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Ipamorelin

Growth hormone secretagogue (ghrelin receptor agonist)

Status

Not approved

Never approved; development for postoperative ileus ended after a negative phase 2 trial, FDA's compounding advisory committee voted 12-0 (one abstention) in October 2024 against adding it to the 503A bulks list, and it remains on FDA's 503B Category 2 list of substances raising significant safety risks.

Evidence

Preliminary

Human data are limited to a pharmacokinetic study in healthy men and one small phase 2 trial that missed its main endpoint.

In sport

WADAProhibited (WADA)

Ipamorelin is a small synthetic peptide that mimics the hunger hormone ghrelin to trigger growth hormone release. Developed by Novo Nordisk and later tested for bowel recovery after surgery, it was never approved and is sold online as a research chemical.

Structure

5 residues

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D-form (mirror image), shown in lower case

Sequence as text
H-Aib-H-D-2Nal-D-Phe-K-NH2

What it is used for

  • Postoperative ileus (slow return of bowel function) after bowel surgery (studied)
  • Growth hormone deficiency, the use proposed for compounding (claimed, unproven)
  • Muscle gain, fat loss, sleep or anti-ageing (claimed, unproven)

How it works

Ipamorelin activates the growth hormone secretagogue receptor (the ghrelin receptor) in the pituitary and hypothalamus, producing a single short burst of growth hormone. In animal studies it was notably selective: unlike GHRP-6 and GHRP-2, it did not raise ACTH or cortisol even at doses far above those needed for growth hormone release, and it did not change other pituitary hormones. Ghrelin receptor activation also stimulates gut movement, which is why it was tested for postoperative ileus.

How strong the evidence is

PreliminarySmall human studies, pilots or observational data.

Raun and colleagues (1998) described its potency and selectivity in rat and pig studies. In healthy men given intravenous infusions, it produced a single growth hormone peak about 40 minutes later and had a terminal half-life of about 2 hours (Gobburu 1999). A phase 2 randomized trial in 117 bowel resection patients found no significant difference from placebo in time to first tolerated meal (25.3 versus 32.6 hours, p = 0.15), and development was discontinued (Beck 2014). FDA's 2024 review found no data supporting effectiveness for growth hormone deficiency.

Risks and side effects

  • Two deaths from surgical complications occurred in ipamorelin-treated patients in the ileus trial; FDA could not rule out a link
  • Higher rates of low potassium and high blood sugar were reported with ipamorelin in that trial
  • Immunogenicity and impurity risks from its unnatural amino acids flagged by FDA
  • Research-chemical products are unregulated and of uncertain purity
  • Prohibited in sport at all times (WADA S2)

Regulatory status

No regulator has approved this peptide for any use.

Status by country

JurisdictionStatusSource
USUnited StatesNo authorised medicineSource 5
EUEuropean UnionNo authorised medicineSource 9
UKUnited KingdomNo authorised medicineSource 10
AUAustraliaNo authorised medicineSource 11
CACanadaNo authorised medicineSource 12
Whether a medicine containing it is authorised, checked in each regulator’s records on Oct 1, 2026.

Status of every peptide by country

Timeline

  1. 2026

    1. ResearchReview of 565 studies finds little human evidence for popular injectable peptides
    2. RegulatoryFDA warning letters reject 'research use only' labels on online GLP-1 peptide sales
    3. SafetyHealth Canada warns against injecting peptides bought online and names seized products

Articles about Ipamorelin

Sources

  1. 01Ipamorelin (CID 9831659)(opens the source in a new tab) PubChem, NCBI, 2026
  2. 02Ipamorelin, the first selective growth hormone secretagogue(opens the source in a new tab) Eur J Endocrinol, 1998
  3. 03Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers(opens the source in a new tab) Pharm Res, 1999
  4. 04Prospective, randomized, controlled, proof-of-concept study of the ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients(opens the source in a new tab) Int J Colorectal Dis, 2014
  5. 05FDA Briefing Document: ipamorelin, Pharmacy Compounding Advisory Committee, October 29, 2024(opens the source in a new tab) U.S. Food and Drug Administration, 2024
  6. 06Pharmacy Compounding Advisory Committee meeting, October 29, 2024: minutes(opens the source in a new tab) U.S. Food and Drug Administration, 2024
  7. 07Safety Risks Associated with Certain Bulk Drug Substances Nominated for Use in Compounding (Category 2)(opens the source in a new tab) U.S. Food and Drug Administration, 2026
  8. 08World Anti-Doping Code International Standard: Prohibited List 2026(opens the source in a new tab) World Anti-Doping Agency, 2025
  9. 09Find medicine: centrally authorised medicines(opens the source in a new tab) European Medicines Agency, 2026
  10. 10MHRA Products: active substances beginning with I(opens the source in a new tab) Medicines and Healthcare products Regulatory Agency, 2026
  11. 11Australian Register of Therapeutic Goods (ARTG)(opens the source in a new tab) Therapeutic Goods Administration
  12. 12Think twice before injecting peptides bought online: unauthorized products can seriously harm you(opens the source in a new tab) Health Canada, 2026
  1. Not approvedCJC-1295Long-acting GHRH analogue (research peptide)30 WADA banned
  2. Not approvedGHRP-6Growth hormone secretagogue (ghrelin receptor agonist)6 WADA banned
  3. WithdrawnSermorelinGrowth hormone-releasing hormone (GHRH) analogue29 WADA banned
  4. ApprovedTesamorelinGrowth hormone-releasing factor (GHRF) analogue44 WADA banned

Educational information, not medical advice. Talk to a licensed clinician before starting, stopping or changing any medicine.