What is MK-677?

What is MK-677?

MK-677 (ibutamoren) is a small molecule that stimulates growth hormone release by mimicking the hormone ghrelin. Unlike most peptides, it’s orally active, meaning it can be taken as a pill rather than injected. It is not FDA-approved for any use.

Key Facts

Fact	Detail
FDA Approved	No
Type	Non-peptide GH secretagogue
Administration	Oral
WADA Status	Prohibited

How Does It Work?

MK-677 activates the ghrelin receptor (GHSR) in the brain, which signals the pituitary gland to release growth hormone. Because it mimics ghrelin, it also increases appetite—a common side effect reported in studies.

Unlike injected growth hormone, MK-677 works through the body’s natural feedback mechanisms, causing pulsatile GH release rather than constant elevation.

Research Status

What Studies Show

• Several Phase II trials were conducted in elderly populations
• Studies showed consistent GH and IGF-1 increases
• A 2-year study in elderly adults found no significant improvement in functional outcomes
• Development was discontinued; no Phase III trials completed

Evidence Level

The compound has more human data than many research peptides, but clinical development was abandoned. The longest published study (2 years) did not demonstrate meaningful functional benefits despite raising GH levels.

Known Concerns

• Water retention and increased appetite are common
• May worsen insulin sensitivity with prolonged use
• Long-term effects are not established
• Products sold online are unregulated

Important Warnings

• Not approved for medical use anywhere
• Available only from unregulated sources
• Banned in competitive sports
• May affect blood glucose levels

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This guide is for educational purposes only. MK-677 is not approved by any regulatory agency.