MK-677
Also known as: Ibutamoren
Ghrelin Receptor Agonist | Oral Growth Hormone Secretagogue
Overview
Oral compound activating ghrelin receptors to trigger growth hormone release while preserving natural production. Achieves superior oral bioavailability exceeding 60% with a 24-hour half-life, making it unique among GH secretagogues for its convenient once-daily oral dosing.
Key benefits
- 97% increase in 24-hour growth hormone secretion
- 40-72% elevation in IGF-1 levels
- Enhanced sleep quality with improved REM patterns
- Preferential lean tissue gains of 1.1-2.7kg over 8-12 months
- 15% basal metabolic rate increase within 2 weeks
- Oral administration (no injections required)
Mechanism of action
Selectively binds GHS-R1a receptors in hypothalamus and pituitary, triggering pulsatile growth hormone release while maintaining natural circadian patterns.
Molecular data
- Type
- Non-peptide ghrelin receptor agonist
- Half-life
- ~24 hours
Indications
What the research community uses this compound for, with self-reported effectiveness.
Growth Hormone
GH Restoration
Most effectiveRestores youthful growth hormone levels in elderly subjects with 97% increase in 24-hour secretion.
IGF-1 Enhancement
Most effectiveSustained 40-72% IGF-1 elevation over extended periods.
Sleep Enhancement
Effective20% REM increase in younger adults; 50% improvement in elderly.
Body Composition
Muscle Preservation
Most effectiveDemonstrates +2.69g/day nitrogen retention versus -8.97g/day placebo, protecting lean mass during caloric restriction.
Fat-Free Mass
EffectiveIncreases fat-free mass with preferential lean tissue accrual.
Metabolic Rate
Effective15% basal metabolic rate elevation documented at 2 weeks.
Bone Health
Bone Formation
Effective39-45% increase in bone formation markers within 6-8 weeks.
Dosing protocols
Common protocols by delivery method. Adjust the curve below to model accumulation in your own cycle.
Oral
Optimal bioavailability eliminates injection requirements with convenient daily dosing. Take at bedtime on empty stomach for best results.
| Protocol | Dose | Frequency | Route / duration |
|---|---|---|---|
| Body composition/anti-aging | 25mg | 1x daily | Oral (bedtime, empty stomach) |
| Sleep quality improvement | 25mg | 1x nightly | Oral (30 minutes before bed) |
| Conservative initiation | 12.5mg | 1x daily | Oral (assess tolerance) |
Interactions
Pairwise interactions with other compounds you might be cycling — the same data behind the cycle builder's safety check.
HGH
AvoidRedundant effects without proportional benefits.
Insulin
MonitorMK-677 decreases insulin sensitivity; requires blood glucose monitoring.
LGD-4033
MonitorCase report documents 85.7% testosterone suppression and significant liver enzyme elevation when combined.
CJC-1295
SynergisticComplementary GH pathways providing combined pulsatile and baseline elevation.
Ipamorelin
SynergisticBoth stimulate GH release through different mechanisms.
GHRP-2
SynergisticMK-677 baseline elevation combines with GHRP-2 pulsatile spikes.
TB-500
CompatibleNon-competing mechanisms enhancing recovery effects.
BPC-157
CompatibleSystemic growth factors complement localized healing.
Timeline
Typical week-by-week effects reported in clinical and observational data.
- Week 1-2
Improved sleep quality, vivid dreams, possible appetite increase
- Week 2-4
Enhanced recovery, better sleep architecture, initial body composition changes
- Week 4-8
Noticeable lean mass gains, continued sleep benefits
- Week 8-12
Maximum body composition improvements, sustained GH elevation
Safety
Reported adverse effects, contraindications, and what to monitor on cycle.
Common side effects
- Appetite stimulation (>50% of users)
- Water retention (30-40%)
- Lethargy (20-30%)
- Fasting glucose elevation (5-15mg/dL)
- Note on testosterone suppression: at doses up to 20 mg daily, MK-677 is unlikely to cause significant testosterone suppression on its own. Above 20 mg daily, the likelihood of suppression and other side effects (insulin resistance, water retention, lethargy) increases. The case report documenting 85.7% testosterone suppression involved co-administration with LGD-4033, a SARM known to be profoundly suppressive, making the SARM the likely primary driver of that suppression.
