MK-677

MK-677, also called ibutamoren, MK-0677, and in current development LUM-201, is an oral small molecule rather than a peptide. A receptor-cloning experiment identified the pituitary/hypothalamic growth-hormone-secretagogue receptor pathway. Human experiments show increased GH secretion and circulating IGF-1 after MK-677, but a hormone response is not itself a treatment benefit (older-adult endocrine trial; GH-deficient adult study).

What human trials show

In a randomized study of 65 healthy older adults, fat-free mass increased over one year while the placebo group’s mean declined. The trial did not find significant improvement in abdominal visceral fat, total fat mass, strength, or function. Its duration and participant number were insufficient to evaluate functional endpoints, so the result cannot rule out a functional effect. It also reported increased fasting glucose, reduced insulin sensitivity, more appetite, transient mild lower-extremity edema, and muscle pain. Its second year was exploratory; this sample cannot establish long-term or rare-event safety. A separate 161-person post-hip-fracture trial found higher IGF-1 without statistically significant improvement in its functional-performance outcomes. A dietary-restriction crossover experiment in eight healthy volunteers measured improved nitrogen balance, not clinical recovery or durable muscle preservation. These populations and endpoints should not be summed as independent evidence of a sarcopenia treatment.

An 18-month randomized trial of 292 women with postmenopausal osteoporosis found a femoral-neck bone-density difference when MK-677 was added to alendronate, but no corresponding enhancement at the lumbar spine, total hip, or total body. Smaller studies measured bone-turnover markers rather than fracture prevention (24 obese men; pooled elderly-adult marker analysis). The pooled paper draws on three earlier trials; it is not another independent treatment cohort.

A sleep study reported stage-IV and REM changes in eight healthy young adults in a placebo-controlled crossover, plus observations in six older adults studied in a different sequence. A related nine-man endocrine crossover study measured GH/IGF-1 and cortisol profiles; it is not an independent proof of clinical sleep benefit, and participant overlap with the small sleep program is not established. Neither paper validates a general sleep-improvement claim or a predictable week-by-week user timeline.

For cognition, a 563-person randomized Alzheimer disease trial found higher IGF-1 but no significant slowing of clinical progression over 12 months. This directly limits claims that hormonal changes imply brain or anti-aging benefit. The publication’s randomized count and the related registry’s enrollment field differ; this page does not merge those values into a synthetic total.

Current development and limits

The older nine-man GH-deficiency experiment studied short-term hormonal responses, not adult replacement outcomes. A later 68-child analysis explored markers that predicted growth response in an earlier pediatric randomized trial; its children must not be counted again as participants in today’s OraGrowtH studies. The official registry lists a completed Phase 2 pediatric trial with posted results, a recruiting Phase 3 trial, and separate extension and pharmacokinetic studies. These records make the former blanket “development discontinued” statement false. They do not constitute FDA approval or establish routine use in any age group.

Other registrations include a completed twelve-person open-label fatty-liver pilot with posted results, a not-yet-recruiting LUM-201 plus semaglutide obesity study, and older renal, fibromyalgia, fracture, and Alzheimer studies. A registry’s status, planned enrollment, or posted-results flag is not itself a positive efficacy finding. The accompanying trials table uses study completion dates rather than primary-endpoint dates and marks estimates as such.

FDA states that ibutamoren is not approved and warns of appetite, water-retention, fatigue, muscle-pain, glucose-metabolism, and possible heart-failure risks; that warning does not supply an incidence rate. An FDA orphan designation for GH deficiency is explicitly not approval. WADA’s 2026 Prohibited List names ibutamoren (MK-677). This page summarizes research and is not treatment, dosing, or product-selection advice.

Selected primary-publication record

The 13 selected publications underlying the page’s count are linked here; the 14 trial registrations and regulatory records are separate. GH mechanism and endocrine studies: Howard 1996, Chapman 1996, Chapman 1997, Copinschi 1996, and Copinschi 1997. Body composition, function, and disease outcomes: Nass 2008, Bach 2004, Murphy 1998, and Sevigny 2008. Bone research: Svensson 1998, Murphy 1999, and Murphy 2001. Pediatric responder analysis: Bright 2021. These are publication records, not 13 independent randomized cohorts or proof of 13 clinical benefits.