Ipamorelin
Pentapeptide growth hormone secretagogue with high selectivity for GH release; commonly used in GH-axis research protocols.
Overview
Ipamorelin is a synthetic pentapeptide from the growth hormone-releasing peptide (GHRP) family, developed in the 1990s as an agonist at the ghrelin receptor (GHS-R1a). It is characterized in the research literature as a highly selective growth hormone secretagogue: it stimulates GH release while producing comparatively small effects on appetite, prolactin, and cortisol relative to older GHRP compounds. These properties made it a common choice in research protocols aimed at the GH-IGF-1 axis.
Mechanism
Ipamorelin binds the growth hormone secretagogue receptor 1a on pituitary somatotrophs and hypothalamic neurons, activating intracellular calcium and MAPK signaling that culminate in GH secretion. It acts synergistically with growth hormone-releasing hormone, which is why research protocols frequently combine ipamorelin with a GHRH-class peptide such as Mod GRF 1-29.
Dosing
In research settings ipamorelin is typically given by subcutaneous injection, often once to three times daily in protocols, frequently paired with a GHRH analog. Dosing varies by study and species; exact figures should be sourced from the primary literature, as no approved indication exists.
Expected Effects
- robust, transient increases in circulating growth hormone
- elevated IGF-1 with repeated administration in research protocols
- comparatively modest effects on appetite, prolactin, and cortisol in comparative studies
- enhanced GH pulse amplitude when combined with GHRH-class peptides
Side Effects & Tolerability
The published profile shows a favorable tolerability pattern relative to other secretagogues, with hunger and prolactin changes reported as milder. Remaining considerations are generic to GH-axis stimulation, including potential fluid retention and effects on glucose metabolism with sustained use, plus injection-site reactions.
Storage
Lyophilized ipamorelin should be stored desiccated, protected from light, and kept frozen at -20 deg C or below. Reconstituted solutions should be refrigerated at 2-8 deg C and used promptly, without repeated freeze-thaw cycles.