Ipamorelin

Overview

Ipamorelin is a synthetic pentapeptide growth hormone secretagogue that selectively stimulates growth hormone release from the anterior pituitary gland. Developed in the late 1990s, it is considered one of the most selective GH secretagogues available, binding to the ghrelin receptor (GHS-R1a) with high specificity.

What distinguishes Ipamorelin from other growth hormone secretagogues is its remarkable selectivity — it stimulates GH release without significantly affecting other pituitary hormones such as cortisol, prolactin, or ACTH. This selectivity makes it an exceptionally clean research tool for studying isolated GH-axis effects.

Ipamorelin's pentapeptide structure incorporates non-natural amino acids (Aib and D-2-Nal) that confer resistance to enzymatic degradation while maintaining high receptor binding affinity.

Chemical Profile

Mechanism of Action

Ipamorelin exerts its effects through selective binding to the growth hormone secretagogue receptor type 1a (GHS-R1a), also known as the ghrelin receptor. Unlike ghrelin itself, Ipamorelin binds to GHS-R1a without activating the appetite-stimulating pathways typically associated with ghrelin signaling.

Upon receptor binding, Ipamorelin triggers a signaling cascade in anterior pituitary somatotroph cells involving phospholipase C activation, inositol trisphosphate generation, and intracellular calcium release. This calcium mobilization is the direct trigger for growth hormone vesicle exocytosis — the pulsatile release of GH into circulation.

The selectivity of Ipamorelin is attributed to its specific binding conformation within the GHS-R1a binding pocket, which activates GH release pathways while failing to engage the receptor conformations associated with ACTH, cortisol, or prolactin release.

Research Applications

• Selective growth hormone release mechanisms
• Ghrelin receptor (GHS-R1a) pharmacology
• Bone density and mineral metabolism research
• Body composition and lean mass studies
• IGF-1 axis modulation
• Sleep architecture and GH pulsatility
• Synergistic effects with GHRH analogs

Handling & Reconstitution

1. 1Allow the vial and sterile water to reach room temperature (15–25°C).
2. 2Using a sterile syringe, withdraw the appropriate volume of sterile water.
3. 3Inject the water slowly along the inside wall of the vial — do not spray directly onto the powder.
4. 4Gently swirl the vial until the powder is fully dissolved. Do not shake vigorously.
5. 5Once reconstituted, store at 2°C – 8°C. Protect from light.
6. 6Use within 28 days after reconstitution.
7. 7Do not freeze reconstituted solution.