MK-677 Reference

Plain English

What it is

MK-677, also called ibutamoren, is a lab-made pill that nudges the body to release more of its own growth hormone and a linked growth signal called IGF-1. It is a small molecule, not a peptide, and not a hormone replacement. It is not approved by the FDA for any use; the maker tested it in people for years and then stopped its development.

What people use it for

It is the rare compound in this group that is taken by mouth instead of by injection, which is its main draw. People reach for it hoping for deeper sleep, higher IGF-1, more appetite, and gains in lean body mass.

What the science shows

Unlike most research compounds, MK-677 has real multi-year human trials in older adults. Those studies confirmed it raises growth hormone and IGF-1 and can add lean mass, but the gains did not turn into a clear health benefit, which is part of why it was never approved.

The catch

The same trials kept finding fluid buildup and swelling, higher fasting blood sugar, and lower insulin sensitivity. One study in elderly hip-fracture patients was stopped early over a heart-failure safety signal. It is also banned in sports by the World Anti-Doping Agency.

Reference summary

Multiple multi-year human trials in elderly sarcopenia and osteoporosis populations documented sustained increases in GH and IGF-1 with oral MK-677. Clinical benefit on lean mass and bone turnover was limited, and fluid retention and fasting glucose increases were consistent findings. No FDA approval followed.

Regulatory and posture

Categories

GH Release

Aliases

Ibutamoren, Ibutamoren mesylate, MK-0677, L-163,191, Oral ghrelin receptor agonist (non-peptide)

Evidence posture

human - Large human trials exist, but development was discontinued. Water retention and raised fasting glucose are consistently reported; a congestive-heart-failure signal was reported in one elderly hip-fracture trial.

Regulatory status

Investigational non-peptide ghrelin-receptor agonist. Merck discontinued development after trials for sarcopenia and osteoporosis did not reach approval. There is no FDA-approved MK-677 drug label. MK-677 is an orally active small molecule, not a peptide, but is commonly grouped with peptide GH secretagogues. A September 18, 2024 FDA Federal Register notice (document 2024-21241) listed ibutamoren mesylate among bulk drug substances the Pharmacy Compounding Advisory Committee considered for inclusion on the section 503A Bulks List; this nomination review is not an approval, and MK-677 remains not FDA-approved.

Content review status

research reference

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