Ipamorelin is a synthetic pentapeptide that binds the ghrelin receptor and stimulates the release of growth hormone from the pituitary gland. In research it is known for its selectivity: animal studies found that it prompts growth hormone release with little effect on other pituitary hormones. This guide explains what ipamorelin is, how it works, where it has been studied and how to handle it in the lab.
What is ipamorelin?
Ipamorelin belongs to the growth hormone secretagogue family, a group of synthetic compounds that act on the growth hormone secretagogue receptor type 1a (GHS-R1a), the same receptor activated by the natural hunger hormone ghrelin. It was developed in the 1990s as part of an effort to design secretagogues with a cleaner profile than earlier growth hormone releasing peptides such as GHRP-6 and GHRP-2.
Structurally, ipamorelin is a five-residue peptide that contains non-natural amino acids, including aminoisobutyric acid and D-configured aromatic residues, with an amidated C-terminus. These modifications make it more resistant to enzymatic breakdown than a comparable natural peptide and shape its receptor selectivity. It has also been referred to by the development code NNC 26-0161.
Ipamorelin is a research compound. It is not an approved medicine in the US. It has been investigated in clinical studies, including in the context of gastrointestinal motility after surgery, but it did not reach approval.
How ipamorelin works: mechanism studied in research
Growth hormone release from the pituitary is controlled by two main hypothalamic signals: growth hormone releasing hormone (GHRH), which stimulates release, and somatostatin, which suppresses it. Ghrelin and the synthetic secretagogues add a third input through GHS-R1a.
In research models, ipamorelin has been shown to:
- Bind and activate GHS-R1a on pituitary somatotroph cells, triggering growth hormone release
- Produce a pulse of growth hormone rather than a sustained elevation, in line with the body's normal pulsatile pattern
- Show little effect on ACTH and cortisol in animal studies, which set it apart from earlier secretagogues
- Show little effect on prolactin in the same animal work
Because GHRH analogs and ghrelin receptor agonists act through different receptors and signaling pathways, researchers often study them together. Pairing ipamorelin with a GHRH analog such as CJC-1295 without DAC is a common model for exploring how the two inputs interact at the pituitary.
Ghrelin receptors are also found outside the pituitary, including in the gut and in the brain. This wider distribution explains why ipamorelin has been studied in gastrointestinal motility research as well as in growth hormone research.
Ipamorelin compared with other secretagogues
Ipamorelin is one of several synthetic ghrelin receptor agonists used in research. GHRP-6 and GHRP-2 were earlier peptides in the same family and are associated in the literature with stronger effects on appetite and on stress-related hormones. Hexarelin is another potent secretagogue studied partly for cardiac receptor effects. Non-peptide agonists such as ibutamoren (MK-677) act on the same receptor but are orally active small molecules with a longer duration of action. Against this background, ipamorelin is typically chosen when a study needs a short-acting peptide agonist with a narrow hormonal profile, so that growth hormone effects can be separated from changes in cortisol or prolactin.
Areas of research
Ipamorelin has been studied in cell, animal and some clinical settings. Research areas include:
- Growth hormone secretion: the pattern, size and selectivity of growth hormone release in animal models
- Pituitary signaling: interactions between the ghrelin receptor pathway and the GHRH pathway
- Gastrointestinal motility: ghrelin receptor effects on gut transit, including clinical investigation in postoperative settings
- Bone and body composition: growth hormone axis effects on bone and lean tissue in rodent models
- Receptor pharmacology: ipamorelin as a reference agonist when comparing ghrelin mimetics
Ipamorelin key facts table
| Property | Detail |
|---|---|
| Compound class | Synthetic peptide, growth hormone secretagogue |
| Target | Ghrelin receptor (GHS-R1a) |
| Structure | Pentapeptide with non-natural amino acids and an amidated C-terminus |
| Form supplied | Lyophilized powder in a sealed vial |
| Research status | Research compound; not an approved medicine in the US |
| Common research models | Pituitary cell assays, rodent growth hormone and GI motility models |
| Storage | Lyophilized: cold, dry, dark. Reconstituted: refrigerated |
Handling and storage in the lab
Ipamorelin is supplied as a lyophilized (freeze-dried) powder, which is the most stable form for storage and shipping. General lab handling points:
- Before opening: let the vial reach room temperature to limit condensation inside it.
- Reconstitution: for lab use, peptides like ipamorelin are commonly reconstituted with bacteriostatic water. Add the diluent slowly down the side of the vial and swirl gently rather than shaking, which can damage peptides.
- Storage before reconstitution: keep sealed vials cold, dry and away from light. A freezer suits long-term storage and a refrigerator suits shorter periods.
- Storage after reconstitution: keep the solution refrigerated and protected from light, and avoid repeated freeze-thaw cycles.
- Record keeping: label vials with the compound, diluent, preparation date and lot number.
Bacteriostatic water contains a small amount of benzyl alcohol as a preservative, which limits microbial growth in multi-use vials. For assays that are sensitive to preservatives, such as some cell-based experiments, sterile water or an appropriate buffer may be the better diluent. Whatever the choice, keep the diluent consistent across experimental groups and record it with the results.
Quality and lab results
Secretagogue research depends on knowing that the peptide in the vial is the intended sequence, since closely related growth hormone releasing peptides act on the same receptor with different selectivity. Every PRIME batch is tested, and the certificate of analysis for each lot is published so researchers can check identity and purity before use. Current reports are available on the lab results (COA) page.
Research material is available as ipamorelin and as the CJC-1295 no DAC and ipamorelin blend.
Related research
- CJC-1295 vs Ipamorelin: how a GHRH analog and a ghrelin receptor agonist differ
- Ipamorelin vs Tesamorelin: a secretagogue compared with an approved GHRH analog
- CJC-1295 and ipamorelin blend guide: why the two are studied together
Ipamorelin FAQ
What is ipamorelin?
Ipamorelin is a synthetic five-residue peptide that activates the ghrelin receptor (GHS-R1a) and stimulates growth hormone release from the pituitary. It is classed as a growth hormone secretagogue and is supplied by PRIME for laboratory research.
Why is ipamorelin described as selective?
In animal studies, ipamorelin produced growth hormone release with little change in ACTH, cortisol or prolactin. Earlier secretagogues such as GHRP-6 and GHRP-2 were associated with broader hormonal effects in comparable research.
What is the difference between ipamorelin and CJC-1295?
They act through different receptors. Ipamorelin is a ghrelin receptor agonist, while CJC-1295 is an analog of GHRH that acts on the GHRH receptor. Because the pathways are distinct, researchers often study them in combination.
Is ipamorelin FDA approved?
No. Ipamorelin is not an approved medicine in the US. It has been investigated in clinical studies but is sold by PRIME only as a research compound, not for human consumption.
How should ipamorelin be stored?
Store lyophilized vials cold, dry and away from light. After reconstitution for lab use, keep the solution refrigerated, protected from light, and avoid repeated freezing and thawing.
For laboratory research use only. Not for human consumption. Not a drug, food or cosmetic.