Ipamorelin is a pentapeptide growth hormone secretagogue and selective ghrelin receptor agonist (GHS-R1a). It stimulates GH release from the pituitary gland with exceptional selectivity — producing clean, physiological GH pulses that closely mimic the body's natural nighttime secretion pattern. Unlike earlier-generation GH secretagogues, Ipamorelin shows minimal effect on cortisol, prolactin, or ACTH at research doses, making it one of the most selective GH-stimulating compounds studied to date.