MK-677, or Ibutamoren, is a potent, orally-active growth hormone secretagogue, mimicking the ghrelin receptor’s natural ligand, ghrelin. It operates by binding to ghrelin receptors (GHSR) located in the brain, specifically in the pituitary gland and hypothalamus. This activation modulates the release of growth hormone (GH) and increases plasma levels of insulin-like growth factor 1 (IGF-1).