or curated profile. A database match is not independent laboratory verification; modifications, counter-ions, and formulations can change the measured mass.
- Molecular form
- Pentapeptide Aib-His-D-2-Nal-D-Phe-Lys-NH2, identified in a series lacking the central Ala-Trp dipeptide of GHRP-1 (Raun et al., 1998)
- Species
- Not established by this molecular identity audit
- Termini (N / C)
- Not specified / Amide
Average reference mass
Reference policy updated: 2026-10-05
- PubChem molecular record · 2026-10-01
- Molecular formula
- C38H49N9O5
- Average reference mass
- ≈ 711.9
- Receptors
- Growth hormone secretagogue receptor 1a (GHS-R1a, the ghrelin receptor)
- Backbone
- Pentapeptide Aib-His-D-2-Nal-D-Phe-Lys-NH2, identified in a series lacking the central Ala-Trp dipeptide of GHRP-1 (Raun et al., 1998)
- C-terminus
- Amide
- Status
- Not approved anywhere. Two phase 2 trials (post-operative ileus, Helsinn) completed; no marketing application. WADA-prohibited.
Three of five residues are non-canonical: α-aminoisobutyric acid at position 1, D-2-naphthylalanine at position 3 and D-phenylalanine at position 4; C-terminal amide
- PubChem CID: 9831659
- CAS RN: 170851-70-4
- UNII: Y9M3S784Z6
Chemistry values: curated profile, PubChem · fetched 2026-10-01.
Clinical development snapshot
ClinicalTrials.gov lists 3 registered studies with “Ipamorelin” as an intervention (snapshot 2026-09-06). A registry footprint is not evidence of efficacy or approval.
| NCT | Title | Phase | Status | Updated |
|---|---|---|---|---|
| NCT07717866 | Trifecta Research Study | — | active not recruiting | 2026-07-21 |
| NCT00672074 | Safety and Efficacy of Ipamorelin for Management of Post-Operative Ileus | Phase 2 | completed | 2017-04-14 |
| NCT01280344 | Safety and Efficacy of Ipamorelin Compared to Placebo for the Recovery of Gastrointestinal Function | Phase 2 | completed | 2017-04-13 |
Ipamorelin — reconstitution calculator
Enter how much peptide is in the vial and how much diluent (e.g. bacteriostatic water) is added. The tool returns the resulting solution concentration — and, for any amount you type, the volume it corresponds to. This is educational arithmetic, not a dosing recommendation.
Reference form: Pentapeptide Aib-His-D-2-Nal-D-Phe-Lys-NH2, identified in a series lacking the central Ala-Trp dipeptide of GHRP-1 (Raun et al., 1998)Average reference mass: 711.9 Da
Enter an amount to see the volume it corresponds to.
Educational concentration mathematics only. This tool does not recommend a dose, amount, or protocol, and nothing here is medical advice. Many peptides are not authorized by Health Canada for human use — see our reconstitution and bacteriostatic-water guides for context.
Change log
Dated observations from the data pipeline (registry flags, trial footprints, identifiers) and editorial reviews of this profile.
- EditorialProfile content reviewed and updated by the editorial team.
FAQ about Ipamorelin
What is Ipamorelin?+
Ipamorelin (NNC 26-0161) is a synthetic pentapeptide — Aib-His-D-2-Nal-D-Phe-Lys-NH2 (C38H49N9O5, ≈712 Da) — developed by Novo Nordisk as the first growth hormone secretagogue that released growth hormone without stimulating ACTH or cortisol. It acts at the ghrelin receptor. It has never been approved: phase 2 trials in post-operative ileus were completed without a filing, and it is sold today as an unapproved research peptide and prohibited in sport.
What Canadian product status is recorded for Ipamorelin?+
Canadian product status for Ipamorelin has not been verified in this profile. No verified record here does not mean no authorization exists. Status depends on the product, formulation and use; consult Health Canada's product records.
What is the typical length of Ipamorelin?+
Ipamorelin is commonly described as approximately 5 amino acids (Growth hormone secretagogue (research compound)).
What is ipamorelin?+
A synthetic five-residue peptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) developed by Novo Nordisk that releases growth hormone by activating the ghrelin receptor, without stimulating ACTH or cortisol in the discovery studies.
Is ipamorelin approved?+
No, nowhere. Two phase 2 trials in post-operative ileus were completed without a marketing application. It is prohibited in sport.
What is ipamorelin's half-life?+
The evidence pack does not report a figure.
Ipamorelin vs CJC-1295 — what is the difference?+
Different receptors: ipamorelin acts at the ghrelin receptor, CJC-1295 at the GHRH receptor. No trial has tested the combination.
Ipamorelin vs MK-677?+
Both activate the ghrelin receptor. MK-677 is an oral small molecule with a long duration; ipamorelin is an injected pentapeptide. Neither is approved.
