MK-677

MK-677 (Ibutamoren)

MK-677, also known as Ibutamoren or MK-0677, is a synthetic non-peptide ghrelin receptor agonist and growth hormone secretagogue (GHS) developed by Merck & Co. Unlike peptide-based GHS compounds, MK-677 is orally bioavailable and has a prolonged half-life of approximately 24 hours, making it a practical research tool for sustained GH axis stimulation. It has been extensively studied in preclinical and clinical research for its effects on GH and IGF-1 secretion, body composition, bone density, sleep architecture, and metabolic regulation.

Mechanism of Action

MK-677 acts as a potent, selective agonist of the ghrelin receptor (GHSR-1a), a G-protein-coupled receptor expressed in the hypothalamus and pituitary. GHSR-1a activation stimulates pulsatile GH release from pituitary somatotrophs via a mechanism that is additive with endogenous GHRH signalling and partially independent of somatostatin inhibition. The resulting GH pulses drive hepatic IGF-1 production, which mediates downstream anabolic, lipolytic, and tissue-remodelling effects. MK-677 also activates hypothalamic neuropeptide Y (NPY) pathways, stimulating appetite — a characteristic feature of ghrelin receptor agonism that is of research interest in cachexia and metabolic disease models.

Research Applications

• Ghrelin receptor (GHSR-1a) pharmacology and GH secretagogue studies
• GH and IGF-1 axis stimulation and somatotropic signalling research
• Body composition, lean mass, and adipose tissue metabolism investigation
• Bone mineral density and skeletal remodelling preclinical models
• Sleep architecture, REM sleep, and slow-wave sleep research

Specifications

• Molecular Formula: C₂₇H₃₆N₄O₅S • CH₄O₃S
• Molecular Weight: 624.8 g/mol
• CAS Number: 159752-10-0
• Purity: ≥98%
• Form: Lyophilised powder
• Storage: -20°C
• Shelf Life: 24 months

This product is intended for legitimate laboratory and analytical research use only. Not for diagnostic, therapeutic, or consumer use.