Ipamorelin
Growth-hormone secretagogue (GHRP) / ghrelin receptor agonist
A selective GH-secretagogue peptide studied in pulsatile GH-release research.
Also referenced as: NNC 26-0161
Overview
Ipamorelin is a synthetic pentapeptide developed in the 1990s (originally by Novo Nordisk) as a selective growth-hormone secretagogue. It was designed to stimulate GH release with minimal off-target hormonal effects.
At a glance
What Ipamorelin does
Ipamorelin is a synthetic pentapeptide that acts as a selective agonist of the growth hormone secretagogue receptor (GHS-R1a), the same receptor targeted by the natural hunger hormone ghrelin. By binding this receptor on somatotroph cells of the anterior pituitary, it triggers a discrete pulse of growth hormone (GH) release. Mechanistically it works on a different axis than GHRH: rather than raising the ceiling on GH output, it amplifies the pituitary's readiness to release stored GH, and it also blunts somatostatin, the brake that normally suppresses GH secretion. The result in research models is a clean, pulse-like rise in GH followed by a secondary rise in liver-derived IGF-1.
What distinguishes ipamorelin from earlier ghrelin mimetics like GHRP-2 and GHRP-6 is its selectivity. In animal studies it stimulates GH without the meaningful increases in cortisol, ACTH, or prolactin that the older peptides cause, and it has little of the appetite-driving effect associated with GHRP-6. This selectivity is its signature research finding. Because ghrelin-receptor agonists and GHRH analogs act on complementary pathways, ipamorelin is frequently studied alongside a GHRH analog (such as CJC-1295 no-DAC), where the two produce a synergistic GH pulse larger than either alone.
Evidence is largely preclinical (rodent and in-vitro pituitary cell work) with some early human pharmacology; ipamorelin is not an approved drug. Its studied actions center on GH/IGF-1 elevation and downstream effects on lean tissue and bone rather than proven clinical outcomes.
Effects reported in research
- Selectively stimulated a pulse-like release of growth hormone from pituitary somatotrophs via GHS-R1a agonism (animal and in-vitro pituitary cell studies).
- Raised circulating IGF-1 downstream of the GH pulse in animal models.
- Did NOT meaningfully elevate cortisol, ACTH, or prolactin in preclinical work, unlike GHRP-2 and GHRP-6 (its hallmark selectivity finding).
- Produced little of the strong appetite stimulation seen with GHRP-6, since it drives GH with minimal off-target ghrelin-pathway activation (animal data).
- Suppressed somatostatin tone, disinhibiting GH release, in mechanistic studies.
- Increased bone mineral content / promoted longitudinal bone growth in young rat models.
- Acted synergistically with GHRH analogs to amplify GH output when co-administered (preclinical combination studies).
- No large human clinical efficacy trials; effects on human body composition remain unproven and research-use only.
Effects listed reflect findings reported in the research literature — many in animal or in-vitro models. Listing an effect is not a claim of efficacy or a therapeutic indication in humans.
Mechanism of action
Ipamorelin is an agonist of the growth-hormone secretagogue receptor (GHS-R1a, the ghrelin receptor), mimicking ghrelin to stimulate GH release from the anterior pituitary. It acts on the pituitary and hypothalamus to promote a pulsatile release of growth hormone. Unlike some other GHRPs, it is reported to be highly selective, releasing GH without significantly stimulating ACTH, cortisol, or prolactin at effective doses.
Mechanistic description reflects published research-literature understanding. Much peptide research is preclinical (in-vitro or animal-model); mechanism in humans may differ and is not established for many compounds.
What it's studied for
Research contexts in which Ipamorelin appears in the literature. Listing a research area is not a claim of efficacy or a therapeutic indication.
Key characteristics
- Selective GHS-R1a (ghrelin receptor) agonist
- Reported to release GH with minimal effect on cortisol and prolactin, distinguishing it from GHRP-6 and hexarelin
- Pentapeptide with unnatural amino acids (Aib, D-2-Nal, D-Phe) conferring stability and selectivity
- Often studied combined with a GHRH analog (e.g. CJC-1295) for synergistic GH pulses
- Does not strongly stimulate hunger compared with GHRP-6
Reported research dosing reference only
Educational reference, not dosing guidance. The figures below summarize amounts reported in published research and research-community protocols, provided for educational and research context only. They are not medical advice, not a recommendation, and not instructions for human use. Ipamorelin is a research compound.
