MK-677 (Ibutamoren): FDA Status and Evidence
An oral growth hormone secretagogue that FDA lists in Category 2. It is not FDA-approved; the available research is limited and does not establish a longevity benefit.
Medically reviewed by Charles Kamen, MD, board-certified neurologist · ·
What the research shows
MK-677 is a small molecule, not a peptide. It mimics ghrelin and raises growth hormone and IGF-1 levels. In a 12-month trial in healthy older adults it increased lean mass, but fasting glucose rose and insulin sensitivity fell (Nass, Annals of Internal Medicine, 2008). No trial shows it improves strength, function or longevity outcomes.
Reported effects include increased appetite, fluid retention, muscle pain and higher blood sugar. It is on the World Anti-Doping Agency prohibited list.
Frequently Asked Questions
Is MK-677 FDA-approved?
No. MK-677 (ibutamoren) is not an FDA-approved drug for any use, and FDA lists ibutamoren mesylate in Category 2 for both 503A and 503B compounding.
What does Category 2 mean?
Category 2 is FDA's list of bulk drug substances that may present significant safety risks. Substances on it should not be used in compounding while that listing stands.
Is MK-677 a peptide?
No. It is an oral small molecule that acts on the ghrelin receptor. It is often sold alongside peptides, which causes the confusion.
Selected Research
Peer-reviewed sources on MK-677 (Ibutamoren). Research does not constitute a treatment recommendation; appropriateness is determined only after a medical evaluation.
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