What it is
MK-677, also called ibutamoren, is an oral drug that copies the action of ghrelin. It is not actually a peptide, but it is often grouped with peptides because it raises growth hormone and IGF-1.
It was developed by Merck as a pill that could boost growth hormone without injections. It also increases appetite.
US regulatory status
Not FDA-approved. The FDA lists ibutamoren among bulk substances that may present significant safety risks in compounding (Category 2) and has sent warning letters to companies selling it in products marketed as supplements.
What the research shows
Human trials showed MK-677 raised growth hormone and IGF-1 and increased lean mass in some groups, but they did not show clear gains in strength or function. Studies also found increased appetite, fluid retention and worse blood sugar control, and a trial in older adults after hip fracture raised concern about heart failure.
How it is given
Oral capsule or liquid (unapproved)
Commonly reported side effects
- Increased appetite
- Water retention and swelling
- Higher blood sugar and insulin resistance
- Joint or muscle pain
- Tingling in hands (carpal tunnel-like symptoms)
- Tiredness
Questions to ask your provider
- Could MK-677 affect my blood sugar or heart?
- What would testing for growth hormone problems look like for me?
- Are supplements that contain ibutamoren legal and safe?