Orally active non-peptide GH secretagogue. Only oral GHS-R1a agonist compound in widespread research. Sustained IGF-1 elevation with once-daily oral dosing makes it uniquely convenient in the GH secretagogue class.
4–6 hours; once-daily dosing sufficient due to downstream IGF-1 elevation persistence
SKUs
2
Evidence
Moderate Evidence
MK-677 (ibutamoren) is an orally active, non-peptide growth hormone secretagogue that activates the ghrelin receptor to stimulate GH and IGF-1 production. Unlike injectable GHRPs, it can be taken by mouth. It was extensively studied by Merck and others in clinical trials for growth hormone deficiency, muscle wasting, hip fracture recovery, and Alzheimer's disease. It is not FDA-approved but has substantial human clinical trial data.
Growth Hormone and IGF-1 Research
MK-677 reliably increases GH and IGF-1 levels with oral dosing. Phase 1 and 2 trials in healthy adults and GH-deficient patients confirmed its pharmacological activity and characterized dose-response relationships over days to months of treatment.
Body Composition Research
Clinical trials in older adults and people with GH deficiency showed MK-677 increased lean mass. A two-year trial in elderly men and women showed significant increases in lean body mass. Fat mass changes were less consistent.
Hip Fracture Recovery
A large multicenter trial examined MK-677 for recovery after hip fracture in elderly patients. Results did not show significant improvement in functional outcomes, though the trial found fewer serious falls in the MK-677 group.
Alzheimer's Disease Research
A phase 2 trial examined whether IGF-1 elevation from MK-677 could slow cognitive decline in Alzheimer's disease. The trial did not show benefit on cognitive endpoints despite successfully raising IGF-1 levels.
Oral dosing reliably raises GH and IGF-1 — well-characterized in human trials.
Increases lean body mass in older adults over months of treatment.
Did not improve functional outcomes in hip fracture recovery trial.
Did not slow cognitive decline in Alzheimer's disease trial despite IGF-1 elevation.
Meaningful side effect profile including increased appetite, fluid retention, and blood sugar effects.
MK-677 was studied extensively but failed to meet primary endpoints in its most ambitious trials (hip fracture, Alzheimer's). It increases appetite substantially through ghrelin receptor activation, which is a meaningful consideration in most use contexts. It raises fasting blood glucose and insulin levels with chronic use, which is relevant for metabolic health. It is not FDA-approved and development did not result in an approved product.
MK-677 is a small molecule that fits into and activates the ghrelin receptor. Because it is a small, stable, non-peptide molecule, it can survive the digestive process and be absorbed from the gut — something peptide GHRPs cannot do. Once absorbed, it activates ghrelin receptors in the pituitary and hypothalamus, triggering GH release. It also activates ghrelin receptors in hunger-control areas of the brain, which is why it consistently increases appetite. Because one dose lasts roughly 24 hours in the body, it provides sustained elevation of GH and IGF-1 over the dosing period rather than a sharp pulse, which creates a different hormonal pattern than injectable GHRP compounds.
Not FDA-approved. MK-677 increases fasting blood glucose and insulin levels, raising concerns about insulin resistance with long-term use. Fluid retention and increased appetite are common. Mild elevations in blood pressure have been reported. The hip fracture trial found more deaths in the MK-677 group (not statistically significant but notable). It stimulates cortisol slightly. People with diabetes, pre-diabetes, or metabolic risk factors should be particularly aware of the blood sugar implications.
Moderate Evidence
This compound has been studied in Phase 1 or Phase 2 human trials. Evidence is encouraging but more large-scale trials are needed.
Published Research Ranges
10–25mg/day oral in research; 25mg used in most published trials
Research Context Only: These are ranges reported in published scientific studies for educational reference. They are not dosing recommendations. This is not medical advice. Always consult a qualified healthcare professional.
Sources listed here are from the platform research library. All links open the original publication. No citations are generated by AI.
MK-677, an Orally Active Growth Hormone Secretagogue, Increases GH and IGF-1 Levels
Effect of alendronate and MK-677 (a growth hormone secretagogue), individually and in combination, on markers of bone turnover and bone mineral density in postmenopausal osteoporotic women
Treatment of obese subjects with the oral growth hormone secretagogue MK-677 affects serum concentrations of several lipoproteins, but not lipoprotein(a)
Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure
MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a multicenter, randomized, placebo-controlled phase IIb study
Research Education Only: This profile is for educational purposes only. All information is sourced from published scientific literature. This is not medical advice. Not for human consumption. Consult qualified medical professionals for any health decisions.
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