Overview
MK-677 is classified as a gh secretagogue (oral) peptide. Sustained GH/IGF-1 elevation, muscle growth, improved sleep, bone density, oral dosing convenience.
Non-peptide ghrelin receptor (GHSR1a) agonist that stimulates prolonged, pulsatile growth hormone release from the pituitary gland. Unlike injectable GH peptides, MK-677 is orally bioavailable with a ~24-hour half-life, enabling once-daily dosing. Increases IGF-1 levels for up to 12 months without desensitization of the GH axis. Does not suppress natural GH secretion patterns or affect cortisol levels at standard doses.
Also known as: Ibutamoren, Ibutamoren Mesylate, L-163,191, Nutrobal
Category
GH Secretagogue (Oral)
Half-Life
24h
Route
Oral
FDA Status
Not Approved
How Does MK-677 Work?
Non-peptide ghrelin receptor (GHSR1a) agonist that stimulates prolonged, pulsatile growth hormone release from the pituitary gland. Unlike injectable GH peptides, MK-677 is orally bioavailable with a ~24-hour half-life, enabling once-daily dosing. Increases IGF-1 levels for up to 12 months without desensitization of the GH axis. Does not suppress natural GH secretion patterns or affect cortisol levels at standard doses.
At the molecular level, MK-677 operates through pathways characteristic of the GH Secretagogue (Oral) class, interacting with target receptors and downstream signaling cascades to produce its observed effects.
Published Research
The following studies are indexed from PubMed and peer-reviewed journals:
[1]MK-677 increases GH and IGF-1 without altering cortisol in healthy elderly
Chapman et al. (J. Clin. Endocrinol. Metab.): 25mg daily MK-677 for 2 weeks in healthy elderly subjects restored IGF-1 and GH profiles to young adult levels without altering cortisol, prolactin, insulin, or thyroid hormones.
Evidence: moderate[2]MK-677 2-year study: sustained IGF-1 elevation and body composition effects
Nass et al. (J. Clin. Endocrinol. Metab.): 2-year RCT in 65 healthy elderly adults. 25mg/day MK-677 increased GH and IGF-1 to young adult levels, increased fat-free mass by ~1.1kg, and did not affect BMD. Notable: fasting glucose increased by ~0.3 mmol/L.
Evidence: strong[3]MK-677 increases fat-free mass in healthy obese males
Svensson et al. (J. Clin. Endocrinol. Metab.): 8-week RCT in obese males. 25mg/day MK-677 significantly increased GH secretion, IGF-1, and fat-free mass. Transient increase in appetite and mild insulin resistance noted.
Evidence: moderate[4]MK-677 reverses diet-induced nitrogen wasting
Murphy et al. (J. Clin. Endocrinol. Metab.): MK-677 reversed diet-induced nitrogen wasting in healthy young volunteers on caloric restriction, demonstrating potent anti-catabolic properties.
Evidence: moderate[5]MK-677 improves sleep quality in healthy young and elderly
Copinschi et al. (Neuroendocrinology): MK-677 increased duration of stage IV (deep) sleep by 50% and REM sleep by 20% in both young and older subjects, correlating with enhanced overnight GH secretion.
Evidence: moderate[6]MK-677 increases bone turnover markers in postmenopausal women
Murphy et al. (J. Clin. Endocrinol. Metab.): 12-month study in postmenopausal women showing MK-677 (25mg/day) increased osteocalcin and bone-specific alkaline phosphatase, suggesting improved bone formation.
Evidence: moderateSafety Profile
Oral GH secretagogue with extensive clinical data (2+ year RCTs). Key concern: impairs insulin sensitivity and raises fasting glucose, especially in elderly/obese populations. One hip fracture trial in elderly was stopped early due to CHF signals. WADA prohibited. Not FDA-approved. Use caution in pre-diabetic or insulin-resistant individuals.
| Side Effect | Incidence | Severity |
|---|---|---|
| Increased appetite | ~40-60% of users | moderate |
| Water retention / bloating | ~30% of users | moderate |
| Insulin resistance / elevated fasting glucose | ~15-25% of users | moderate |
| Lethargy / drowsiness | ~15% of users | mild |
| Numbness / tingling (paresthesia) | ~8% of users | mild |
| Joint pain | ~5% of users | mild |
Sourcing MK-677 for Research
If you're looking to source MK-677 for laboratory research, our vendor directory compares pricing, purity testing, and COA verification from independently vetted suppliers.
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Full Research Profile
MK-677 — dosing, interactions, timelines & more
Comprehensive compound profile with sourcing information, stacking synergies, and outcome timelines.