Stop signs — stop and seek advice
- Shortness of breath, chest pain, or unusual fatigue
- Blood glucose levels >100mg/dL or diabetes symptoms
- Liver enzyme elevation (ALT/AST >2x upper normal)
- Severe fluid retention or unexplained swelling
- Any concerning cardiovascular symptoms
Contraindications
- Heart disease or congestive heart failure
- Diabetes or pre-diabetes
- Active cancer
- Severe cardiovascular disease
- Pregnancy or breastfeeding
Monitoring
- Blood glucose and HbA1c
- Liver function tests
- IGF-1 levels
- Blood pressure
Quality checks
What a legitimate product looks like, what should give pause, and what should make you stop.
Good signs
- Pharmaceutical-grade capsules with professional labeling
- Batch numbers and expiration dates
- Third-party testing documentation
- Certificate of analysis showing >98% purity
Warning signs
- Products labeled 'for research only' may lack quality control
Stop signs — don't use
- Dietary supplement claims (FDA prohibits MK-677 in supplements)
- Unknown purity or source without certificates of analysis
- Unusually low prices suggesting counterfeit product
Recent research
Newer papers and trial readouts on file for this compound, with source and date.
July 2024 · DEA Get Smart About Drugs
FDA Warning: Potential Health Risks of MK-677
Official communication highlighting significant cardiovascular risks and investigational drug status.
October 2022 · Physiological Reports
LGD-4033 and MK-677 use impacts body composition, circulating biomarkers, and skeletal muscle androgenic hormone and receptor content: A case report
Case report documenting that co-administration of LGD-4033 and MK-677 increased body mass and lean mass but negatively impacted serum lipids, liver enzymes, and testosterone levels (85.7% suppression when combined with the SARM).
July 2025 · BMJ Case Reports
Hepatotoxicity induced by MK-677
Case report of a man in his early 30s who developed transaminitis after 2 months of MK-677 use. Liver function returned to normal after discontinuation, highlighting the need for liver monitoring during use.
References
Primary literature and clinical-trial data informing this entry.
Effects of a 7-day treatment with a novel, orally active, growth hormone (GH) secretagogue, MK-677, on 24-hour GH profiles, insulin-like growth factor I, and adrenocortical function in normal young men
Copinschi, G., et al. · Journal of Clinical Endocrinology & Metabolism · 1996
Randomized, double-blind crossover in 9 healthy young men. 7-day oral MK-677 (5 and 25mg) increased 24-hour GH profiles dose-dependently while preserving circadian patterns.
Stimulation of the growth hormone (GH)-insulin-like growth factor I axis by daily oral administration of a GH secretagogue (MK-677) in healthy elderly subjects
Chapman, I.M., et al. · Journal of Clinical Endocrinology & Metabolism · 1996
Randomized, double-blind trial in 32 elderly subjects (64-81 years). 25mg/day MK-677 for up to 4 weeks increased mean 24-hour GH by 97% and restored IGF-I concentrations to young adult levels.
Prolonged oral treatment with MK-677, a novel growth hormone secretagogue, improves sleep quality in man
Copinschi, G., et al. · Neuroendocrinology · 1997
In young adults, 25mg MK-677 increased stage IV sleep duration by 50% and REM sleep by 20%. In older adults, REM sleep increased nearly 50% with decreased REM latency. Sleep deviations dropped from 42% to 8%.
MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism
Murphy, M.G., et al. · Journal of Clinical Endocrinology & Metabolism · 1998
Double-blind crossover in 8 healthy volunteers under caloric restriction. 25mg/day MK-677 for 7 days reversed nitrogen wasting (+2.69g/day vs -8.97g/day placebo) and significantly increased IGF-I.
Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure
Chapman, I.M., et al. · Journal of Clinical Endocrinology & Metabolism · 1998
24 obese males treated with 25mg/day for 8 weeks showed sustained increases in GH, IGF-I, fat-free mass, and a transient increase in basal metabolic rate at 2 weeks.
Oral administration of the growth hormone secretagogue MK-677 increases markers of bone turnover in healthy and functionally impaired elderly adults
Murphy, M.G., et al. · Journal of Bone and Mineral Research · 1999
187 elderly adults (65+) across three placebo-controlled studies. 9 weeks of MK-677 increased serum osteocalcin by 29.4%, bone-specific alkaline phosphatase by 10.4%, and urinary NTX by 22.6%.
Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial
Nass, R., et al. · Annals of Internal Medicine · 2008
12-month RCT in 65 healthy adults (60-81 years). MK-677 increased GH and IGF-I to young adult levels, increased fat-free mass while placebo group declined, and was generally well tolerated.
Last updated . How this page was sourced is described in the methodology.