MK-677 is a drug which acts as a potent, orally active growth hormone

Growth hormone

Growth hormone is a peptide hormone that stimulates growth, cell reproduction and regeneration in humans and other animals. Growth hormone is a 191-amino acid, single-chain polypeptide that is synthesized, stored, and secreted by the somatotroph cells within the lateral wings of the anterior...

 secretagogue, mimicking the GH stimulating action of the endogenous hormone ghrelin

Ghrelin

Ghrelin is a 28 amino acid peptide and hormone that is produced mainly by P/D1 cells lining the fundus of the human stomach and epsilon cells of the pancreas that stimulates hunger. Ghrelin levels increase before meals and decrease after meals. It is considered the counterpart of the hormone...

. It has been demonstrated to increase the release of, and produces sustained increases in plasma levels of several hormones including growth hormone and IGF-1, but without affecting cortisol

Cortisol

Cortisol is a steroid hormone, more specifically a glucocorticoid, produced by the adrenal gland. It is released in response to stress and a low level of blood glucocorticoids. Its primary functions are to increase blood sugar through gluconeogenesis; suppress the immune system; and aid in fat,...

 levels. It is currently under development as a potential treatment for reduced levels of these hormones, such as in growth hormone deficient children or elderly adults, 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

Sarcopenia

Sarcopenia is the degenerative loss of skeletal muscle mass and strength associated with aging...

. It also alters metabolism of body fat and so may have application in the treatment of obesity

Obesity

Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and/or increased health problems...

.