What it is
Ipamorelin is a synthetic peptide of five amino acids that makes the pituitary gland release growth hormone.
It is worth pausing on how short that is. Sermorelin is 29 amino acids and is a fragment of a real human hormone; tesamorelin is 44 and is an engineered version of one. Ipamorelin is five residues long and is not a fragment of anything in the body. It is a small designed molecule that happens to fit a receptor.
The receptor it fits is the growth hormone secretagogue receptor — the one the natural hormone ghrelin uses. That is a different door into the same system from the one sermorelin uses, and it is why ipamorelin is grouped with the ghrelin mimetics rather than with the releasing-hormone analogues. The original compound at that receptor was GHRP-6, which ipamorelin was designed to improve on by leaving cortisol and prolactin largely alone.
What it is said to be good for
Almost everything written about ipamorelin for a consumer audience concerns muscle, recovery, fat loss and ageing.
Almost everything in its actual development record concerns the bowel.
What the research shows
This is the shortest evidence section in the library so far, because there is very little to report, and that is itself the finding.
The published literature is thin. PubMed indexed 50 records for ipamorelin on 2026-09-07, of which 24 are tagged as human research and 2 are randomized controlled trials. For comparison, the same search method returns 445 records for sermorelin and 253 for MOTS-c.
The registered human programme is two trials, and it stopped. ClinicalTrials.gov lists three interventional studies naming ipamorelin. Two of them are the drug programme, both sponsored by Helsinn Therapeutics:
| Trial | Phase | Participants | Completed | What it tested | Results posted |
|---|---|---|---|---|---|
| NCT00672074 | 2 | 117 | December 2009 | Recovery of gastrointestinal function after bowel resection | No |
| NCT01280344 | 2 | 320 | June 2013 | Recovery of gastrointestinal function | No |
Nothing follows them. No Phase 3, no approval anywhere, and no registered study of the compound in the decade since.
The published trial did not beat placebo. The smaller of the two was published by Beck and colleagues in the International Journal of Colorectal Disease in December 2014. In 117 patients undergoing bowel resection, the median time from first dose to tolerating a standard solid meal was 25.3 hours on ipamorelin against 32.6 hours on placebo — a gap that did not reach statistical significance (p = 0.15). The authors' own conclusion was that the drug was well tolerated and that there were no significant differences between ipamorelin and placebo in the key and secondary efficacy analyses.
Seven hours sounds like something. A p-value of 0.15 in 117 patients means the study could not distinguish that gap from chance, and the trial was designed as proof of concept precisely because that question was open. The larger 320-patient study that followed has no posted results, so the public record ends there.
What is reliably established is narrower and much less exciting: ipamorelin causes growth hormone to be released. A dose-ranging study in healthy male volunteers, published in Pharmaceutical Research in September 1999, characterised it as a single episode of release peaking around 0.67 hours and declining to negligible levels, with a terminal half-life of about 2 hours. That is a real, measured, reproducible pharmacological effect.
It is not a benefit. A burst of growth hormone is a change in a blood measurement. Whether that change produces anything a person would notice — more muscle, better recovery, slower ageing — is a separate question, and it is the question no registered ipamorelin trial has ever asked.
Where it stands
Approved as a medicine: nowhere, and no application exists to point at.
Development status: two Phase 2 trials completed, the last in June 2013, neither with results posted, nothing since.
Regulatory attention: ipamorelin has appeared by name in FDA warning letters to sellers of research peptides, as part of the product lines those letters address.
Available as: a research chemical and through compounding pharmacies.
Related entries in this library: sermorelin and the approved growth-hormone-releasing analogue tesamorelin reach growth hormone through the releasing-hormone receptor rather than the ghrelin receptor, and both have far larger human records — one as a discontinued approved drug, one as a current approved drug for a narrow use.
Last checked
2026-09-07. The ClinicalTrials.gov records for NCT00672074 and NCT01280344 were read through the registry API on that date; the PubMed counts were run the same day; the trial and pharmacology findings are quoted from the published abstracts named above.