What does ipamorelin do according to research?

Preclinical work in rats and swine reports that it binds the ghrelin receptor and prompts pituitary release of growth hormone, selectively — without the rises in ACTH and cortisol seen with earlier secretagogues. That selectivity is the property it was designed for.

Has ipamorelin been tested in humans?

Yes, which is rare for compounds in this catalogue. A phase 2 randomised, double-blind, placebo-controlled trial in 117 bowel-resection patients tested it for postoperative ileus. It was published in 2014.

What was the result of the ipamorelin human trial?

Negative on efficacy. Time to tolerating a solid meal was shorter than placebo but not significantly so, and secondary efficacy analyses showed no significant difference either. On tolerability the result was reassuring: adverse events were slightly less frequent than on placebo.

Is ipamorelin selective?

That is the claim the original 1998 characterisation makes, in rats and swine — growth hormone release without accompanying ACTH and cortisol elevation. It has not been independently re-examined in humans, so the selectivity is preclinical evidence rather than established human pharmacology.

Is ipamorelin an approved medicine?

No. Development did not proceed past the phase 2 study described above and it holds no marketing authorisation anywhere. It is supplied here as a laboratory reagent for research use only.

Research guides

Ipamorelin: what the research says

A selective growth hormone secretagogue with a completed, published human trial. It missed its primary endpoint, and that is the most useful result it has.

Available in the catalogue

Supplied as research material. Sizes and pricing are on the product page. Availability is not a statement about what a compound does.

IPAMORELIN
Growth Hormone

Ipamorelin is unusual in this catalogue in two ways. It was developed inside a pharmaceutical company, and it reached a completed randomised controlled trial in humans whose results were published. The trial did not meet its endpoint. Both halves of that sentence belong in any honest summary of the compound.

What the molecule is

A synthetic pentapeptide developed at Novo Nordisk as a growth hormone secretagogue, and also designated NNC 26-0161. It binds the ghrelin receptor and prompts the pituitary to release its own growth hormone, rather than supplying growth hormone directly — the distinction that defines the secretagogue class.

Selectivity is the design goal

Earlier compounds in the class released growth hormone but also raised adrenocorticotropic hormone and cortisol, which limited their usefulness as research tools because any observed effect could be attributable to either axis. The original 1998 characterisation reported that ipamorelin released growth hormone without those accompanying rises. That selectivity, rather than potency, is what the molecule was built for and is the reason it remains a reference compound in the class.

The trial, and why a null result is worth publishing

A phase 2 randomised, double-blind, placebo-controlled multicentre study enrolled 117 adults undergoing bowel resection, testing whether ghrelin-receptor stimulation would shorten postoperative ileus — the temporary shutdown of gut motility that follows abdominal surgery. The rationale was sound: ghrelin-receptor agonists have promotility effects in the gastrointestinal tract.

Median time to tolerating a solid meal was shorter in the ipamorelin group than in the placebo group, but the difference did not reach statistical significance, and no significant difference was found on the secondary efficacy analyses either. The compound was well tolerated, with a slightly lower overall rate of treatment-emergent adverse events than placebo.

That is a negative result on efficacy and a reassuring one on tolerability, in the same study, in humans. It is more informative than a shelf of positive rodent papers, and it is almost never mentioned in descriptions of this compound.

What studies reported

Each entry states what a study examined and the model it used. Nothing below describes an outcome for a person.

Everything below is drawn from published research, and each entry names the model the study used. Approval status varies by compound and by country, and nothing described here is supplied as a medicine or for use in a person.

Raun et al. (1998)European Journal of Endocrinology · 139(5):552–61
Original characterisation of the compound's growth-hormone-releasing potency and its selectivity relative to other secretagogues, reporting release without accompanying rises in ACTH and cortisol.
in vitro and in vivo, rat and swine Source

Adverse and null findings reported

Harms, tolerability observations, and trials that did not meet their endpoint. A negative result is a finding and is listed here rather than omitted.

Beck et al. (2014)International Journal of Colorectal Disease · 29(12):1527–34
Tested the compound against placebo for management of postoperative ileus after bowel resection. It was well tolerated, with treatment-emergent adverse events slightly less frequent than on placebo, but showed no significant difference from placebo on the primary endpoint of time to tolerating a solid meal, or on secondary efficacy analyses.
human, phase 2 randomised double-blind placebo-controlled, 117 patients Source

What the research does not establish

An absence cannot be cited, so these are stated plainly. They are the part of the picture that silence would otherwise hide.

The only published randomised human trial tested one indication, postoperative ileus, over a short inpatient period. Nothing about longer-term administration in humans has been published.
No published human trial has measured growth hormone or IGF-1 outcomes as its primary endpoint. The growth-hormone-releasing activity that defines the compound is characterised in rats and swine.
The reported selectivity over ACTH and cortisol comes from the original preclinical characterisation and has not been re-examined independently in humans.
Development did not continue to phase 3 for the indication studied, and the compound has no marketing authorisation in any jurisdiction.
Effects of sustained secretagogue stimulation on the growth hormone axis over months or years are not addressed by any published study of this compound.

Common questions

What does ipamorelin do according to research?: Preclinical work in rats and swine reports that it binds the ghrelin receptor and prompts pituitary release of growth hormone, selectively — without the rises in ACTH and cortisol seen with earlier secretagogues. That selectivity is the property it was designed for.
Has ipamorelin been tested in humans?: Yes, which is rare for compounds in this catalogue. A phase 2 randomised, double-blind, placebo-controlled trial in 117 bowel-resection patients tested it for postoperative ileus. It was published in 2014.
What was the result of the ipamorelin human trial?: Negative on efficacy. Time to tolerating a solid meal was shorter than placebo but not significantly so, and secondary efficacy analyses showed no significant difference either. On tolerability the result was reassuring: adverse events were slightly less frequent than on placebo.
Is ipamorelin selective?: That is the claim the original 1998 characterisation makes, in rats and swine — growth hormone release without accompanying ACTH and cortisol elevation. It has not been independently re-examined in humans, so the selectivity is preclinical evidence rather than established human pharmacology.
Is ipamorelin an approved medicine?: No. Development did not proceed past the phase 2 study described above and it holds no marketing authorisation anywhere. It is supplied here as a laboratory reagent for research use only.

Compounds covered

The reference page for each compound this article discusses.

Ipamorelin

CJC-1295 (Mod GRF 1-29): what the research says
The best-known CJC-1295 human trial studied the DAC form, not the no-DAC form sold as Mod GRF 1-29. Why the two have very different pharmacokinetics.
Semax: what the research says
An ACTH(4-10) analogue registered as a medicine in Russia and unknown to Western regulators. What the BDNF work reported, and why the English record looks thin.
Peptide shelf life and stability
How long lyophilised and reconstituted peptides keep, and the four things that shorten it: temperature, moisture, light and oxidation. Storage figures included.

About this article

Everything reported here comes from published research, and each finding names the model the study used — cell culture, rat, or human. Findings in one model do not transfer to another, most of the work described is preclinical, and none of it is a claim that a compound is safe or effective for any purpose. Nothing on this page describes doses, routes of administration, or use in a person.

Approval status varies by compound and by country. A few of the substances described are the active ingredient of medicines authorised in the EU; most have no marketing authorisation anywhere and have never been assessed by a regulator. Neither is supplied as a medicine here. All material supplied by ASSAY is sold for in-vitro laboratory research only, and is not a drug, food, cosmetic or medical device, and not for human or veterinary use.

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