● pepmg Research Desk · Peer-reviewed evidence review
What the research says about MK-677 (ibutamoren)
A neutral summary of the peer-reviewed literature on MK-677 (ibutamoren mesylate), an orally active growth-hormone secretagogue studied in multiple randomized human trials that raised IGF-1 but largely missed their clinical endpoints. Research use only.
Moderate evidence — Limited human trials — often early-phase. This describes the state of the published literature, not a claim that this compound works, is safe, or is for human use. Research use only.
The short version
- MK-677 (ibutamoren) is an orally active, non-peptide growth-hormone secretagogue: it activates the ghrelin/growth-hormone-secretagogue receptor to raise the body's own growth hormone and IGF-1, and it has been tested in several randomized, double-blind, placebo-controlled trials [1][7].
- The trials reliably raised IGF-1 (about 40% in one obesity study) and moved bone-turnover markers, but the larger outcome trials were mostly negative: MK-677 did not slow Alzheimer's progression in 563 patients and gave only a mixed functional signal after hip fracture [1][3][6][8].
- Reported and case-documented adverse effects include increased appetite, fluid retention (edema), muscle pain, and rare liver enzyme elevations; MK-677 is a banned substance in sport and has been found in adulterated supplements [4][5][9].
- This page reports what the studies measured. It is not medical advice, an efficacy or safety claim, or dosing guidance. Research use only.
What MK-677 is
MK-677, also written MK-0677 and sold as ibutamoren or ibutamoren mesylate, is described in the literature as an orally active, non-peptide (small-molecule) growth-hormone secretagogue. It mimics the hormone ghrelin at the growth-hormone-secretagogue receptor, promoting a pulsatile release of the body's own growth hormone that remains subject to normal negative feedback, and in turn raising insulin-like growth factor 1 (IGF-1) [7]. Unlike injected peptides in the same functional class, it is taken by mouth.
MK-677 is not an approved medicine. It was developed and studied as a clinical candidate for conditions linked to low growth hormone and has more recently appeared as an ingredient in performance-enhancing supplements, where it is a banned substance in sport [5][9]. Material sold by research-chemical vendors is not an approved pharmaceutical product and is offered for laboratory and research use only.
What the human research has measured
Moderate evidenceAcross randomized, double-blind, placebo-controlled studies, MK-677's most consistent effect is a rise in IGF-1. In healthy obese men treated for 8 weeks, serum IGF-1 increased approximately 40% versus placebo, alongside increases in growth hormone and IGF-binding protein-3 [1]. Companion analyses from that population reported that markers of bone formation rose (roughly a 23% and 28% increase in two procollagen markers within 2 weeks and a 15% rise in osteocalcin by 8 weeks), while an accompanying lipoprotein analysis found no significant change in total or LDL cholesterol [3][2]. A pooled analysis of elderly adults across three short controlled studies similarly reported increases in IGF-1 and bone-turnover markers [10].
The larger, outcome-focused trials were mostly negative. In a 12-month study of 563 patients with mild-to-moderate Alzheimer's disease, MK-677 raised IGF-1 but did not slow the rate of symptom progression on the pre-specified cognitive and clinical measures [6]. A randomized study in 123 elderly patients recovering from hip fracture reported a significant improvement in gait speed (a 0.7-point difference in means, p=0.011) but no significant change in stair-climbing power (p=0.292) or several other functional measures [8].
Taken together, these trials establish that oral MK-677 durably raises IGF-1 and shifts bone markers, but they did not demonstrate a clear clinical benefit on the disease endpoints they were designed to test.
What the trials and case reports say on safety and adverse events
Moderate evidenceA review of growth-hormone secretagogues notes that long-term studies of growth-hormone-raising therapy give conflicting results on safety, which is part of why the parent hormone is tightly regulated; the theoretical drawbacks are linked to raising IGF-1 and to impaired regulatory feedback [7]. The controlled MK-677 trials were designed around efficacy endpoints rather than large safety databases, but commonly described effects of this drug class include increased appetite and fluid retention.
Case reports document real-world harms. One describes an otherwise healthy man in his early 30s who developed liver-enzyme elevation (transaminitis) after taking MK-677 for 2 months, with liver tests returning to normal after he stopped; that report also lists edema, increased appetite, and muscle pain among known effects [4]. A separate case links contaminated performance-enhancing supplements, one containing MK-677 alongside a selective androgen receptor modulator and other banned agents, to bilateral gynecomastia and hypogonadotropic hypogonadism, underscoring that supplement products are frequently adulterated [9].
None of this is a safety guarantee or a prediction for any individual. Material sold by research-chemical vendors is not an approved pharmaceutical product, may be impure or mislabeled, and has not passed the controlled long-term safety evaluation an approved drug requires. This is not medical advice; consult a qualified professional and read the studies directly.
How strong is the evidence
The evidence base is characterized as moderate: MK-677 has been through multiple randomized, double-blind, placebo-controlled human trials, which is more controlled human data than most compounds in this library have [1][6][8]. What keeps it from a stronger characterization is the direction of those results: the trials reliably changed biomarkers (IGF-1, bone turnover) but the larger studies did not meet their clinical outcomes, and MK-677 is not an approved therapy [6][8]. "Moderate" describes the quantity and design of the trials, not a verdict that the compound works for any purpose.
Nothing here is dosing, medical, or safety guidance. Read the studies themselves and consult a qualified professional. This page is a map to the evidence, not a recommendation.
Sources · 10
- Two-month treatment of obese subjects with the oral growth hormone secretagogue MK-677 increases GH secretion and IGF-I.
- Treatment of obese subjects with the oral growth hormone secretagogue MK-677 affects serum lipoproteins.
- Treatment with the oral growth hormone secretagogue MK-677 increases markers of bone formation and resorption.
- Hepatotoxicity induced by MK-677.
- Chemical Composition and Labeling of Substances Marketed as Selective Androgen Receptor Modulators and Sold via the Internet.
- Growth hormone secretagogue MK-677: no clinical effect on AD progression in a randomized trial.
- The Safety and Efficacy of Growth Hormone Secretagogues.
- MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture.
- Reversible Gynecomastia and Hypogonadism Due to Usage of Commercial Performance-Enhancing Supplements.
- Oral administration of the growth hormone secretagogue MK-677 increases markers of bone turnover in healthy elderly subjects.
pepmg summarizes the peer-reviewed literature and links to every source — it sells nothing, ships nothing, and gives no medical, dosing, or human-use guidance. