Ipamorelin
GH secretagogue
A selective growth-hormone secretagogue (ghrelin-receptor agonist) used in research on growth-hormone release with minimal effect on other hormones.
Mechanism#
A selective ghrelin-receptor agonist that triggers a clean pulse of growth hormone without strongly affecting cortisol or prolactin — making it a 'cleaner' secretagogue for GH-axis research.
Areas of research#
- Growth-hormone pulsatility
- Ghrelin-receptor signalling
- GH/IGF-1 axis research
- Selective secretagogue pharmacology
Identity and specification#
| Also known as | NNC 26-0161 |
|---|---|
| Sequence | Aib-His-D-2-Nal-D-Phe-Lys-NH2 |
| Length | 5 residues (pentapeptide), C-terminally amidated |
| Molecular formula | C38H49N9O5 |
| Molecular weight | 711.86 g/mol |
| CAS number | 170851-70-4 |
| Class | Synthetic pentapeptide; selective ghrelin receptor (GHS-R1a) agonist |
| Appearance | White lyophilised powder |
| Solubility | Bacteriostatic or sterile water |
| Storage | 2–8°C, both sealed and once in solution |
Ipamorelin is a pentapeptide where GHRP-2 and GHRP-6 are hexapeptides, and at 711.86 it is the smallest of the three by a clear margin — roughly 106 mass units below GHRP-2 and 161 below GHRP-6. On a mass spectrum the three are unmistakable from one another.
The first residue is the interesting one. Aib is α-aminoisobutyric acid: alanine with a second methyl group on the alpha carbon. It is not one of the twenty proteinogenic amino acids, and it cannot be encoded biologically. Two methyls on the same carbon leave a protease nothing to approach from, and they constrain the backbone into a tight helical turn, so the residue does two jobs at once: it stabilises the molecule and it holds the rest of the chain in the shape the receptor reads.
The shared feature with GHRP-2 is D-2-naphthylalanine at position 3 — the bulky aromatic group that sits in the receptor pocket, and the part of the pharmacophore the whole secretagogue family is built around. What Ipamorelin lacks, and GHRP-6 has, is the tryptophan-rich character associated in the literature with activity beyond the GH axis; that difference is the basis of the selectivity this compound is usually studied for.
Handling and storage#
Supplied as a lyophilised cake. Add solvent slowly down the vial wall and swirl rather than shake. Keep the sealed vial at 2–8°C; once in solution, refrigerate at 2–8°C, keep it out of the light and avoid repeated freeze-thaw cycles.
For how the secretagogue family compares, residue by residue, see our guide to GHRP-2 and GHRP-6.
Sizes and pricing#
| Size | Price per vial | Availability |
|---|---|---|
| 2mg | £9 | Made to order — 1-2 weeks |
| 5mg | £20 | Made to order — 1-2 weeks |
| 10mg | £34 | In stock |
Buying more than one? Mix and match any peptide vials: 3 vials 8%, 5 vials 12%, 10 or more 15% off the peptides in your basket. You get whichever is better, the bulk or the volume discount, never both — applied automatically at checkout. How it works.
Batch documentation. Ask about the documentation for the batch we would ship before you order.
Check your certificate#
- Molecular weight 711.86 (monoisotopic 711.39). On a mass spectrum, expect the singly charged ion near 712.4 or the doubly charged ion near 356.7. The certificate should say which.
- Not the glycine-extended variant. Anti-doping laboratories found ipamorelin with an extra glycine on the front in seized black-market products in 2018. It is 57 heavier: a mass near 768–769 is not ipamorelin.
- Not GHRP-2 or GHRP-6. At 817.99 and 873.03 they are about 106 and 161 heavier, so on a mass spectrum the three cannot be confused.
- An amide at the C-terminus. Ipamorelin ends in Lys-NH2, not a free acid. The formula should read C38H49N9O5.
- Purity, with the method named, measured on that batch rather than quoted as a minimum.
