Ipamorelin Research

Overview

What is ipamorelin?

Ipamorelin is the pentapeptide Aib-His-D-2-Nal-D-Phe-Lys-NH2, developed at Novo Nordisk as NNC 26-0161. Its identity, origin, receptor target and status.

By the Ipamorelin Research editorial team · Last reviewed · Scientific review: pending

Short answer

Ipamorelin is a synthetic pentapeptide, Aib-His-D-2-Nal-D-Phe-Lys-NH2, developed at Novo Nordisk as NNC 26-0161 and first described in 1998. It is a growth hormone secretagogue: it activates the GHSR-1a receptor, the receptor for the body's own hormone ghrelin, which causes the pituitary to release a pulse of growth hormone. It is not an approved drug anywhere in the United States, and it was investigated clinically only for recovery of gut function after abdominal surgery.

Scientific identity

Ipamorelin is a chain of five amino acids ending in an amide group rather than the free acid that terminates an ordinary peptide [PubChem]. Three of the five residues are not standard L-amino acids: the first is 2-aminoisobutyric acid, a residue that does not occur in ordinary proteins, and the third and fourth are a naphthylalanine and a phenylalanine in the D configuration. Those unnatural residues are the reason the peptide resists ordinary proteolysis, and they are also the reason FDA has described characterising it as complex [FDA Category 2].

It is registered in the FDA Global Substance Registration System under UNII Y9M3S784Z6[FDA GSRS], and carries CAS number 170851-70-4 and PubChem CID 9831659[PubChem]. Its full molecular record is on the molecular data page.

Where it came from

Ipamorelin was the product of a medicinal chemistry programme at Novo Nordisk searching for compounds that would make the pituitary release growth hormone. It was identified within a series derived by removing the central Ala-Trp dipeptide from growth hormone-releasing peptide-1 [Raun 1998]. The same programme then used ipamorelin as a starting point for further analogues aimed at oral activity, producing NNC 26-0235, NNC 26-0194 and ultimately NN703, which entered phase 2 trials [Ankersen 1998] [Hansen 1998] [Hansen 1999].

What it targets

Ipamorelin acts at the growth hormone secretagogue receptor GHSR-1a. This was established pharmacologically rather than assumed: profiling with GHRP and GHRH antagonists showed that ipamorelin stimulates growth hormone release through a GHRP-like receptor and not through the separate GHRH receptor [Raun 1998]. That distinction matters when ipamorelin is compared with sermorelin, tesamorelin or CJC-1295, which are all GHRH analogues acting at the other receptor. The full pathway is set out on the mechanism page.

What it has actually been studied for

The preclinical literature covers growth hormone release, bone growth and bone mineral content, body composition, nitrogen balance during glucocorticoid treatment, insulin release from excised pancreatic tissue, gastrointestinal motility, visceral pain behaviour and reproductive endpoints in fish. The 3 human records cover pharmacokinetics and growth hormone response in healthy men [Gobburu 1999], recovery of gut function after bowel surgery [Beck 2014], and urinary metabolites after intranasal administration in a single volunteer.

The only clinical indication ever pursued was postoperative ileus. No trial has ever tested ipamorelin for muscle growth, fat loss, recovery, sleep or ageing, and no human study has measured any of those endpoints.

Regulatory position in brief

There is no approved application for ipamorelin in Drugs@FDA [openFDA]. FDA has placed ipamorelin acetate in Category 2 of bulk substances that may present significant safety risks when used in compounding [FDA Category 2], and an FDA advisory committee voted against adding it to the 503A Bulks List in October 2024. The regulatory status page sets out the record in full, including the vote tallies.

References

  1. Raun K, Hansen BS, Johansen NL et al. (1998). Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. PubMed 9849822 · doi:10.1530/eje.0.1390552[Animal, grade C]
  2. Ankersen M, Johansen NL, Madsen K et al. (1998). A new series of highly potent growth hormone-releasing peptides derived from ipamorelin. J Med Chem. PubMed 9733495 · doi:10.1021/jm9801962[Animal, grade C]
  3. Hansen TK, Ankersen M, Hansen BS et al. (1998). Novel orally active growth hormone secretagogues. J Med Chem. PubMed 9733496 · doi:10.1021/jm980197u[Animal, grade C]
  4. Hansen BS, Raun K, Nielsen KK et al. (1999). Pharmacological characterisation of a new oral GH secretagogue, NN703. Eur J Endocrinol. PubMed 10427162 · doi:10.1530/eje.0.1410180[Animal, grade C]
  5. Johansen PB, Hansen KT, Andersen JV et al. (1998). Pharmacokinetic evaluation of ipamorelin and other peptidyl growth hormone secretagogues with emphasis on nasal absorption. Xenobiotica. PubMed 9879640 · doi:10.1080/004982598238976[Animal, grade C]
  6. Gobburu JV, Agersø H, Jusko WJ et al. (1999). Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharm Res. PubMed 10496658 · doi:10.1023/a:1018955126402[Human, grade B]
  7. Beck DE, Sweeney WB, McCarter MD et al. (2014). Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients. Int J Colorectal Dis. PubMed 25331030 · doi:10.1007/s00384-014-2030-8[Human, grade A]
  8. PubChem, National Library of Medicine. Ipamorelin (CID 9831659). Source[retrieved 2026-11-11]
  9. FDA Global Substance Registration System. IPAMORELIN, UNII Y9M3S784Z6. Source[retrieved 2026-11-11]
  10. U.S. Food and Drug Administration (2026-04-22). Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks. Source[retrieved 2026-11-11]
  11. U.S. Food and Drug Administration, openFDA. openFDA Drugs@FDA and NDC directory queries for ipamorelin. Source[retrieved 2026-11-11]