Prepared by: Research Desk. Sources are linked for verification.

Ipamorelin is a synthetic pentapeptide (five amino acids) first described in 1998 as a growth hormone secretagogue. A secretagogue is a compound that prompts the pituitary gland to release growth hormone (GH). The original publication called it "the first selective growth hormone secretagogue." In the animal experiments it reported, ipamorelin raised GH without the rise in stress hormones seen with earlier compounds of its class [1]. It acts at the ghrelin receptor, which is why later papers describe it as a ghrelin mimetic [2].

This entry follows the standard Peptide Infinity template: status, identity, mechanism, key evidence, regulatory notes and sources. It reports what published studies measured. It does not describe use in humans.

Status at a glance

For what each status badge means and how it is verified, see Peptide FDA status explained.

Identity and place in the peptide family

Ipamorelin belongs to a family of small synthetic peptides developed to stimulate GH release through a route separate from growth hormone-releasing hormone (GHRH). The GHRH route is the one used by sermorelin and tesamorelin. Ipamorelin instead acts on the receptor later identified as the target of ghrelin, a hormone produced mainly in the stomach [3].

Raun and colleagues reported that ipamorelin was derived from an earlier growth hormone-releasing peptide. Its sequence contains non-standard amino acids, including D-isomers and the synthetic residue aminoisobutyric acid (Aib) [1]. Non-standard residues like these are a common chemist's tool for making a short peptide more resistant to enzymatic breakdown. For background on what makes a five-residue chain a "peptide" at all, see What are peptides?. The peptide glossary defines secretagogue, agonist and related terms used below.

Mechanism: the ghrelin receptor

Ghrelin's receptor, the growth hormone secretagogue receptor (GHSR), is expressed in the pituitary and hypothalamus and in other tissues [3]. A 2018 review in Cell Metabolism described the ghrelin system as a broad "homeostatic" signal, linked to GH release, appetite, energy balance and gastrointestinal motility [3]. A 2021 review surveyed efforts to develop ghrelin-based compounds for metabolic conditions and noted how many physiological systems the receptor touches [4].

That breadth explains two threads in the ipamorelin literature. The first concerns GH release and how selective it is. The second concerns gut motility, because ghrelin receptor activation is associated with gastric emptying and intestinal transit [3]. Other reviews have examined the ghrelin system in Alzheimer's disease [5] and in mental disorders [6]. Those papers concern the receptor system generally, not ipamorelin specifically.

Discovery: the 1998 selectivity study

The founding paper, published in the European Journal of Endocrinology, combined cell experiments with animal studies [1].

What was measured. In cultured rat pituitary cells, the authors reported that ipamorelin released GH with a potency and efficacy similar to the earlier reference compound GHRP-6 [1]. In swine, they examined GH release together with other pituitary and adrenal hormones: adrenocorticotropic hormone (ACTH), cortisol, prolactin, luteinising hormone (LH), follicle-stimulating hormone (FSH) and thyroid-stimulating hormone (TSH).

What was reported. According to the abstract, ipamorelin raised GH but did not produce significant increases in ACTH or cortisol, even at amounts more than 200-fold above the ED50 for GH release. The ED50 is the amount producing half the maximal GH response. The comparator compounds GHRP-6 and GHRP-2 did raise ACTH and cortisol in the same model [1]. This contrast is the basis of the "selective" label.

How to read it. These were animal and cell experiments. Selectivity in swine does not establish the same hormone profile in humans, and a single pharmacology study says nothing about long-term safety. The checklist in How to read peptide research explains why the type of model matters when weighing a finding like this.

Gastrointestinal motility: rodent ileus studies

A second line of research tested ipamorelin in rodent models of postoperative ileus, a temporary slowing of gut movement after abdominal surgery.

• Venkova et al., 2009 (rats). Writing in the Journal of Pharmacology and Experimental Therapeutics, the authors described ipamorelin as a "novel ghrelin mimetic." They examined it in a rat model in which ileus was induced by abdominal surgery with intestinal manipulation, and reported measures of gastrointestinal transit and related outcomes in this model [2].

• Greenwood-Van Meerveld et al., 2012 (rats). A follow-up study in the Journal of Experimental Pharmacology focused on gastric dysmotility, meaning delayed stomach emptying, in a similar rodent model and reported on gastric emptying measures [7].

