Ibutamoren (INN) (developmental code names MK-677, MK-0677, L-163,191) is a non-peptidic, potent, long-acting, orally-active, and selective agonist of the ghrelin receptor and a growth hormone secretagogue, mimicking the growth hormone (GH)-stimulating action of the endogenous hormone ghrelin. It has been demonstrated to increase the release of, and produces sustained increases in plasma levels of several hormones including GH and insulin-like growth factor 1 (IGF-1), but without affecting cortisol levels. It is currently under development as a potential treatment for reduced levels of these hormones, such as in children or elderly adults with growth hormone deficiency, and human studies have shown it to increase both muscle mass and bone mineral density, making it a promising therapy for the treatment of frailty in the elderly. It also alters metabolism of body fat and so may have application in the treatment of obesity.