Ipamorelin
Clinical reviewer: Jacob Moore, MD · Last checked September 22, 2026
What is ipamorelin?
Ipamorelin is a synthetic pentapeptide that stimulates the pituitary to release growth hormone, acting as a relatively selective agonist of the GHSR-1a receptor. It has a human pharmacokinetic study and a negative 2014 postoperative trial behind it, is not FDA-approved, and carries an active FDA Category 2 safety listing under the 503B pathway even though its 503A nomination was withdrawn.
What does research show about ipamorelin?
A 1998 study by its developer describes ipamorelin as a pentapeptide with high growth-hormone-releasing potency in vitro and in vivo, acting through a GHRP-like receptor without raising ACTH or cortisol above levels seen with GHRH [1]. A 1999 dose-escalation study infused eight healthy men at each of five dose levels; the peptide's terminal half-life was about 2 hours, with growth hormone peaking at about 0.67 hours after dosing [2]. A 2014 phase 2 trial gave twice-daily infusions to 117 enrolled surgical patients; median time to first tolerated meal was 25.3 hours with ipamorelin versus 32.6 hours with placebo, a difference the authors said was not statistically significant [3].
Is ipamorelin FDA-approved or legal to compound?
No. Ipamorelin acetate is not FDA-approved. FDA's Category 2 list, current as of April 22, 2026, records a study that identified serious adverse events including death when ipamorelin was administered intravenously for improving gastric motility, and states FDA lacks sufficient safety information about other injectable routes [4]. Its section 503A compounding nomination was withdrawn, while the separate 503B Category 2 listing for ipamorelin acetate remains active [4]. Ipamorelin belongs to the class of growth hormone secretagogues, each evaluated individually for compounding eligibility.
Related terms
Sources
- Raun K et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol, 1998.
- Gobburu JV et al. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharm Res, 1999.
- Beck DE et al. 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.
- FDA — Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (Category 2), current as of April 22, 2026
This entry is for education and is not medical advice. Talk with a licensed clinician about your own situation before starting, stopping, or changing any treatment.
