MK-677

Also called ibutamoren. Not a peptide. An oral pill Merck studied. Research only. Not a protocol.

What it is

MK-677 is a small molecule. You swallow it. It binds the ghrelin receptor (GHSR). Ghrelin is the hunger hormone. That receptor also tells the pituitary to release growth hormone in pulses. Then the liver makes IGF-1.

Merck built it so people would not need GH injections. Code names you will see: MK-0677, LUM-201. It never became an approved drug.

Why it is not a peptide

Ghrelin is a peptide. MK-677 is not. It is a synthetic small molecule that copies one of ghrelin’s jobs. Capsules on a peptide shop shelf does not make it a peptide.

What researchers studied

Ian Chapman, Michael Thorner, and colleagues gave oral MK-677 to healthy older adults for up to 4 weeks. Growth hormone pulses got taller. IGF-1 rose into the young-adult range. Fasting glucose also rose.

Ralf Nass, Thorner, and colleagues ran a year-long randomized trial in healthy older adults (Annals of Internal Medicine, 2008). Fat-free mass went up about 1.1 kg on MK-677 and down on placebo. Strength and function did not improve. Appetite went up. Mild ankle swelling showed up. Fasting glucose went up about 5 mg/dL. Insulin sensitivity got worse. People also gained some limb fat and total weight.

That is the honest trial picture: GH and IGF-1 move. Lean mass on a scan moves a little. You do not automatically get stronger. Blood sugar is the trade they kept seeing.

Papers

Chapman, Bach, Van Cauter, Thorner et al., 1996 — Oral MK-677 in healthy elderly. GH and IGF-1 up. Glucose up. Journal of Clinical Endocrinology & Metabolism.

Nass et al., 2008 — One-year randomized trial. Fat-free mass +1.1 kg. No strength gain. Glucose up. Annals of Internal Medicine. Free at PMC2757071.

What this is not

Not a peptide. Not approved GH. Not a proven way to get stronger. This page does not tell you how much to take.

Back to the list · Real GH-releasing peptides on this site: CJC and ipamorelin.