Ipamorelin: Structure, Research Overview and Specifications
Ipamorelin is a synthetic pentapeptide that acts as a selective agonist of the ghrelin receptor (growth hormone secretagogue receptor, GHS-R1a). It was described in 1998 as the first selective growth hormone secretagogue, because in early studies it stimulated growth hormone release without the marked rises in ACTH and cortisol seen with earlier compounds. This page summarises its chemistry, mechanism, published research and the specifications of the material we supply.
For in vitro research use only. Not for human or animal use. Nothing on this page is medical advice.
What is ipamorelin?
Ipamorelin belongs to the growth hormone secretagogue (GHS) family: compounds that stimulate the pituitary gland to release its own growth hormone. Unlike GHRH analogues such as tesamorelin, which act on the GHRH receptor, ipamorelin acts on the ghrelin receptor, the same receptor targeted by the natural “hunger hormone” ghrelin.
Its main interest in research is its selectivity. Earlier growth hormone-releasing peptides, such as GHRP-6 and GHRP-2, also raised ACTH, cortisol and prolactin. Ipamorelin was designed and characterised as a more selective tool for studying the GH axis.
Chemical data
| Name | Ipamorelin (NNC 26-0161) |
|---|---|
| Sequence | Aib-His-D-2-Nal-D-Phe-Lys-NH2 |
| Length | 5 amino acids (pentapeptide), including non-standard residues (Aib, D-2-naphthylalanine) |
| Molecular formula | C38H49N9O5 |
| Molecular weight | ≈ 711.9 g/mol |
| CAS number | 170851-70-4 |
| Appearance | White lyophilised powder |
| Available sizes | Ipamorelin 5mg |
Development history
Ipamorelin was developed by Novo Nordisk under the code NNC 26-0161 and characterised in a 1998 paper in the European Journal of Endocrinology (Raun et al.). It was later investigated in phase 2 clinical trials for postoperative ileus (slowed gut function after surgery), but development was discontinued because of a lack of efficacy. It has never been approved as a medicine.
Mechanism of action
- Ghrelin receptor agonism. Ipamorelin binds GHS-R1a on pituitary cells and stimulates pulsatile release of endogenous growth hormone.
- Selectivity. In the original characterisation, GH release was not accompanied by marked increases in ACTH, cortisol or prolactin, unlike with GHRP-6 and GHRP-2.
- Complementary to GHRH. Ghrelin-receptor agonists and GHRH analogues act through different receptors, which is why they are often studied together, for example in CJC-1295 + ipamorelin research.
- Gut motility. Ghrelin receptors are also present in the gastrointestinal tract, which was the basis for its investigation in postoperative ileus.
What the published research shows
Original characterisation
Raun et al. (1998) compared ipamorelin with other growth hormone secretagogues in animal models. They reported potent, dose-dependent GH release with a selectivity profile that set it apart from earlier GHRPs, describing it as “the first selective growth hormone secretagogue”.
Clinical investigation
Phase 2 trials explored ipamorelin for the management of postoperative ileus. These studies did not show sufficient benefit, and clinical development was stopped.
Research use today
Ipamorelin is used in laboratory research as a selective tool for studying ghrelin-receptor signalling and the regulation of pulsatile growth hormone release.
Limitations of the evidence
- Much of the selectivity data comes from animal models in the late 1990s.
- The only completed clinical programme (postoperative ileus) did not show efficacy.
- There are no long-term human safety data.
Regulatory status
Ipamorelin is not a licensed medicine in the UK and has not been approved by the MHRA, FDA or EMA. Growth hormone secretagogues, including ghrelin-receptor agonists, are prohibited in sport under the WADA Prohibited List (S2). Sterling Research supplies ipamorelin only as a research reagent for in vitro laboratory use. It must not be used in humans or animals.
Storage and handling in the lab
- Store lyophilised powder at −20 °C, sealed and protected from light and moisture.
- Let the vial reach room temperature before opening to limit condensation.
- Prepare solutions to your laboratory’s validated protocols, with appropriate PPE and aseptic technique.
- Avoid repeated freeze–thaw cycles of solutions. Aliquot where your protocol allows.
Quality
Every batch of ipamorelin we supply is independently tested by Janoshik for purity and identity before it is released for sale.
Related research compounds
Frequently asked questions
What type of peptide is ipamorelin?
Ipamorelin is a synthetic pentapeptide growth hormone secretagogue that acts as a selective agonist of the ghrelin receptor (GHS-R1a).
Why is ipamorelin called selective?
In its original characterisation, ipamorelin stimulated growth hormone release without the marked increases in ACTH, cortisol and prolactin seen with earlier secretagogues such as GHRP-6 and GHRP-2.
What is the difference between ipamorelin and tesamorelin?
Both stimulate the release of the body’s own growth hormone, but through different receptors. Ipamorelin acts on the ghrelin receptor, while tesamorelin is a GHRH analogue that acts on the GHRH receptor.
Why is ipamorelin often studied with CJC-1295?
CJC-1295 is a GHRH analogue and ipamorelin is a ghrelin-receptor agonist. Because they act through different receptors, researchers study them together to examine how the two pathways interact in regulating growth hormone release.
Is ipamorelin approved as a medicine?
No. It reached phase 2 trials for postoperative ileus but development was discontinued. It is not approved by the MHRA, FDA or EMA.
References
- Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552–561. PubMed 9849822
- Ipamorelin. Overview, development history and chemical identifiers
This page is for scientific information only. Sterling Research Group Ltd supplies ipamorelin strictly for in vitro laboratory research. Not for human or animal use, and not for diagnostic or therapeutic purposes.