Ipamorelin at a glance
Ipamorelin is a synthetic pentapeptide, Aib-His-D-2Nal-D-Phe-Lys-NH₂, that Novo Nordisk developed under the code NNC 26-0161. It was designed from scratch and is not a piece of any human hormone. Three of its five building blocks are foreign to natural proteins: D-phenylalanine, D-2-naphthylalanine and alpha-aminoisobutyric acid (Aib). Those residues and the amide on the C-terminus give peptidases little to grip, which lets so small a molecule last in plasma.
By mechanism it belongs to the growth hormone (GH) secretagogues, the family of ghrelin receptor agonists that also includes GHRP-6 and GHRP-2.
- Five residues, 711.9 Da, agonist at GHS-R1a, the ghrelin receptor.
- Terminal half-life of about 2 hours after intravenous infusion in humans.
- Known for GH release without an ACTH or cortisol rise, shown in pigs in 1998.
- Reached phase 2 for postoperative ileus; never approved. King Peptides sells it only in a blend with CJC-1295.
How Ipamorelin works
GHS-R1a is found on pituitary somatotrophs and on hypothalamic neurons. At the pituitary, binding engages a phospholipase C pathway, calcium inside the cell rises and stored GH is pushed out. In the hypothalamus the same receptor lowers somatostatin tone, the brake that otherwise holds GH secretion back. GHRH analogues reach the somatotroph by a different receptor, which explains why the two families are so often examined together.
The family has an odd chronology. The GH-releasing peptides were made in the 1980s, their receptor was identified in 1996, and ghrelin, the natural ligand, was described in 1999.
Agonists of this receptor seldom confine themselves to GH. The receptor also sits on cells that regulate appetite, and the older peptides push ACTH, cortisol and prolactin up a little. Ipamorelin came out of a screening programme that looked for the opposite: a full GH response that leaves those other hormones untouched. With a half-life near two hours, its effect resembles a pulse more than the plateau produced by a long-acting GHRH analogue such as CJC-1295 with DAC.
The evidence ladder for Ipamorelin
| Evidence level | Model or trial | Main finding |
|---|---|---|
| Animal study | Swine; Raun et al. (1998, European Journal of Endocrinology) | Dose-related GH release, efficacy in the range of GHRP-6; no meaningful ACTH or cortisol rise even at more than 200 times the half-maximal GH dose |
| Human pharmacology | Healthy adults, intravenous infusion | Terminal half-life of about 2 hours |
| Clinical trial, phase 2 | Patients with postoperative ileus after abdominal surgery | Programme stopped at phase 2; no phase 3, no approval |
The pig result is clean, and it remains a pig result. No published human study has drawn the same dose-response curve for cortisol. The clinical programme did not even pursue an endocrine goal. Because agonists of the ghrelin receptor accelerate gastric emptying and bowel movement, ipamorelin was tried against the standstill of the gut that follows abdominal surgery.
What is missing matters more. No controlled human trial has tested ipamorelin for physical performance, bone density, body composition or the repair of muscle and tendon. The GH rise is well documented; what it leads to in people over weeks is not. A page that promises lean mass is advertising.
Ipamorelin doses reported in studies
The table gives reference descriptions of published work, not guidance. Our sources report designs, not absolute figures, and no validated human dose exists.
| Setting | Dose | Route | Note |
|---|---|---|---|
| Raun et al. (1998), swine | Scaled to the half-maximal GH dose, up to more than 200 times that dose | Intravenous | GH rose with dose; ACTH and cortisol did not move |
| Human pharmacology, healthy adults | Not quoted in our sources | Intravenous infusion | Terminal half-life about 2 hours |
| Phase 2, postoperative ileus | Hospital schedules set for a surgical indication; not quoted | Intravenous | Bowel recovery as endpoint; development ended |
The animal figures are given per kilogram of body weight and as multiples of a reference dose inside the study, which helps when peptides are compared and for nothing else. Microgram schedules found on supplier pages do not come from these studies and are left out.
