Ipamorelin: Selective Growth Hormone Secretagogue Research Guide

Ipamorelin is a synthetic pentapeptide derived from GHRP-1, recognized as the first selective growth hormone secretagogue with GHRH-like selectivity for GH release. Sequence: Aib-His-D-2-Nal-D-Phe-Lys-NH₂ Ipamorelin is derived from GHRP-1 but lacks the central Ala-Trp dipeptide, contributing to its unique selectivity profile. - Primary Target: Ghrelin/GHS receptor (GHS-R) in the hypothalamus and anterior pituitary - Classification: Selective GHRP-receptor agonist - Triggers GH release via the GHRP-like receptor pathway The mechanism involves: 1. Reduction of somatostatin inhibitory signaling 2. Triggering pulsatile GH secretion mimicking natural circadian rhythms 3. GH surge increases circulating IGF-1 levels 4. IGF-1 drives downstream anabolic effects What distinguishes Ipamorelin from other GHRPs: - Does NOT affect FSH, LH, prolactin, or TSH - Does NOT stimulate ACTH or cortisol (even at very high doses) - Highly selective for growth hormone release only This makes Ipamorelin unique among GHRP-receptor agonists. - Half-life: Approximately 2 hours - Bioavailability: 60-80% recovered intact in bile/urine - Systemic clearance: 5× lower than GHRP-6 Studies show dose-dependent increases in: - Longitudinal growth rate in animal models - Bone formation rate (up to 4× increase) - Reduced bone degradation markers - Enhanced lipolysis pathways - Muscle fiber regeneration through IGF-1 signaling - Insulin potentiation effects Ipamorelin is often studied in combination with: - CJC-1295 for synergistic extended GH release - Administered at night to align with natural GH secretion patterns | Feature | Ipamorelin | GHRP-2/6 | |---------|------------|----------| | Selectivity | High (GH only) | Lower | | Cortisol Effect | None | Increases | | Appetite Effect | Minimal | Increases | Note: This compound is for research purposes only and is not approved for human use.