Entry 0009Rev 1.0Growth hormone secretagogue

Ipamorelin

Aib-His-D-2Nal-D-Phe-Lys-NH2 · C38H49N9O5

Reviewed

2 Nov 2026

Scientific editor

[Name, PhD]

References

5 sources

Ipamorelin is a five-residue synthetic peptide, made at Novo Nordisk in the 1990s from an earlier growth hormone-releasing peptide. It acts on the ghrelin receptor and releases growth hormone from the pituitary.1

Its selling point in the original paper was selectivity: at doses that released growth hormone in animals, it did not raise cortisol or ACTH as older peptides did. Its one clinical programme, for gut paralysis after surgery, was stopped for lack of effect.3

Residues

5

Avg mass

711.9 g/mol

Phase 2 outcome

Stopped

WADA class

S2.2.4

01

Identity

Three of the five residues are not standard amino acids: aminoisobutyric acid at the start, and D-forms of naphthylalanine and phenylalanine in the middle. The C-terminus is an amide.

Fig. 1 · Sequence map. Non-standard and D-form residues shaded.

Value
DeveloperNovo Nordisk
CodeNNC 26-0161
ReceptorGhrelin receptor (GHS-R1a)
FormulaC38H49N9O5
Avg mass711.9 g/mol
CAS170851-70-4
02

History

  1. Raun and colleagues describe it as the first selective growth hormone secretagogue.1

  2. Pharmacokinetic study in healthy volunteers; bone growth study in rats.2,4

  3. Phase 2 trial in postoperative ileus after bowel surgery reports no benefit; programme discontinued.3

  4. Named on the WADA list as a growth hormone secretagogue.5

03

What the studies measured

AreaModelWhat was measuredSource
SelectivityPigs and rat pituitary cellsGrowth hormone release, and whether ACTH, cortisol and prolactin rose with it[1]
PharmacokineticsHealthy volunteersBlood levels and growth hormone response over time, modelled together[2]
GutAdults after bowel resection, randomisedTime to recovery of gut function[3]
BoneYoung ratsLongitudinal bone growth[4]
04

Regulatory and sport status

WhereStatus
UK, EU, USNot approved anywhere. Not a controlled drug in the UK. May not be supplied or promoted for human use.
SportProhibited at all times. Named in WADA class S2.2.4 among "growth hormone secretagogues (GHS) and their mimetics".5
05

Open questions

  1. Whether the selectivity seen in animals holds at other doses and in people over time.
  2. Why the ileus trial failed when the animal gut work looked promising.
  3. Long-term effects of raised growth hormone and IGF-1, which no study has measured.
06

Common questions

What is ipamorelin?

A five-residue synthetic peptide that releases growth hormone by acting on the ghrelin receptor.

What does "selective" mean here?

In the original animal studies it released growth hormone without the rise in cortisol and ACTH seen with older peptides such as GHRP-6.

Has ipamorelin been tested in people?

Yes, in a pharmacokinetic study and a phase 2 trial for gut paralysis after surgery. The trial showed no benefit and the programme was stopped.

Is ipamorelin banned in sport?

Yes, by name, under WADA class S2.2.4, at all times.

How is it different from CJC-1295?

Different receptor. Ipamorelin acts on the ghrelin receptor; CJC-1295 is a GHRH analogue acting on the GHRH receptor.

—

See also

CJC-1295 Entry 0010Tesamorelin Entry 0004Growth hormone axis ShelfIpamorelin vs CJC-1295 Comparison
07

References

  1. Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552–561. PMID 9849822
  2. Gobburu JV, et al. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharm Res. 1999;16(9):1412–1416. PMID 10496658
  3. Beck DE, Sweeney WB, McCarter MD. 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. 2014;29(12):1527–1534. PMID 25331030
  4. Johansen PB, et al. Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats. Growth Horm IGF Res. 1999;9(2):106–113. PMID 10373343
  5. World Anti-Doping Agency. The 2026 Prohibited List. wada-ama.org Class S2.2.4.

Peptidarium Library. Ipamorelin (entry 0009), revision 1.0, 2 November 2026. peptidarium.com/library/ipamorelin

08

Revision history

RevDateChangeBy
1.02 Nov 2026Entry created.[Scientific editor]

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