What Is Ipamorelin?
Ipamorelin is a synthetic pentapeptide growth hormone secretagogue (GHS) that selectively activates the ghrelin receptor (also known as the growth hormone secretagogue receptor, GHSR). Unlike GHRH analogues such as CJC-1295 or Tesamorelin, which act at the GHRH receptor on pituitary somatotrophs, Ipamorelin acts through a distinct receptor pathway to stimulate growth hormone release.
Ipamorelin was developed by Novo Nordisk in the late 1990s as part of a program investigating selective GH secretagogues for potential metabolic and anabolic applications. Its key differentiating feature in the research literature is its reported selectivity for GH release without significant concurrent stimulation of ACTH (adrenocorticotropic hormone), cortisol, or prolactin — a profile that distinguishes it from earlier, less selective GH secretagogues like GHRP-6 and GHRP-2.
Ipamorelin is not approved for human use by Health Canada or any major regulatory authority. In Canada, it is classified as a research compound available for in-vitro and laboratory research only. This overview provides educational context for researchers investigating GH-axis peptide pharmacology.
Chemical Profile and Structure
Ipamorelin is a pentapeptide with the sequence Aib-His-D-2-Nal-D-Phe-Lys-NH₂. Its compact five-amino acid structure is a result of structure-activity relationship (SAR) research aimed at optimizing GH-releasing potency while minimizing off-target secretagogue effects on ACTH and cortisol.
Key Chemical Characteristics
- Type: Synthetic pentapeptide GH secretagogue
- Sequence: Aib-His-D-2-Nal-D-Phe-Lys-NH₂
- Molecular Weight: ~711.87 Da
- CAS Number: 170851-70-4
- Receptor Target: GHSR (Ghrelin Receptor / Growth Hormone Secretagogue Receptor)
- Physical Form: Lyophilized white powder
- Solubility: Soluble in water and aqueous buffers
Non-Natural Amino Acid Components
Ipamorelin contains several non-natural amino acid components that contribute to its metabolic stability and receptor selectivity:
- Aib (α-aminoisobutyric acid): A non-natural alpha-methylated amino acid that confers rigidity and DPP-IV resistance
- D-2-Nal (D-2-naphthylalanine): An aromatic D-amino acid important for GHSR binding
- D-Phe (D-phenylalanine): D-amino acid configuration for receptor interaction
Research Background
Ipamorelin emerged from Novo Nordisk’s research program into growth hormone secretagogues in the late 1990s. The development context was a search for compounds that could stimulate GH release with greater selectivity than first-generation GHS peptides like GHRP-6, which was noted to also increase ACTH and cortisol in animal models — a secondary effect considered undesirable for potential clinical applications.
The published research on Ipamorelin demonstrated its high potency for GH release via the GHSR while documenting minimal concurrent stimulation of ACTH and cortisol in animal studies. This selectivity profile became a defining characteristic of Ipamorelin in the research literature.
Novo Nordisk advanced Ipamorelin through preclinical research and into early clinical development but ultimately did not pursue it to regulatory approval. The compound has since become a widely researched reference compound for GHS receptor pharmacology.
For broader context on GH-axis research peptides, see research peptides explained and research peptides in Canada.
Mechanisms of Interest in Research
Ipamorelin’s mechanism of action involves selective activation of the GHSR (ghrelin receptor), triggering intracellular signalling cascades that ultimately result in GH secretion from pituitary somatotrophs.
GHSR Activation
Ipamorelin binds to the GHSR-1a (the primary active form of the ghrelin receptor), a Gq-protein coupled receptor. Activation of GHSR triggers phospholipase C signalling, intracellular calcium mobilization, and downstream GH secretion from somatotrophs.
Somatostatin Modulation
Research suggests that GH secretagogues acting via the ghrelin receptor may partially suppress somatostatin (growth hormone-inhibiting hormone) release from the hypothalamus, which amplifies the GH response. This is thought to be a component of the synergistic effect observed when ghrelin-pathway GHS compounds are combined with GHRH-pathway compounds in animal research.
Complementary Action with GHRH Analogues
One of the most researched aspects of Ipamorelin’s pharmacology is its synergistic interaction with GHRH-pathway compounds. Because Ipamorelin (via GHSR) and GHRH analogues like CJC-1295 (via GHRHR) activate distinct but converging pathways in somatotrophs, simultaneous activation in animal models produces synergistic GH responses greater than either compound alone.
Ipamorelin Within the GH Secretagogue Research Class
Ipamorelin belongs to a class of synthetic compounds known as GH secretagogues (GHS), which includes both peptide and non-peptide compounds acting via the ghrelin receptor. Understanding its position within this class is important for research context:
| Compound | Type | Receptor | ACTH/Cortisol Effect | Notes |
|---|---|---|---|---|
| Ipamorelin | Pentapeptide GHS | GHSR | Minimal (in animal models) | High selectivity for GH |
| GHRP-6 | Hexapeptide GHS | GHSR | Significant | Earlier, less selective GHS |
| GHRP-2 | Hexapeptide GHS | GHSR | Significant | More potent but less selective |
| MK-0677 (Ibutamoren) | Non-peptide GHS | GHSR | Some increase | Orally active, long half-life |
| CJC-1295 | GHRH analogue | GHRHR | None (different pathway) | Complementary to Ipamorelin |
Preclinical Research Overview
The published preclinical literature on Ipamorelin has examined several research themes:
GH Secretion Studies
Original published research from Novo Nordisk documented Ipamorelin’s potent, selective, dose-dependent GH release in rat and porcine models, establishing the compound’s selectivity profile and potency relative to earlier GHS compounds.
