Last reviewed: October 2026 · Cleared Peptides research team
Ipamorelin (NNC 26-0161) is a synthetic pentapeptide described in 1998 as a selective agonist of the growth-hormone secretagogue receptor (GHS-R1a), the receptor for ghrelin. It is a reference ligand in GHS-R binding and signaling research.
In this guide:
Ipamorelin Structure and Identifiers
| Name | Ipamorelin |
|---|---|
| Code | NNC 26-0161 |
| CAS number | 170851-70-4 |
| PubChem CID | 9831659 |
| Molecular formula | C38H49N9O5 |
| Molecular weight | ≈711.9 g/mol |
| Sequence | Aib-His-D-2-Nal-D-Phe-Lys-NH2 |
| Form | Lyophilized powder |
Receptor Pharmacology
Ipamorelin belongs to the growth-hormone-releasing peptide (GHRP) family but was designed for greater receptor selectivity than earlier GHRPs such as GHRP-6. It contains non-coded residues — α-aminoisobutyric acid (Aib) and D-2-naphthylalanine — that increase stability and receptor affinity. In research it is used to study GHS-R1a activation, Gq/calcium signaling and receptor desensitization.
Ipamorelin vs GHRH Analogs
| Ipamorelin | Tesamorelin | |
|---|---|---|
| Receptor | GHS-R1a (ghrelin receptor) | GHRH receptor |
| Length | 5 residues | 44 residues |
| CAS | 170851-70-4 | 218949-48-5 |
| Product | Ipamorelin | Tesamorelin |
Because the two act through different receptors, they are commonly compared in receptor-pharmacology studies. This summary describes laboratory research only and makes no claim about effects in humans or animals.
Research materials referenced in this guide
Frequently Asked Questions
What receptor does ipamorelin act on?
Ipamorelin is characterized as a selective agonist of GHS-R1a, the ghrelin receptor.
What is the CAS number of ipamorelin?
170851-70-4; molecular formula C38H49N9O5.
Is ipamorelin for human use?
No. It is supplied for laboratory research use only.
Selected References
Peer-reviewed literature on the compounds discussed in this guide, listed as scientific background for laboratory researchers. Citation does not imply endorsement by the authors or any use other than in-vitro research.
- Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552-61. PubMed 9849822 · DOI
- Ankersen M, et al. A new series of highly potent growth hormone-releasing peptides derived from ipamorelin. J Med Chem. 1998;41(19):3699-704. PubMed 9733495 · DOI
Laboratory note: solubility depends on salt form and solvent. This guide does not state a single solubility figure. Handling of lyophilized material is described in the peptide storage guide.
Research Use Only Notice
This guide is provided for educational and laboratory reference purposes. It summarizes published, primarily in-vitro and structural research literature and does not describe, recommend or imply any use in humans or animals. Products sold by Cleared Peptides are for laboratory research use only; they are not drugs, foods, cosmetics or dietary supplements, are not FDA-approved, and are not intended to diagnose, treat, cure, mitigate or prevent any disease. No dosing, administration or therapeutic information is provided.
