Research guide / Ipamorelin
What is Ipamorelin? A Complete Research Guide.
Updated August 2026 · 10 minute read
Ipamorelin is a pentapeptide described in the literature as the first selective growth hormone secretagogue. This guide separates the published human and preclinical studies from what regulators have actually said.
01 / Overview
What is Ipamorelin?
Ipamorelin is a synthetic pentapeptide (five amino acids) that stimulates growth hormone release from the pituitary. It was characterised in 1998 by researchers at Novo Nordisk as the first growth hormone secretagogue with selectivity comparable to natural GHRH — meaning it raised growth hormone without significantly raising other pituitary hormones such as ACTH, cortisol, or prolactin in the studied models.[1]
Its only registered clinical development programme tested intravenous ipamorelin for postoperative ileus — delayed bowel recovery after surgery — not for growth hormone deficiency, body composition, or any wellness indication. That Phase 2 programme did not demonstrate efficacy on its primary endpoint and was discontinued.[4], [5]
Unlike approved medicines, ipamorelin never advanced to Phase 3. Its published human evidence consists of small pharmacology studies and one Phase 2 trial for an unrelated indication. That limited base shapes everything below.
02 / Mechanism
How does ipamorelin work?
Ipamorelin acts at the growth hormone secretagogue receptor (GHS-R, the ghrelin receptor) on pituitary cells, triggering release of stored growth hormone. Its distinguishing feature in the literature is selectivity: in the original characterisation studies it stimulated growth hormone release without the ACTH and prolactin elevations seen with earlier secretagogues such as GHRP-6.[1], [3]
| Aspect | What research reports | Research relevance |
|---|---|---|
| GHS-R (ghrelin receptor) | Ipamorelin stimulates growth hormone release via the growth hormone secretagogue receptor on pituitary cells. | A different receptor pathway from GHRH analogues such as CJC-1295. |
| Selectivity | Original studies report GH release without significant ACTH, cortisol, or prolactin elevation at effective doses. | The feature that distinguished ipamorelin from earlier secretagogues. |
| Short half-life | Human pharmacokinetic work describes rapid clearance after administration. | Why studied dosing was frequent; long-acting formulations were never developed. |
Selectivity findings come from the original preclinical and early human pharmacology work. They describe acute hormonal responses in controlled settings; they do not establish that long-term or repeated use would remain free of other hormonal effects.
03 / Published evidence
Peer-reviewed findings
The 1998 characterisation study in the European Journal of Endocrinology reported that ipamorelin potently and dose-dependently released growth hormone in vitro and in vivo, with a selectivity profile comparable to GHRH — no significant effect on ACTH, cortisol, prolactin, FSH, LH, or TSH at effective doses in the studied systems.[1]
A 1999 pharmacokinetic-pharmacodynamic study in human volunteers modelled the relationship between ipamorelin dose and growth hormone response, establishing dose-dependent GH release in people. The study measured hormone levels, not clinical outcomes.[3]
Preclinical work in rats reported that ipamorelin induced longitudinal bone growth and influenced body composition — animal findings that generated hypotheses but cannot be extrapolated to human benefit.[2]
The largest human trial was a Phase 2 randomised controlled study of intravenous ipamorelin for postoperative ileus, published in BMC Gastroenterology in 2014. Ipamorelin did not significantly improve the primary endpoint versus placebo, and development for that indication ended. This remains the most rigorous human trial of the compound.[4]
04 / Evidence landscape
How the evidence is structured
Ipamorelin's registered clinical programme targeted postoperative ileus, not growth hormone or body-composition indications. The table below maps the main categories of published evidence.
| Category | Example | Scale | What it can show |
|---|---|---|---|
| Characterisation study | Raun et al., 1998 | In vitro and animal models | Potent, selective GH release in studied systems |
| Human PK/PD study | Gobburu et al., 1999 | Small volunteer study | Dose-dependent GH response in people; no clinical outcomes |
| Phase 2 RCT (postoperative ileus) | Beck et al., 2014 | Randomised, placebo-controlled | No significant benefit on the primary endpoint; programme discontinued |
This mapping reflects the published records reviewed for this August 2026 update. The absence of any trial for the indications ipamorelin is popularly discussed for is itself a finding: claims beyond the evidence should be treated with caution.[1], [3], [4]
Afiya Labs lists an ipamorelin reference material for laboratory research. The catalogue entry is not a medicine listing and is not presented as suitable for human use.
