MK-677
Last reviewed May 27, 2026
Also known as: Ibutamoren, Ibutamoren Mesylate, L-163,191, Nutrobal
Quick Answer
MK-677 is a gh secretagogue (oral) research compound (not FDA-approved for human use) studied for sustained gh/igf-1 elevation. MK-677 (Ibutamoren) is an orally bioavailable growth hormone secretagogue studied for sustainably elevating GH and IGF-1 levels over 24 hours with a single daily pill. Research dose: 12.50–12.50 mg 7x/wk. Half-life: 1 days. Available from COA-verified vendors with code PEPTIDEX for up to 20% off.
Where to Source
Ranked by $/mgSourcing data for MK-677 is updating.
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Where to Source
Ranked by $/mgSourcing data for MK-677 is updating.
We verify new listings weekly — check back soon.
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
Where to Buy MK-677
COA-verified vendors · Use code PEPTIDEX for up to 20% off
Verified pricing for MK-677 is not yet available in our database. Browse all COA-verified vendors on our price comparison tool, or check individual vendor pages.
Compare All Vendors§ Mechanism of Action
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.
§ Primary Benefits
- 1Sustained GH/IGF-1 elevation
- 2muscle growth
- 3improved sleep
- 4bone density
- 5oral dosing convenience
§ Clinical Evidence
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.
ModerateMK-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.
StrongMK-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.
ModerateMK-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.
ModerateMK-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.
ModerateMK-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.
ModerateOrally active growth hormone secretagogues: state of the art and clinical perspectives.
A study published in Annals of medicine investigating the effects and mechanisms.
ModerateGrowth hormone-releasing hormone and growth hormone-releasing peptide as therapeutic agents to enhance growth hormone secretion in disease and aging.
A study published in Recent progress in hormone research investigating the effects and mechanisms.
PreclinicalEffect 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.
A study published in The Journal of clinical endocrinology and metabolism investigating the effects and mechanisms.
PreclinicalGrowth hormone-releasing peptides and the cardiovascular system.
A study published in Annales d'endocrinologie investigating the effects and mechanisms.
Preclinical§ Safety 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.
See our evidence grading methodology for how we evaluate and grade peptide safety data.
§ Dosing Protocol
* Dosing data from published literature — not a human use recommendation.
RouteOral
Dose Range12500–12500 mcg
Frequency7x/wk
TimingPre-bed (optimizes sleep + GH surge)
Cycle Length12–12 weeks
BAC Water2.5 ml / 25mg vial
Standard dose: 10-25mg once daily. Oral capsule or liquid. Start at 10mg to assess appetite increase and glucose response. Pre-bed dosing leverages natural GH pulse. 5-on/2-off cycles used to manage appetite and insulin sensitivity.
§ Pharmacokinetics
⏱️ Half-Life: 1d
Plasma concentration over time§ Expected Outcomes
Week 1
Significant appetite increase; deeper sleep onset; vivid dreams; mild water retention
Weeks 2–4
Sustained IGF-1 elevation confirmed on bloodwork; improved recovery; skin quality improvement; morning puffiness from water retention
Month 2–3
Measurable fat-free mass increase (~1-2 lbs); improved bone turnover markers; hair/nail growth acceleration; monitor fasting glucose
Long-term
2-year clinical data shows sustained IGF-1 without tachyphylaxis; continued body composition benefits; requires ongoing glucose monitoring
§ Adverse Effects
| Side Effect | Incidence | Severity |
|---|---|---|
Increased appetite Most pronounced in first 2-4 weeks; often the dose-limiting factor | ~40-60% of users | moderate |
Water retention / bloating Mainly facial/periorbital puffiness; dose-dependent | ~30% of users | moderate |
Insulin resistance / elevated fasting glucose Monitor HbA1c and fasting glucose; more pronounced in obese/elderly | ~15-25% of users | moderate |
Lethargy / drowsiness Mitigated by pre-bed dosing | ~15% of users | mild |
Numbness / tingling (paresthesia) | ~8% of users | mild |
Joint pain Related to rapid GH/IGF-1 elevation; usually transient | ~5% of users | mild |
Where to Source MK-677 for Research
Finding verified, high-purity MK-677 requires rigorous COA verification. We independently evaluate vendors based on third-party HPLC testing, purity thresholds (≥98%), and batch-specific documentation.
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