MK-677
Research OnlyModerate EvidenceMK-677 (Ibutamoren / Ibutamoren Mesylate)
An orally active, non-peptide GH secretagogue that mimics ghrelin to stimulate sustained GH and IGF-1 elevation — the only orally bioavailable GHS-R agonist widely available, but not a peptide.
Half-Life
~24 hours (oral)
Molecular Weight
624.8 g/mol
MK-677 (ibutamoren) is a non-peptide, orally active GH secretagogue developed by Merck. It acts as a potent ghrelin mimetic, binding the GHS-R1a receptor and stimulating pulsatile GH release and downstream IGF-1 production. Unlike peptide GH secretagogues (CJC-1295, Ipamorelin, GHRP-2), MK-677 is orally bioavailable with a ~24-hour half-life, making it extremely convenient — a single daily oral dose produces sustained GH/IGF-1 elevation throughout the day. It has been studied in phase I/II trials for GH deficiency, muscle wasting, osteoporosis, and Alzheimer's disease, with generally positive results for GH/IGF-1 elevation, lean mass preservation, and bone density. It is technically not a peptide — it is a small molecule spiroindoline compound — but it is widely sold alongside peptides and fits squarely in the GH secretagogue category. Phase III trials were not completed; it remains research-only.
Also Known As
Amino Acid Sequence
N/A — small molecule, not a peptide
Reconstitution
Sold as oral liquid or capsules. No reconstitution required. Take with or without food; some prefer evening dosing to align with sleep-related GH pulses.
Open Reconstitution Calculator →