GHRP-6

Research-Grade

GHRP-6 is the synthetic hexapeptide His-DTrp-Ala-Trp-DPhe-Lys-NH2, first described by Bowers and colleagues in 1984 as a peptide that acts on the pituitary to release growth hormone in a dose-related way across several animal species. Work on synthetic GH secretagogues later led to the 1996 cloning of their receptor, a G-protein-coupled receptor in the pituitary and hypothalamus — now known as the ghrelin receptor — at a time when its natural hormone had not yet been identified. In 18 healthy men, intravenous GHRP-6 at 0.1–1.0 mcg/kg raised GH in a dose-dependent way (mean peak about 69 mcg/L at 1 mcg/kg) and acted synergistically with GHRH, suggesting the two act through independent pathways. At the highest dose, prolactin and cortisol rose about two-fold above baseline; no adverse clinical effects or laboratory abnormalities were reported in that acute study. In swine, GHRP-6 raised ACTH and cortisol, whereas the later compound ipamorelin did not. In rats, GHRP-6 injected into the brain ventricles stimulated eating independently of its effect on GH. GHRP-6 is not an approved medicine. Human data are limited to short, mostly single-dose studies, and the FDA lists GHRP-6 among bulk drug substances that may present significant safety risks in compounding.