Ipamorelin and GHRP-2 compared: chemistry, targets and regulatory records
Ipamorelin and GHRP-2 are both synthetic growth hormone secretagogues acting at the growth hormone secretagogue receptor. Ipamorelin is a pentapeptide and GHRP-2 a hexapeptide.
Research-use information. This page summarises published literature and regulator records. It is not guidance for use, not medical advice, and not a statement that any material is suitable for use in people or animals.
How do Ipamorelin and GHRP-2 differ on the facts?
| Fact | Ipamorelin | GHRP-2 |
|---|---|---|
| Class | Pentapeptide growth hormone secretagogue | Hexapeptide growth hormone secretagogue |
| Length | 5 residues | 6 residues |
| Molecular formula | C38H49N9O5 | C45H55N9O6 |
| Average molecular weight | 711.9 g/mol | 818 g/mol |
| Receptor or pathway background | Growth hormone secretagogue receptor | Growth hormone secretagogue receptor |
| FDA (Drugs@FDA) | No application listed | No application listed |
| EMA (centrally authorised) | No centrally authorised medicine listed | No centrally authorised medicine listed |
| MHRA (Products) | No product document found | No product document found |
| WADA 2026 list | Named, S2.2.4 | Named, S2.2.4 |
| Studies in our library | 7 | 4 |
| PubMed records for the search terms | 50 | 237 |
| Registered studies (ClinicalTrials.gov) | 3 | 0 |
Data dates: chemistry checked against PubChem 2026-10-05; regulatory records 2026-10-05; WADA list 2026-10-05; PubMed counts 2026-10-05.
What do the cited papers say differs between Ipamorelin and GHRP-2?
- Ipamorelin was identified in a series of compounds lacking the central Ala-Trp dipeptide of growth hormone-releasing peptide; GHRP-2 retains an Ala-Trp unit in its sequence.[5]
- Both contain D-2-naphthylalanine and D-phenylalanine residues (from the catalog sequences).
- GHRP-2 has diagnostic-test papers in pituitary endocrinology; ipamorelin has a pharmacokinetic study in volunteers and rat studies.[1],[2],[3],[4]
Nothing on this page ranks one compound above the other or states what either does for a person.
Which studies are cited on this page?
[1] Teramoto S, Tahara S, Hattori Y, Kondo A, Morita A. Assessment of anterior pituitary reserve capacity based on growth hormone response to growth hormone-releasing peptide-2 test in the elderly. Growth Horm IGF Res. 2023;71:101545.
Analysed growth hormone response to the GHRP-2 diagnostic test in 65 elderly patients with a non-functioning pituitary tumour.
[2] Suzuki S, Ruike Y, Ishiwata K, Naito K, Igarashi K, Ishida A, et al.. Clinical Usefulness of the Growth Hormone-Releasing Peptide-2 Test for Hypothalamic-Pituitary Disorder. J Endocr Soc. 2022;6:bvac088.
Evaluated the GHRP-2 test as a diagnostic test in patients with hypothalamic-pituitary disorder, including its ACTH response.
[3] Gobburu JV, Agersø H, Jusko WJ, Ynddal L. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharm Res. 1999;16:1412-6.
Pharmacokinetic and pharmacodynamic modelling of ipamorelin and growth hormone concentrations in healthy volunteers.
[4] Johansen PB, Nowak J, Skjaerbaek C, Flyvbjerg A, Andreassen TT, Wilken M, et al.. Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats. Growth Horm IGF Res. 1999;9:106-13.
Measured longitudinal bone growth rate, body weight and growth hormone release in adult female rats.
[5] Raun K, Hansen BS, Johansen NL, Thøgersen H, Madsen K, Ankersen M, et al.. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139:552-61.
Describes the pharmacology of ipamorelin: growth hormone release in vitro and in animals, and selectivity against other pituitary hormones.