What is MK-677?
An introduction to investigational MK-677 (ibutamoren/LUM-201), its growth-hormone effects, human trial limits, and current pediatric research.
What is MK-677?
MK-677, or ibutamoren, is an oral, non-peptide growth-hormone secretagogue. It is also called MK-0677 and is being studied as LUM-201. It acts at the ghrelin receptor and has raised growth hormone (GH) and insulin-like growth factor 1 (IGF-1) in human research. FDA says it is not approved; a hormone increase should not be mistaken for proven clinical benefit.
What has human research found?
In a randomized study of 65 healthy older adults, MK-677 raised GH/IGF-1 and fat-free mass over the one-year primary assessment. It did not significantly reduce abdominal visceral or total fat, and it detected no significant strength or function gain. Its size and duration were insufficient to evaluate functional endpoints, so that result does not rule out a functional effect. A separate eight-person dietary-restriction crossover study found improved nitrogen balance, a short-term laboratory measure rather than proof of clinical muscle preservation. In 24 obese men studied for eight weeks, fat-free mass rose but total and visceral fat did not significantly change; an oral glucose-tolerance test showed impaired glucose homeostasis.
The limits matter across indications. In a 161-person hip-fracture trial, IGF-1 increased without significant functional-performance improvement. A 563-person Alzheimer disease trial found higher IGF-1 but no significant slowing of clinical progression. Those studies do not support using MK-677 for general muscle growth, weight loss, cognitive health, or anti-aging.
Is development still active?
Yes. The OraGrowtH210 Phase 2 study is completed with posted registry results, and a Phase 3 LUM-201 trial in children with growth-hormone deficiency is recruiting in the registry checked in September 2026. Children in that program are different from the older adults and obese men in the studies above. Active development does not mean FDA approval, established effectiveness, or an appropriate treatment for other populations. The older statement that all MK-677 development was discontinued is outdated.
Safety and sport status
The older-adult trial reported increased fasting glucose, reduced insulin sensitivity, increased appetite, transient mild edema, and muscle pain. FDA warns of possible additional harms, including heart-failure risk in some individuals; it does not provide a trial incidence rate. WADA’s 2026 Prohibited List names ibutamoren (MK-677). This article summarizes research and is not medical or product-selection advice.
Sources & Citations
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Disclaimer: This article is for educational purposes only and does not constitute medical advice. The information presented is based on current research but should not be used for diagnosis, treatment, or prevention of any disease. Always consult a qualified healthcare provider before making health decisions.