Both studies used animals. They place ipamorelin within the wider body of work on ghrelin receptor activity and gut motility [3], but they are not evidence about people.

Scope of the evidence in this entry

Every ipamorelin-specific finding summarised above comes from cell and animal experiments. None of the verified sources this entry draws on reports an ipamorelin study in people, so this entry makes no statements about human pharmacology, human study outcomes or effects in humans. That limit is deliberate: the encyclopedia only reports what its listed sources support, and the gap is recorded here rather than filled from secondary summaries.

Several 2026 reviews have surveyed approved and unapproved peptides discussed in sports medicine and orthopaedics [8][9][10]. These reviews are a useful map of the broader landscape and of the regulatory questions around unapproved compounds. They are cited here for context, not as evidence of any specific ipamorelin effect.

Regulatory status

FDA. A search of Drugs@FDA during this entry's status check on 21 October 2026 returned no approved application for an ipamorelin product, so the entry carries the "unapproved" badge. By contrast, Drugs@FDA holds application records for sermorelin (NDA 019863) and tesamorelin (BLA 022505) [11][12]. This finding is dated and will be rechecked when the entry is updated.

Compounding. For substances without an approved product, the FDA regulates whether pharmacies may compound them under section 503A. The agency maintains a page explaining how bulk drug substances are nominated and evaluated for compounding [13]. It also maintains a separate page on certain bulk drug substances that may present significant safety risks [14], and publishes records of its Pharmacy Compounding Advisory Committee, which reviews nominated substances [15]. These pages change over time. This entry does not assert a specific category listing for ipamorelin. Readers who need its current compounding position can consult those FDA pages directly.

Sport. The World Anti-Doping Agency publishes its Prohibited List, which is updated annually [16]. Anti-doping status depends on the edition in force for a given year, so it is verified against the current list rather than secondary summaries.

Further reading

Reading the 1998 selectivity paper or the rodent ileus studies is easier with a grounding in pituitary physiology and peptide chemistry. Our graded list at Peptide science books covers titles at several levels.

When comparing endocrinology or chemistry textbooks for this kind of background reading, these neutral criteria are useful:

• Edition date. Receptor biology has moved quickly, so a recent edition matters for chapters on the pituitary and gut hormones.

• Referencing. Chapters that cite primary literature let readers trace claims back to the original studies.

• Depth on the hypothalamic–pituitary axis. Look for dedicated chapters rather than a single summary page.

• Format and price. Compare print, e-book and rental options, and check whether a used earlier edition covers the same ground.

• Level. Introductory texts suit general readers. Graduate references assume prior biochemistry.

A good general endocrinology text explains how releasing hormones, stomach-derived signals and feedback loops interact. That is the framework needed to read any secretagogue paper critically.

Book recommendations are chosen on the criteria above. Commission arrangements, once in place, do not affect which titles appear or how they are graded.

Frequently asked questions

Is ipamorelin FDA approved?

Our Drugs@FDA status check on 21 October 2026 found no approved ipamorelin product, which is why this entry carries the "unapproved" status badge. Its position for pharmacy compounding falls under the FDA's section 503A framework, which is documented on the agency's compounding pages [13][14].

Is ipamorelin the same as ghrelin?

No. Ghrelin is a natural hormone produced mainly in the stomach. Ipamorelin is a much shorter synthetic peptide that acts at the same receptor, which is why it is described as a ghrelin mimetic [2][3].

Why is ipamorelin called "selective"?

In the 1998 study that introduced it, ipamorelin raised growth hormone in swine without significantly raising ACTH or cortisol, unlike the comparator compounds tested [1]. That finding comes from animals and cultured cells, and it does not by itself establish the same profile in humans.

What did the postoperative ileus studies examine?

Rat studies published in 2009 and 2012 examined ipamorelin in models of post-surgical gut slowing, reporting measures of gastrointestinal transit and gastric emptying [2][7]. Both were animal studies, so they describe findings in rodent models only.

Related on this site

• The A–Z of peptides, one sourced entry at a time

• Sermorelin: history, FDA status and the research record

• Tesamorelin: an approved GHRH analogue, explained

• Peptide FDA status explained: approved to investigational

• Peptide glossary: key terms from agonist to secretagogue

• About Peptide Infinity: how this site works and disclosures

How entries are sourced, and how the site is funded, is explained on the About page.

Last updated: 21 October 2026.

Not medical advice. This page reports published research and regulatory records for information only.

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