MK-677 (Ibutamoren) is a non-peptide, orally active small molecule that acts as a potent agonist of the growth hormone secretagogue receptor (GHS-R1a), the receptor for endogenous ghrelin. Unlike the peptide secretagogues in the GHRP family, MK-677 is a spiropiperidine-based synthetic compound designed for oral bioavailability and metabolic stability, mimicking the GH-stimulating action of ghrelin while resisting the enzymatic degradation that limits peptide agonists.
In research model systems, MK-677 stimulates pulsatile GH release and produces sustained elevations of GH and IGF-1 without markedly affecting cortisol, and it is characterized by a long functional half-life supporting once-daily oral administration in study protocols. It is supplied here as oral capsules containing ibutamoren for laboratory research only, and is not a peptide.
Research use only — not for human or animal consumption. Per-batch documentation is provided with the material.
Research on MK-677 has established it as a potent, orally active ghrelin-receptor agonist that produces dose-dependent, sustained increases in circulating GH and IGF-1 in model systems and clinical study populations, generally without meaningful elevation of cortisol. Its non-peptide structure confers oral bioavailability and a long duration of action relative to peptide secretagogues.
Longer-term studies have examined its effects on the GH/IGF-1 axis and on metabolic and body-composition endpoints; reported observations in study populations include increases in IGF-1 and fluid retention, underscoring its utility as a well-characterized oral secretagogue tool compound.
MK-677 (ibutamoren, originally L-163,191) was developed by Merck in the 1990s as an orally active, non-peptide growth hormone secretagogue derived from earlier GHS peptide pharmacophores. Extensively studied in clinical research on the GH/IGF-1 axis, it never received marketing approval and remains a widely used reference compound in secretagogue research.
View compound profile on NIH PubChem →
Cited literature refers to laboratory and preclinical research. MK-677 Capsules is supplied strictly for research use only and is not intended to diagnose, treat, cure, or prevent any disease.
