MK-677

MK-677 (Ibutamoren) is an orally active ghrelin mimetic that binds the GHS-R1a receptor to stimulate sustained growth hormone and IGF-1 secretion without requiring injection.

In a year-long randomized human trial in older adults, daily MK-677 raised IGF-1 levels by 84 percent compared with 17 percent on placebo and increased fat-free mass by about 1.1 kg, though it did not improve measured strength or physical function.

These findings have kept MK-677 a widely studied tool for research into the GH/IGF-1 axis, body composition, and the aging somatotropic system.