Dr. Pep

Peptides · Selective ghrelin-receptor agonist (GH secretagogue)

Ipamorelin: what the studies show

Every line below comes from a study, label or regulator record, checked by two models, with the source linked. Information, not medical advice. For adults 18+.

What it is

  • Ipamorelin is a five-amino-acid synthetic peptide that acts on the ghrelin receptor and makes the pituitary release growth hormone (a 'growth hormone secretagogue'). Its early code name was NNC 26-0161. It has been tested for post-surgery bowel paralysis (postoperative ileus).[1][2][3][4]
  • It is not an approved drug anywhere in the records here. It is sold online as a 'research peptide' and is compounded.[5][6]

Bottom line

  • The only human data are a 1999 dose-escalation study in 40 healthy men that showed it releases growth hormone, and a small 2014 trial in bowel surgery patients that found no benefit. There is no human evidence for the muscle, anti-aging or fat-loss claims it is marketed for.[7][4]

What the human studies found

  • Pharmacokinetics and growth hormone response (1999, 8 healthy men at each of 5 IV doses from 4.21 to 140.45 nmol/kg over 15 minutes): drug levels rose in proportion to dose, with a terminal half-life of about 2 hours. A single burst of growth hormone followed each dose, peaking at about 0.67 hours and falling back to negligible levels. This shows it releases growth hormone briefly; it did not test any health benefit.[7]
  • Postoperative ileus, phase 2 proof-of-concept RCT (114 analysed adults after bowel resection, double-blind): ipamorelin 0.03 mg/kg IV twice daily for up to 7 days versus placebo. Median time to first tolerated meal was 25.3 hours on ipamorelin and 32.6 hours on placebo, which was not a significant difference (p=0.15). Any adverse event occurred in 87.5% on ipamorelin and 94.8% on placebo. The authors called it well tolerated, found no significant differences in key or secondary efficacy results, and noted the study was small with mixed surgeries.[4][8]
  • A larger phase 2 dose-finding trial in bowel resection patients (320 planned; 0.03 mg/kg twice daily, 0.06 mg/kg twice or three times daily, versus placebo) is registered as completed. No results from it are in the records we hold.[9]

Known risks and side effects

  • The ileus trial reported no excess adverse events on ipamorelin (87.5% versus 94.8% on placebo) over up to 7 days of IV dosing in hospital patients. It did not test long-term or injected-at-home use.[4]
  • FDA states that a published study found serious adverse events, including death, when ipamorelin was given IV to improve gastric motility. It also says compounded ipamorelin may carry immunogenicity risk from peptide aggregation or impurities, and that it lacks safety information for other injection routes. The abstract of the ileus trial here does not report these details, so they could not be matched to a specific result.[6][4]

Legal status

  • FDA's Pharmacy Compounding Advisory Committee met on 2024-10-29 on ipamorelin. On the question of placing ipamorelin free base on the section 503A bulks list, the record shows zero yes votes, 12 no votes and 1 abstention. FDA had proposed not including it.[10]
  • FDA's category 2 list (page retrieved 2026-10-09) puts ipamorelin acetate among bulk substances that may present significant safety risks for compounding.[6]
  • An FDA warning letter dated 2026-08-24 to NuScience Peptides named a 'Tesamorelin Ipamorelin Blend' sold as a research peptide among unapproved new drugs.[5]

Sources

  1. [1] Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats.
  2. [2] Pharmacokinetic evaluation of ipamorelin and other peptidyl growth hormone secretagogues with emphasis on nasal absorption.
  3. [3] Efficacy of ipamorelin, a novel ghrelin mimetic, in a rodent model of postoperative ileus.
  4. [4] Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients.
  5. [5] FDA: Warning Letter, NuScience Peptides LLC (2026-08-24), tesamorelin, ipamorelin, PT-141, retatrutide, survodutide, mazdutide
  6. [6] FDA: Certain bulk drug substances for use in compounding that may present significant safety risks (503A/503B category 2)
  7. [7] Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers.
  8. [8] Safety and Efficacy of Ipamorelin for Management of Post-Operative Ileus
  9. [9] Safety and Efficacy of Ipamorelin Compared to Placebo for the Recovery of Gastrointestinal Function
  10. [10] FDA: PCAC Topic 3 transcript, ipamorelin (2024-10-29)