Bone Metabolism Research
Some preclinical research has examined Ipamorelin’s effects on bone mineral density parameters and osteoblast activity in animal models, investigating whether GH axis stimulation via GHSR may influence bone metabolism endpoints. These are early-stage findings.
Body Composition in Animal Models
Animal research has examined the effects of sustained Ipamorelin administration on body composition parameters including lean mass and adipose tissue distribution in rodent models. These findings are model-specific and should not be interpreted as evidence of human body composition effects.
Gastrointestinal Research
The ghrelin receptor (GHSR) is distributed not only in the pituitary but also throughout the gastrointestinal tract. Some research has examined Ipamorelin’s effects on GI motility in animal models, an area of research interest given ghrelin’s known role in GI physiology.
For related reading on research goals involving GH-axis compounds, see our articles on peptides for longevity research and peptides for metabolic research.
Selectivity Profile in Research
The selectivity of Ipamorelin for GH release over ACTH and cortisol is one of its most scientifically discussed attributes. In published animal studies, Ipamorelin produced minimal or statistically non-significant increases in ACTH and cortisol at GH-releasing doses, in contrast to GHRP-6 and GHRP-2 which produced significant concurrent ACTH and cortisol elevations.
This selectivity profile has made Ipamorelin a preferred research tool for investigators wishing to study GH/IGF-1 axis stimulation in isolation from glucocorticoid axis activation. However, it is important to note that selectivity observed in animal models may not translate directly to human pharmacology.
For compliance and safety context in Canadian research, see research compound safety and compliance.
Storage and Handling
Recommended Storage Conditions
- Long-term (lyophilized): −20°C or below
- Short-term: 2–8°C for up to several weeks
- Post-reconstitution: Refrigerate at 2–8°C; avoid repeated freeze-thaw
- Avoid: Direct light, humidity, elevated temperatures
See our peptide storage guide and peptide reconstitution guide.
Purity and Testing Standards
- HPLC Purity: ≥98% for research-grade Ipamorelin
- Mass Spectrometry: Confirms pentapeptide identity and detects impurities
- CoA Required: All research-grade compounds should include a Certificate of Analysis
See what is a CoA? and how TrueCanPeptides tests compounds.
Related Research Compounds
- CJC-1295: GHRH analogue frequently studied alongside Ipamorelin for synergistic GH-axis research
- Tesamorelin: Full-length GHRH analogue with regulatory approval for specific indication
- Metabolic Research Peptides: Broader overview of peptides in metabolic research
- Longevity Research Peptides: Peptides investigated in aging and longevity research contexts
Frequently Asked Questions
Q: What is Ipamorelin?
Ipamorelin is a synthetic pentapeptide GH secretagogue that selectively activates the ghrelin receptor (GHSR) to stimulate GH release. Developed by Novo Nordisk, it is notable for its selectivity: potent GH release with minimal ACTH/cortisol stimulation in animal models. Not approved for human use in Canada — research compound only.
Q: How does Ipamorelin differ from CJC-1295?
Ipamorelin acts via GHSR (ghrelin receptor); CJC-1295 acts via GHRHR (GHRH receptor). Distinct pathways, complementary mechanisms. Together they produce synergistic GH responses in animal models. See CJC-1295 vs Ipamorelin comparison.
Q: Is Ipamorelin approved for human use in Canada?
No. Not approved by Health Canada. Classified as a research compound for in-vitro and laboratory use only.
Q: Why is Ipamorelin considered selective compared to other GH secretagogues?
In animal studies, Ipamorelin produces significant GH release with minimal concurrent ACTH and cortisol stimulation — unlike earlier GHS compounds (GHRP-6, GHRP-2) which produce more pronounced secondary hormone responses. This makes it a useful research tool for isolated GH/IGF-1 axis investigation.
Q: What preclinical research areas has Ipamorelin been studied in?
GH secretion selectivity, bone metabolism, body composition in rodent models, GI motility (via GHSR distribution in GI tract), and synergistic GH responses with GHRH-pathway compounds.
Related Articles
- What Is CJC-1295? Research Overview
- CJC-1295 vs Ipamorelin: Research Comparison
- What Is Tesamorelin? Research Overview
- Tesamorelin vs HGH: Research Comparison
- Peptides for Metabolic Research
- Peptides for Longevity Research
Disclaimer: All compounds discussed on this page are intended strictly for laboratory and research purposes. They are not approved for human use, are not intended to diagnose, treat, cure, or prevent any disease or condition, and should not be used outside of a controlled research environment. TrueCanPeptides does not provide medical advice. Consult a qualified healthcare professional before making any health-related decisions. Research compounds are sold for in-vitro and laboratory use only.