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Ipamorelin Efficacy in Black and African Ancestry Patients: Documented Gaps and Pharmacogenomic Considerations

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At a glance

  • FDA status / Not approved for any indication; listed in FDA category 2 for outsourcing-facility compounding [2][4]
  • Published phase 2 result / Median time to first tolerated solid meal 25.3 hours on ipamorelin vs 32.6 hours on placebo (p=0.15, not significant) [1]
  • Human dosing studied / Intravenous only: 0.03 mg/kg twice daily in the ileus trial; single 15-minute infusions in volunteers [1][3]
  • Subcutaneous data / FDA found no human PK, safety or efficacy data [2]
  • GHSR rs2922126 / A allele frequency 0.102 in African-group and 0.345 in European-group allele observations (gnomAD v4) [5]
  • Sports status / Prohibited at all times by WADA, class S2.2.4 [6]

What human data exists?

Two human studies provide the clinical and pharmacokinetic data below [1][3]. The larger was a phase 2 trial in adults having bowel resection: 117 enrolled, 114 analyzed, ipamorelin 0.03 mg/kg intravenously twice daily from day 1 to 7 or discharge [1]. Median time to first tolerated solid meal was 25.3 hours on ipamorelin vs 32.6 hours on placebo (p=0.15), and any treatment-emergent adverse event occurred in 87.5% vs 94.8% [1]. The other gave healthy male volunteers single 15-minute intravenous infusions from 4.21 to 140.45 nmol/kg; terminal half-life was about 2 hours, clearance 0.078 L/h/kg, and growth hormone peaked about 0.67 hours after infusion [3]. Both used intravenous ipamorelin; FDA found no human pharmacokinetic, safety or efficacy data for subcutaneous ipamorelin [2].

Do they report results by race or ancestry?

Not in the published abstracts. The ileus abstract describes the groups as balanced on demographic and disease characteristics but gives no efficacy or safety results by race or ancestry [1]. The volunteer study enrolled eight healthy men per dose level, with no ancestry breakdown in its abstract [3].

GHSR variation

Ipamorelin releases growth hormone by acting at the ghrelin/GH-secretagogue receptor, not the GHRH receptor [8]. rs2922126 is catalogued as a GHSR variant about 2 kb upstream of the gene [5]. In gnomAD v4, the A allele frequency was 0.102 among African-group allele observations and 0.345 among European-group allele observations [5]. These frequencies do not establish an ipamorelin response difference.

What the FDA record says to watch for

In the ileus trial, low potassium occurred in 12.5% vs 3.4% on placebo, insomnia in 10.7% vs 5.2%, high blood sugar at discharge in 14.3% vs 8.6%, and serious adverse events in 17.9% vs 15.5% [2][1]. Two ipamorelin-treated patients died of surgical complications; FDA said it is unclear whether the deaths were related to the drug but that they raise safety concerns [2]. Because ipamorelin stimulates the GH and IGF-1 axis, FDA says it may carry risks listed on approved growth hormone labels, including neoplasm, glucose intolerance and diabetes, intracranial hypertension, fluid retention, hypothyroidism and pancreatitis, and possibly QT prolongation like macimorelin [2]. FDA lists ipamorelin acetate in category 2 for outsourcing-facility compounding, added September 29, 2023 and still listed on the page dated April 22, 2026 [4]. In October 2024 the Pharmacy Compounding Advisory Committee voted 0 yes, 12 no, 1 abstention on the acetate [9]. WADA prohibits ipamorelin at all times in class S2.2.4 [6].

Bottom line

No human data show whether ipamorelin works differently by ancestry. The only published efficacy trial missed its main endpoint, the peptide is not FDA-approved, and FDA found no human data for subcutaneous use [1][2].

Frequently asked questions

Does ipamorelin have a dose for Black or African ancestry patients?
No FDA-approved dose exists for anyone. Human studies used intravenous ipamorelin only: 0.03 mg/kg twice daily in a postoperative ileus trial, and single 15-minute infusions of 4.21 to 140.45 nmol/kg in healthy volunteers [1][3]. These are study doses, not recommended doses. FDA found no human PK, safety or efficacy data for subcutaneous ipamorelin [2].
Is the GHSR variant rs2922126 more common in African ancestry populations?
Less common in gnomAD v4: the A allele frequency was 0.102 among African-group allele observations and 0.345 among European-group allele observations [5]. Allele frequency alone does not show how a receptor variant changes the response to a drug.
Is ipamorelin FDA-approved, and can it be compounded?
It is not FDA-approved for any indication [2]. FDA lists ipamorelin acetate in category 2, bulk substances that may present significant safety risks for compounding by outsourcing facilities [4]. FDA's advisory committee voted 0 yes, 12 no, 1 abstention on adding the acetate to the pharmacy bulks list in October 2024 [9].
What side effects were seen in the ipamorelin trial?
In the ileus trial: low potassium 12.5% vs 3.4% on placebo, insomnia 10.7% vs 5.2%, high blood sugar at discharge 14.3% vs 8.6%, serious adverse events 17.9% vs 15.5%, and two ipamorelin-treated patients who died of surgical complications, with the relationship to the drug described as unclear [2][1].

References

  1. Beck DE, Sweeney WB, McCarter MD, Ipamorelin 201 Study Group. 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):1527-34. Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients
  2. U.S. Food and Drug Administration. U.S. Food and Drug Administration
  3. Gobburu JV, Agersø H, Jusko WJ, Ynddal L. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharm Res. 1999;16(9):1412-6. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers
  4. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks | FDA. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks | FDA
  5. rs2922126 RefSNP Report - dbSNP - NCBI. rs2922126 RefSNP Report - dbSNP - NCBI
  6. World Anti-Doping Agency. World Anti-Doping Agency
  7. Collection of Race and Ethnicity Data in Clinical Trials | FDA. Collection of Race and Ethnicity Data in Clinical Trials | FDA
  8. Raun K, Hansen BS, Johansen NL, Thøgersen H, Madsen K, Ankersen M, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552-61. Ipamorelin, the first selective growth hormone secretagogue
  9. U.S. Food and Drug Administration. U.S. Food and Drug Administration
Evidence overview for Ipamorelin Efficacy in Black and African Ancestry Patients: Documented Gaps and Pharmacogenomic Considerations