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
Body Composition
Bone Health
Dosing protocols
Common protocols by delivery method. Adjust the curve below to model accumulation in your own cycle.
Delivery method
| Protocol | Dose | Frequency | Duration |
|---|---|---|---|
| — | 25mg | 1x daily | — |
| — | 25mg | 1x nightly | — |
| — | 12.5mg | 1x daily | — |
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.
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
References
Primary literature and clinical-trial data informing this entry.