MK-677 (Ibutamoren)
Oral GH secretagogue and ghrelin receptor agonist with non-peptide structure enabling once-daily oral dosing
MK-677 (Ibutamoren, Nutrobal) is a non-peptide GH secretagogue that acts as a potent, orally active agonist of the ghrelin receptor (GHS-R1a). Unlike peptide-based GH secretagogues that require injection, MK-677's non-peptide structure makes it bioavailable orally with a half-life of approximately 24 hours, enabling convenient once-daily dosing.
MK-677 reliably increases GH and IGF-1 levels within the physiological range when taken at doses of 12.5-25mg. Multiple clinical trials have demonstrated its ability to increase lean body mass, improve bone mineral density, and enhance sleep quality (specifically slow-wave sleep). It has been studied in populations ranging from elderly adults with low GH to growth hormone-deficient children.
A key consideration is MK-677's ghrelin agonism, which substantially increases appetite—an effect useful for those in a caloric surplus but challenging for those using it primarily for fat loss. Water retention is also common, particularly in the first few weeks. Despite its technically non-peptide structure, MK-677 produces GH/IGF-1 effects functionally equivalent to injectable GH secretagogues.
Primary Benefits
GHRH analog that stimulates natural growth hormone release, clinically proven to reduce visceral adipose tissue
GHRH analog with extended half-life through DAC technology, providing sustained pulsatile GH release over days
Potent synthetic GH secretagogue producing stronger GH release than ipamorelin, with notable cardioprotective properties