Scientific Reference
Ipamorelin
Evidence profile: Human Phase 2 evidence
What made Ipamorelin interesting in its original animal pharmacology was what it did not do. Older growth hormone-releasing peptides raised ACTH and cortisol alongside growth hormone; in those studies this one did not, and that selectivity is the reason it is still discussed. It is a synthetic pentapeptide, Aib-His-D-2-Nal-D-Phe-Lys-NH2, derived from the earlier compounds in the class and a residue shorter than both GHRP-2 and GHRP-6, acting as an agonist at the ghrelin receptor GHS-R1a. Because that receptor also sits in the gut, rodent models of gastrointestinal motility have used it as well. A small number of human clinical studies exist; the bulk of what is known is animal work, and human data remain limited.
Mechanism of Action
The reported binding site is GHS-R1a on the somatotroph cells of the anterior pituitary, where activating the receptor raises intracellular calcium and growth hormone is secreted. The selectivity claim is specifically about other pituitary and adrenal hormones: in the animal studies that first characterised the compound, ACTH and cortisol did not rise to any appreciable degree, which was not the case for GHRP-6 or GHRP-2. Why the structure should produce that difference has not been fully explained. The same receptor is present in the gut wall and in the nerves supplying it, which is the stated rationale for the rodent transit studies.
Molecular Information
- Type: Growth hormone secretagogue (GHRP)
- Molecular weight: 711.9 g/mol
- Molecular formula: C38H49N9O5
- CAS: 170851-70-4
Published Research
Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients
Beck DE et al. · International journal of colorectal disease · 2014 · Clinical
PMID 25331030 — View on PubMedPharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers
Gobburu JV et al. · Pharmaceutical research · 1999 · Clinical
PMID 10496658 — View on PubMed