What MK-677 is
MK-677, or ibutamoren, is a small molecule taken by mouth. It acts on the ghrelin receptor, like ipamorelin, to raise growth hormone and IGF-1. It is not a peptide, but because it does the same job as several growth hormone peptides, it gets sold alongside them.
It was developed by Merck in the 1990s and tested in several human trials. It never became an approved drug. It's often marketed with SARMs as a "research chemical" or supplement.
Regulatory status in 2026
MK-677 is not an approved drug, cannot be legally sold as a supplement, and is not on the compounding list.
Merck develops MK-677 and tests it in human trials.
FDA's Pharmacy Compounding Advisory Committee votes against adding ibutamoren to the compounding list.
Not approved and not compoundable. Prohibited in sport at all times under WADA class S2 as a growth hormone secretagogue.
Regulatory status can change. Check the sources linked at the bottom of this page before relying on anything here.
Claims vs. what the research shows
MK-677 has more human data than most items in this library. The data shows it changes hormone levels. It also shows side effects.
Raises growth hormone and IGF-1.
Shown in multiple human trials. This is well supported.
Strong human evidenceBuilds muscle.
Trials showed increases in lean mass in some groups but not clear gains in strength or function.
Animal or limited evidenceImproves sleep.
A small early study reported changes in sleep stages. Not established.
Insufficient dataStorage and stability
MK-677 is sold as capsules or a liquid. Research-chemical products rarely list a validated shelf life.
Capsules and tablets
- Store capsules or tablets in a cool, dry place in a sealed container.
- Keep away from heat and humidity, such as a bathroom cabinet.
- Follow any storage directions on the label.
Liquids
- Liquids sold as research chemicals often have no stated shelf life. Treat their stability as unknown.
- Refrigerate liquids only if the label says to.
- Log the open date so you know how long you've had it.
Light exposure is easy to overlook in a fridge door that opens dozens of times a day. VIALTIGHT is building stackable cases that block light from every side. See vialtight.com for updates.
Safety flags
Heart failure signal. A trial in older adults recovering from hip fracture was stopped early after more cases of congestive heart failure occurred in the MK-677 group.
Blood sugar. It can raise blood sugar and reduce insulin sensitivity, which matters for anyone with or at risk of diabetes.
Common side effects. Increased appetite, water retention and swelling, and joint or muscle pain are commonly reported.
Tested athletes. Prohibited at all times under WADA class S2.
FAQ
Is MK-677 a peptide?
No. It's a small-molecule drug taken by mouth. It acts on the same receptor as some growth hormone peptides.
Is MK-677 a SARM?
No. It's often sold alongside SARMs, but it works on growth hormone, not androgen receptors.
Is it legal to buy?
It cannot be legally sold as a supplement or for human use. Products labeled "research only" don't change that.
Does VialTracker tell me what to take?
No. VialTracker organizes the information you enter and runs the math. It does not recommend doses, products, or protocols.