Ipamorelin The selective GH secretagogue — A complete scientific guide
Ipamorelin, a third-generation synthetic pentapeptide, is one of the most selective growth hormone (GHS) secretagogues studied in research. It is distinguished by its targeted activation of the GHS-R1a receptor without significant effects on cortisol, prolactin, or ACTH.
What is Ipamorelin?
L’Ipamorelin is a synthetic pentapeptide (5 amino acids) with the sequence Aib-His-D-2-Nal-D-Phe-Lys-NH2, developed by Novo Nordisk in the 1990s. It is a selective agonist of the GHS-R1a receptor (Growth Hormone Secretagogue Receptor), the same receptor as that of endogenous ghrelin.
Unlike first-generation GHS (GHRP-6, GHRP-2) which also activate other hormonal pathways, Ipamorelin is characterized by a remarkable selectivity : it stimulates the release of GH without significantly increasing levels of cortisol, aldosterone or prolactin.
Mechanisms of action
Activation of the GHS-R1a receptor
The Ipamorelin binds to GHS-R1a receiver at the level of the anterior pituitary gland and the hypothalamus, mimicking the action of endogenous ghrelin:
- Link to GHS-R1a with activation of the Gq/PLC/IP3/Ca2+ channel
- Depolarization of pituitary somatotroph cells
- Pulsatile release of GH, respecting the physiological pattern
- No rapid desensitization of the receptor (maintenance of efficacy with repeated doses)
Hormonal selectivity
The main characteristic of the Ipamorelin is its unique hormonal profile :
| Hormone | GHRP-6 | GHRP-2 | Ipamorelin |
|---|---|---|---|
| GH (stimulation) | +++ | ++++ | +++ |
| Cortisol | ++ | + | No effect |
| Prolactin | ++ | + | No effect |
| ACTH | + | + | No effect |
| Ghrelin-like (appetite) | +++ | ++ | +/- minimal |
Cascade GH/IGF-1
The GH released under the action of Ipamorelin in turn stimulates hepatic production ofIGF-1 (Insulin-like Growth Factor 1), activating the pathways:
- IGF-1R → PI3K/Akt → protein synthesis and cell survival
- IGF-1R → Ras/MAPK → cell proliferation and differentiation
- Anabolic effects on muscle, cartilage, and bone via these cascades
Research data
Preclinical and clinical studies
| Study | Model | Key result |
|---|---|---|
| Raun et al. 1998 (Novo Nordisk) | Rat / pig | Dose-dependent GH release without cortisol/ACTH effect |
| Phase II postoperative ileus | Human (n=114) | Accelerated return of bowel function |
| Hansen et al. 1999 | Healthy human | GH increase comparable to GHRP-6 without hormonal side effects |
| Johansen et al. 2009 | Human (n=302, Phase II) | Well tolerated, favorable security profile in SC administration |
Pharmacological profile
| Setting | Value |
|---|---|
| Molecular mass | 711.9 Da |
| Half-life | ~2 hours |
| Tmax (peak GH) | ~40 minutes post-SC injection |
| Administrative route | Subcutaneous |
| Active dose (research) | 1 mcg/kg (reference human studies) |
| Therapeutic window | Large (1-10 mcg/kg without cortisol ceiling) |
Synergy with CJC-1295
Ipamorelin is frequently studied in combination with CJC-1295 (GHRH analog) because their mechanisms are complementary:
- CJC-1295 : activates the GHRH-R receptor, increasing GH synthesis in somatotropins
- Ipamorelin : activates GHS-R1a, potentiating the release of already synthesized GH
- The combination produces an effect synergistic (and not simply additive) on the amplitude of GH pulses
- CJC-1295 DAC (Drug Affinity Complex), with its half-life of 6-8 days, provides a basal elevation, while Ipamorelin provides the acute pulses.
For a complete view of the CJC-1295 + Ipamorelin combination, see our dedicated guide on the GH secretagogue duo which details research protocols and combined pharmacokinetics.
Applications in laboratory research
In a scientific research context, Ipamorelin is studied for:
- Studies of pulsatile GH secretion and somatotropic physiology
- Models of sarcopenia and age-related muscle loss
- Research on gastrointestinal motility (post-operative ileus)
- Comparative studies between GH secretagogues (hormonal selectivity)
- Investigation of the GH/IGF-1 axis and its tissue effects
- Models of bone recovery and mineral density
Ipamorelin certified HPLC 99%+ available
MyPeptide offers research-grade Ipamorelin with a Janoshik certificate of analysis. Shipping from the European Union within 48-72 hours.
🧪 Research Peptides — Europe Delivery
≥99% Purity HPLC certified by Janoshik · COA available per batch · Discreet shipping 48-72h
🇫🇷 Retarturate France ·
🇧🇪 Belgium ·
🇩🇪 Germany ·
🇪🇸 Spain ·
🇮🇹 Italy
🇫🇷 GHK-Cu France ·
🇧🇪 Belgium ·
🇩🇪 Germany ·
🇪🇸 Spain ·
→ All countries
📚 Scientific reference:
Raun K et al. “Ipamorelin, the first selective growth hormone secretagogue. » Eur J Endocrinol. 1998.
PubMed PMID:9863230 →