Ask about the documentation for the batch we would ship before you order. How to check a certificate yourself: verifying a COA.
What’s in the vial#
| Fill | 2mg, 5mg or 10mg of peptide per vial |
|---|---|
| Appearance | White lyophilised powder |
| Purity and content | Purity is the share of what was detected that is this peptide. Net peptide content, how much of the powder’s weight is peptide rather than salt and water, is a separate number. How much is in the vial. |
Handling at a glance#
| Solvent | Bacteriostatic or sterile water |
|---|---|
| Sealed vial | 2–8°C, dry and dark. Let it reach room temperature before opening. |
| Once in solution | 2–8°C and out of the light. Avoid thawing and refreezing the same volume. |
| Worth knowing | The first residue, Aib (α-aminoisobutyric acid), is not one of the twenty amino acids biology uses. Its two methyl groups stiffen the backbone and leave proteases little to cut. |
Working out a concentration: the reconstitution calculator. Technique: the reconstitution guide and the storage guide.
What the research covers#
The core research is small and from the late 1990s: the 1998 Novo Nordisk paper comparing ipamorelin with GHRP-2 and GHRP-6 in rat pituitary cells, rats and pigs, a 1998 rat pharmacokinetic study, and a 1999 study in healthy men that measured a half-life of about two hours. “Selective” refers to one finding in pigs: it did not raise ACTH or cortisol above the level seen with GHRH itself, where GHRP-2 and GHRP-6 did. A 2014 phase 2 trial in 117 patients after bowel surgery found no statistically significant difference from placebo on its main measure. It is not a licensed medicine anywhere. Read the full guide, with sources: Ipamorelin: What “Selective” Actually Means.
Published literature#
- Raun K, Hansen BS, Johansen NL, et al. (1998). Eur J Endocrinol 139(5):552–61. The Novo Nordisk paper that first described ipamorelin, comparing it with GHRP-2 and GHRP-6 in rat pituitary cells, rats and pigs, including ACTH and cortisol. PubMed 9849822
- Johansen PB, Hansen KT, Andersen JV, et al. (1998). Xenobiotica 28(11):1083–92. Rat pharmacokinetics of ipamorelin compared with GHRP-2 and GHRP-6: clearance, routes of excretion, and absorption through the nasal lining. PubMed 9879640
- Gobburu JV, Agersø H, Jusko WJ, et al. (1999). Pharm Res 16(9):1412–6. Study in healthy men at five infusion levels, modelling ipamorelin’s half-life and the growth hormone pulse that followed. PubMed 10496658
- Semenistaya E, Zvereva I, Thomas A, et al. (2015). Drug Test Anal 7(10):919–25. Anti-doping study of how ipamorelin and four related GHRPs are broken down and excreted, noting that they are on the WADA Prohibited List. PubMed 25869809
Listed so the work can be read at source. A paper on this list is evidence of what was studied, not of what any product does.
Questions#
What is ipamorelin?
A synthetic pentapeptide, Aib-His-D-2-Nal-D-Phe-Lys-NH2, that acts at the ghrelin receptor (GHS-R1a). It was designed at Novo Nordisk and first described in 1998.
What molecular weight should the certificate show?
711.86 (monoisotopic 711.39), usually seen as ions near 712.4 or 356.7. A mass near 768 to 769 is a glycine-extended variant, and 817.99 is GHRP-2.
What does selective mean here?
It refers to a 1998 finding in pigs: ipamorelin released growth hormone without the ACTH and cortisol rise that GHRP-2 and GHRP-6 produced. It does not mean it is more potent.
How should it be stored?
Sealed vial at 2-8°C, dry and dark. Once reconstituted with bacteriostatic or sterile water, keep it at 2-8°C and out of the light, and avoid thawing and refreezing the same volume.
Is it for human use?
No. It is supplied for laboratory research only, and we do not give guidance on human or animal use.
A batch-specific Certificate of Analysis is available on request. New to handling lyophilised material? See our reconstitution guide, storage guide and how to read a COA.