In the research literature, ipamorelin is typically referenced at roughly 2-3 mcg/kg per administration, which corresponds to about 100-300 mcg per dose for a 70 kg subject-equivalent. These are reference figures for research context only, not dosing guidance for humans.
- Body-weight-scaled reference: ~2-3 mcg/kg per dose
- Common research-protocol reference: 100-300 mcg per subcutaneous administration
- Multi-pulse study designs: dosing 1-3 times per day
~2 hour half-life means each dose is a discrete GH pulse; reference figures only, not human dosing guidance.
How it compares
Among GHRPs, ipamorelin is noted for its selectivity — stimulating GH release without the appetite, cortisol, and prolactin elevations associated with GHRP-6 and hexarelin.
Commonly studied alongside
Compounds frequently researched together with Ipamorelin in the literature. Cross-referenced for research context — not a usage or combination recommendation.
Compare and calculate
Side-by-side pages for the pairings the literature already documents for Ipamorelin, plus the unit-conversion reference for a reconstituted vial. Factual comparisons of documented characteristics — not a recommendation to combine or use any compound.
Handling & Stability
Lyophilized peptides are stored cold, protected from light, and reconstituted only at the time of intended in-vitro work.
- Avoid repeated freeze-thaw cycles
- Verify supplier lot and Certificate of Analysis
- Follow institutional lab-safety protocols
Analytical & COA Concepts
Reputable research suppliers publish a third-party Certificate of Analysis per batch. Key analytical concepts referenced in COAs include:
Category Context
Ipamorelin sits in the Growth & GH-Axis area of the PeptiDex library.
- Entry type: Research compound reference
- Growth & GH-Axis category hub →
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- Glossary of terms →
Where researchers source Ipamorelin
For researchers studying Ipamorelin, third-party suppliers such as Practically Natty Peptides offer research-grade material, third-party tests every batch and provides Certificates of Analysis on request, and ship from the US.
View research-supplier listing →
Outbound link to a third-party research supplier. Inclusion does not constitute endorsement; all editorial content is developed independently.
Frequently asked questions
What is ipamorelin and what class of compound is it?
Ipamorelin is a synthetic pentapeptide growth hormone secretagogue (a ghrelin/GHS-R1a receptor agonist). It is studied as one of the most selective GHRPs, stimulating pulsatile GH release from the anterior pituitary with minimal effect on cortisol, prolactin, or ACTH in research models.
How does ipamorelin differ from GHRP-2 and GHRP-6?
All three activate the ghrelin receptor (GHS-R1a), but ipamorelin is the most selective: in the research literature it drives GH release without the appetite stimulation seen with GHRP-6 or the cortisol/prolactin elevation associated with GHRP-2. This selectivity is why it is frequently used as a reference GHRP in study design.
Why is ipamorelin commonly studied alongside a GHRH analog like CJC-1295?
Ipamorelin (a GHS-R agonist) and a GHRH analog such as CJC-1295 or sermorelin act on two different receptor pathways. Research protocols pair them because combined GHRH + GHRP stimulation produces a synergistic, amplified GH pulse greater than either compound alone.
What does ipamorelin's short half-life imply for research design?
With a terminal half-life of roughly 2 hours, each administration in the research literature produces a discrete GH pulse that then fades. Studies examining pulsatile GH physiology often use this property, and multi-dose-per-day protocols are used when sustained stimulation is the research objective.
Is ipamorelin an approved drug?
No. Ipamorelin is not an FDA-approved medication. It was investigated in early clinical studies but is offered only as a research chemical and is not approved for human therapeutic use.
Answers are educational summaries of research-literature context and do not constitute medical advice. See the Research Library, COA guide, and Storage & Handling guide for more.
References
Primary literature indexed in PubMed for Ipamorelin. Listing a study records that it exists and is indexed — it is not a claim of efficacy, a therapeutic indication, or an endorsement of its conclusions. Much of this literature is preclinical (in-vitro or animal-model).
- Ipamorelin, the first selective growth hormone secretagogue
- Efficacy of ipamorelin, a novel ghrelin mimetic, in a rodent model of postoperative ileus
Each reference was checked against its PubMed record on 2026-07-28: the PMID resolves and the title, journal and year match. Where no indexed literature exists for a compound, PeptiDex says so rather than substituting a citation about a different molecule. See the editorial policy.