Does ipamorelin build muscle or burn fat?+
No human trial in the evidence pack tested that. The human data are two completed phase 2 trials in post-operative ileus with no published result.
What are ipamorelin's side effects?+
No systematic human safety data exist beyond the discovery pharmacology's finding of no cortisol or ACTH rise. Grey-market vials add unknowns of content and sterility.
Further reading
- ComparisonCJC-1295 vs Ipamorelin: Growth Hormone Secretagogue ComparisonAn educational comparison of CJC-1295 (a GHRH analog) and ipamorelin (a selective ghrelin/GHS-R agonist) as research compounds—receptors, selectivity, and framing. Not medical advice.
- GH secretagoguesIpamorelin vs GHRP-6: Selectivity, Appetite, and Receptor ProfilesHow ipamorelin and GHRP-6 differ as ghrelin-receptor growth-hormone secretagogues—selectivity, appetite and cortisol effects, and why researchers characterize them differently. Educational only.
- Hormone axisGH Secretagogue Peptides Explained: CJC-1295, Ipamorelin, GHRPsEducational overview of growth hormone secretagogue peptides—GHRH analogs vs GHRPs, DAC vs no DAC, receptors, and research context.
- Not a peptideIs MK-677 (Ibutamoren) a Peptide? No — It Is an Oral Small-Molecule Ghrelin Mimetic. What the Trials ShowedMK-677 (ibutamoren) is sold next to peptides and stacked with them, but it is a small synthetic molecule that activates the ghrelin receptor by mouth. This guide explains what it is, how it differs from GHRH and GHRP peptides, what its clinical trials showed — including the safety signal that stopped one — and its regulatory status.
- SafetyPeptide Safety and Risks: A Balanced Educational OverviewAn objective, balanced overview of what research does and does not establish about peptide risks—unknowns, purity and contamination concerns, and why unapproved compounds carry uncertainty. Not reassurance and not medical advice.
- FoundationsWhat Are Research Peptides? A Clear Educational GuideLearn what “research peptides” means, how they differ from approved peptide drugs, quality markers (COA, purity), and how to study them responsibly.
Related peptides
References & further reading
- 1.Raun et al. (1998). Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol
- 2.Johansen et al. (1999). Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats. Growth Horm IGF Res
- 3.Malmlöf et al. (1999). Methylprednisolone does not inhibit the release of growth hormone after intravenous injection of a novel growth hormone secretagogue in rats. Growth Horm IGF Res
- 4.Svensson et al. (2000). The GH secretagogues ipamorelin and GH-releasing peptide-6 increase bone mineral content in adult female rats. J Endocrinol
- 5.Andersen et al. (2001). The growth hormone secretagogue ipamorelin counteracts glucocorticoid-induced decrease in bone formation of adult rats. Growth Horm IGF Res
- 6.Venkova et al. (2009). Efficacy of ipamorelin, a novel ghrelin mimetic, in a rodent model of postoperative ileus. J Pharmacol Exp Ther
- 7.Greenwood-Van Meerveld et al. (2012). Efficacy of ipamorelin, a ghrelin mimetic, on gastric dysmotility in a rodent model of postoperative ileus. J Exp Pharmacol
- 8.Beck et al. (2014). 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
- 9.Broglio et al. (2002). Ghrelin: much more than a natural growth hormone secretagogue. Isr Med Assoc J
- 10.Halem et al. (2004). Novel analogs of ghrelin: physiological and clinical implications. Eur J Endocrinol
- 11.Fehrentz et al. (2002). Growth hormone secretagogues: past, present and future. IDrugs
- 12.Smith et al. (1993). A nonpeptidyl growth hormone secretagogue. Science
- 13.Kojima et al. (1999). Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature
- 14.Shin et al. (2015). Therapeutic applications of ghrelin agonists in the treatment of gastroparesis. Curr Gastroenterol Rep
- 15.Greenwood-Van Meerveld et al. (2011). Ghrelin as a target for gastrointestinal motility disorders. Peptides
- 16.Lu Z et al. (2024). The GHS-R1a agonists anamorelin and ipamorelin inhibit cisplatin-induced weight loss in ferrets. Physiology & Behavior
- 17.Tewari K et al. (2026). Peptide supplements and their therapeutic applications in sports medicine. American Journal of Sports Medicine
- 18.Mavrych V et al. (2026). Therapeutic peptides in gerontology: mechanisms and applications for healthy aging. Frontiers in Aging
- 19.Sinha DK et al. (2020). Beyond the androgen receptor: the role of growth hormone secretagogues in body composition in hypogonadal males. Translational Andrology and Urology
- 20.Coutinho LFD et al. (2026). A new era of doping? Peptide and peptide-analog drugs in sport and bodybuilding. Journal of Sports Medicine and Physical Fitness
- 21.PubChem — Ipamorelin