Ibutamoren (also known as MK-677) is a potent, synthetic, long-acting, orally-active, selective, and non-peptide agonist of the Ghrelin receptor, Ghrelin mimetic and a Growth hormone secretagogue. Ibutamoren has chemical formula C27H36N4O5S and molar mass 528.662 g/mol. The elimination half-life of Ibutamoren is approximately 4-6 hours, but IGF-1 levels in humans remain elevated at a single oral dose of up to 24 hours