Ipamorelin: The Selective GHRP and Growth Hormone Secretagogue
An evidence-based guide to Ipamorelin, a pentapeptide growth hormone secretagogue (Aib-His-D-2-Nal-D-Phe-Lys-NH2) known for its high selectivity for ghrelin receptors and minimal cortisol and prolactin elevation.
Introduction
Ipamorelin is a synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) belonging to the growth hormone-releasing peptide (GHRP) family. It functions as a selective agonist of the ghrelin/growth hormone secretagogue receptor (GHS-R1a), stimulating endogenous growth hormone release through a distinctly different mechanism than growth hormone-releasing hormone (GHRH).
Chemical Profile
- Sequence: Aib-His-D-2-Nal-D-Phe-Lys-NH2
- Molecular Formula: C38H49N9O5
- Molecular Weight: ~711.9 g/mol
- CAS Number: 170851-70-4
- Appearance: White to off-white lyophilized powder
Mechanism of Action
Ghrelin Receptor Agonism
Ipamorelin binds to GHS-R1a receptors in the anterior pituitary and hypothalamus, mimicking the action of endogenous ghrelin. This binding triggers a cascade that stimulates growth hormone (GH) release from somatotroph cells.
Selectivity Profile
Ipamorelin is distinguished from other GHRPs by its exceptional selectivity:
| Parameter | Ipamorelin | GHRP-6 | GHRP-2 |
|---|---|---|---|
| GH release | Moderate-strong | Strong | Strong |
| Cortisol elevation | None | Moderate | Mild |
| Prolactin elevation | None | Mild | Mild |
| ACTH elevation | None | Moderate | Mild |
| Appetite stimulation | Minimal | Strong | Moderate |
This clean profile makes Ipamorelin particularly valuable for research requiring GH pathway activation without confounding hormonal effects.
Synergy with GHRH Analogues
Ipamorelin acts synergistically with GHRH analogues (such as CJC-1295). The complementary mechanisms—GHS-R1a agonism versus GHRH receptor agonism—produce a greater-than-additive GH pulse when co-administered.
Preclinical and Clinical Research
Growth Hormone Release
- Stimulates a physiologically pulsatile GH release pattern
- Peak GH levels achieved 15-30 minutes post-administration
- GH levels return to baseline within 2-3 hours
Body Composition Effects
In research models, Ipamorelin administration is associated with:
- Increased lean body mass
- Enhanced lipolysis (fat oxidation)
- Improved nitrogen retention
- Accelerated wound healing and tissue repair
Sleep Architecture
GH secretagogues influence slow-wave sleep (SWS) architecture. Ipamorelin may enhance SWS duration, which is the primary period of endogenous GH secretion.
Analytical Specifications
| Parameter | Specification |
|---|---|
| Purity | >= 99% (HPLC) |
| Identity | Confirmed by MS |
| Peptide content | >= 85% (NPN) |
| Bacterial endotoxins | < 10 EU/mg |
| Residual solvents | < ICH Q3C limits |
Frequently Asked Questions
What is the difference between Ipamorelin and sermorelin?
Ipamorelin acts on ghrelin receptors (GHS-R1a) while sermorelin acts on GHRH receptors. They use completely different pathways to stimulate GH release.
Is Ipamorelin the most selective GHRP?
Yes, Ipamorelin is widely considered the cleanest GHRP with minimal effects on cortisol, prolactin, and ACTH.
What is the CAS number for Ipamorelin?
The CAS number is 170851-70-4.
Storage and Handling
- Store at -20C as lyophilized powder
- Protect from light and moisture
- Reconstitute with bacteriostatic water (2mL typical)
- Reconstituted solution: stable 30 days at 2-8C
Conclusion
Ipamorelin's high selectivity and clean pharmacological profile make it an essential research tool for studies investigating growth hormone physiology, body composition regulation, and tissue repair mechanisms.
All products sold by Kingston Peptides are intended exclusively for in vitro research and analytical purposes.