Safety findings and open questions
No long-term human safety data exist. GH works against insulin, and in human studies ghrelin receptor agonists acutely reduce insulin secretion; both effects push blood glucose upwards, and nobody has dosed people with ipamorelin for months. Oedema, aching joints and carpal tunnel complaints come with sustained GH excess and are class concerns, not observations from ipamorelin trials. A research vial holds lyophilised powder; it is not a licensed sterile preparation for human or veterinary use.
- Does the missing ACTH and cortisol response seen in swine hold in humans across the dose range?
- Appetite: the receptor drives hunger and GHRP-6 is strongly orexigenic. Appetite is not prominent in the ipamorelin literature, yet it has not been ruled out.
- What happens to glucose handling with exposure over weeks or months?
- What does the GH rise produce downstream in people? No controlled trial has asked.
Bench notes: storing and reconstituting Ipamorelin
The powder is lyophilised and is stored at −20 °C in a closed vial, away from light and moisture. A vial from the freezer should warm to room temperature before it is opened, so that water from the air does not settle on the cake.
Because the shop sells ipamorelin only blended with CJC-1295, a solution prepared from that vial holds both peptides. Bacteriostatic water is the customary solvent for a vial sampled repeatedly. Add it slowly along the wall, swirl without shaking and look for a clear liquid. Solutions go in the refrigerator in the dark; portions for later are frozen once and thawed once. Note the lot number and date on each tube. The bench protocol for storage and reconstitution has the details.
Status in the Netherlands, Belgium and Luxembourg
EU marketing authorisations come from the European Medicines Agency and hold in the Netherlands, Belgium and Luxembourg alike. Ipamorelin has none, there or anywhere else: development stopped at phase 2 and no regulator has assessed a dossier. What is sold as a research peptide is not a medicine and not for human use. National and institutional rules on possession and personal import differ and must be checked.
For athletes: section S2 of the WADA Prohibited List names growth hormone secretagogues, ipamorelin among them. S2 applies at all times, in competition and out of it. How ipamorelin compares with hexarelin and the GHRPs is set out in GH secretagogues compared.
Ordering Ipamorelin for research in the Benelux
Ipamorelin is not available from King Peptides as a separate vial. The shop offers it in a single blend product, CJC-1295 + Ipamorelin Blend 5/5 mg, where it is combined with a GHRH analogue.
Read the lot-specific certificate of analysis, which shows HPLC and mass spectrometry results, with both components in mind. Ipamorelin is light for a peptide, so its mass signal should sit at 711.9 Da, far below that of the CJC-1295 component. Purity by HPLC should be stated as 99% or higher, and the lot number on the certificate must equal the one on the vial. The guide to checking a certificate of analysis explains each line.
Dispatch is from the Netherlands by tracked parcel. Expect 1–2 business days within the Netherlands as a rule and 3–5 business days to Belgium or Luxembourg; no customs clearance applies inside the EU. More on suppliers in buying research peptides in the Benelux.
Ipamorelin: quick answers
Is ipamorelin derived from ghrelin? No. It is a designed pentapeptide that activates the receptor ghrelin uses; its sequence is also unrelated to GHRP-6 and GHRP-2.
Has the cortisol finding been confirmed in people? Not as a dose-response curve. The selectivity is well supported in swine and assumed in humans.
What was it tested for in patients? Postoperative ileus. The programme got as far as phase 2 and ended there; no licensed product or approved indication resulted.
Can I order ipamorelin on its own? Not from King Peptides; it is listed only in the blend with CJC-1295.
Why is it combined with a GHRH analogue? The two act through different receptors on the same cell, and together they release more GH than either alone. See peptide combinations.
Research use only. This page describes Ipamorelin for laboratory and scientific research. Research material has no marketing authorisation, whatever the status of the molecule as a medicine elsewhere, and is not meant for human or veterinary use. Nothing on this page is medical advice; the doses above are those reported in published studies, not recommendations. Check the rules that apply in your country and at your institution before ordering.