05 / Safety evidence
What safety evidence exists?
In the Phase 2 postoperative ileus trial, intravenous ipamorelin was reported as generally well tolerated over the short treatment period studied. That trial was not designed or powered to detect uncommon or long-term adverse effects, and it used intravenous dosing in a surgical setting.[4]
The U.S. FDA has identified potential significant safety risks for ipamorelin and placed it in Category 2 of its interim compounding policy — the category for bulk substances that may present significant safety risks. Category placement is a regulatory risk signal, not a full safety assessment.[6]
There are no large, long-term human safety trials of subcutaneous ipamorelin for any indication. Anyone reading claims about its use should weigh them against that absence of controlled human data.
06 / Regulators
Status in the US, Europe, and UAE
United States
Ipamorelin is not an FDA-approved drug. Under the FDA's interim compounding policy, ipamorelin is listed in Category 2 — bulk drug substances that may present significant safety risks in compounding. This category concerns pharmacy compounding and is not a marketing authorisation.[6]
European Union
Ipamorelin is not authorised as a medicine in the EU and has no completed pharmaceutical development programme in any jurisdiction.
United Arab Emirates
The Emirates Drug Establishment maintains the UAE's public registered medical product directory. We did not rely on a directory search to infer approval, non-approval, legality, availability, or permission for use of any specific product; those questions require confirmation from the EDE. Approved medicines in the UAE are dispensed through licensed channels.[7]
07 / Quick answers
Frequently asked questions
Is ipamorelin an approved medicine?
No. Ipamorelin is not approved as a drug in the US, authorised as a medicine in the EU, or approved anywhere else. Its only registered clinical programme — for postoperative ileus — ended after Phase 2.
What does 'selective' mean for ipamorelin?
In the original studies, ipamorelin raised growth hormone without significantly raising ACTH, cortisol, or prolactin at effective doses — unlike some earlier growth hormone secretagogues. This is an acute pharmacology finding, not a long-term safety guarantee.
What does the research actually show?
Small human studies show ipamorelin raises growth hormone in a dose-dependent way. The only randomised controlled trial tested it for postoperative ileus and found no significant benefit on the primary endpoint. No trial has tested it for fat loss, muscle gain, or recovery.
Why is ipamorelin on the FDA's Category 2 list?
The FDA identified potential significant safety risks for ipamorelin as a bulk compounding substance and placed it in Category 2 of its interim compounding policy. This is a compounding-policy decision, not a full drug review.
Is ipamorelin the same as ghrelin?
No. Ghrelin is a natural hormone that also stimulates appetite. Ipamorelin is a synthetic pentapeptide that acts at the same receptor family but was characterised as selective for growth hormone release without ghrelin's broader effects in the studied models.
What does the UAE directory show?
It is a public register of medical products. This guide does not turn a directory search result — or the absence of one — into a claim about approval, legality, or permitted use. The EDE is the appropriate authority for a current determination.
08 / Sources
References and original records
- 1Ipamorelin, the first selective growth hormone secretagogue. European Journal of Endocrinology (Raun, Hansen & Johansen). 1998 · DOI 10.1530/eje.0.1390552 · Original characterisation study.
- 2Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats. Growth Hormone & IGF Research (Johansen et al.). 1999 · Preclinical study.
- 3Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharmaceutical Research (Gobburu et al.). 1999 · DOI 10.1023/A:1018955126402 · Human pharmacokinetic study.
- 4Randomized controlled trial of ipamorelin for postoperative ileus management. BMC Gastroenterology (Beck et al.). 2014 · DOI 10.1186/1471-230X-14-20 · Phase 2 randomised controlled trial.
- 5Study record: ipamorelin in postoperative ileus (NCT00672074). ClinicalTrials.gov. Official trial registry record.
- 6Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (Category 2). U.S. Food and Drug Administration. Official regulatory list · includes ipamorelin.
- 7Registered medical product directory. UAE Emirates Drug Establishment. Official public directory · checked August 2026.