MK-677 (Ibutamoren) (Ibutamoren Mesylate (MK-677))
An orally active non-peptide GH secretagogue that mimics ghrelin signaling. Increases GH and IGF-1 for 24 hours from a single oral dose.
How it works
Acts as ghrelin mimetic at GHS-R1a receptors in hypothalamus and pituitary. Excellent oral bioavailability and 24-hour duration.
Key facts
- Molecular weight: 528.7 Da
- Half-life: 24 hours
- Bioavailability: High (oral)
- Storage: Room temperature, protected from light.
Dosing overview
- Typical dose: 10-25 mg
- Frequency: Once daily
- Duration: 12-24 week cycles
- Route: Oral (capsule/liquid)
Protocol notes
- Most start at 10 mg/day and assess for water retention and hunger before going to 25 mg.
- Taken as a single daily oral dose - no injecting and no fasting requirement.
- Often run in 3-6 month blocks because benefits (sleep, recovery, appetite) build over time.
Reported benefits
- Oral administration
- Sustained 24h GH elevation
- Increased IGF-1
- Improved sleep depth
- Enhanced recovery
- Bone density support
Possible side effects
- Increased appetite
- Water retention/edema
- Insulin resistance (long-term)
- Lethargy
- Joint pain
- Numbness
Research
- Two-year MK-677 treatment in elderly (2008): Reversed diet-induced nitrogen wasting, increased lean mass by 1.5kg, and elevated IGF-1 to young-adult levels.
- Effects of ibutamoren on bone mineral density (2019): 12 months increased BMD at femoral neck by 3.2% with sustained IGF-1 elevation.
Compare MK-677 (Ibutamoren)
Research and educational reference only. Not medical advice.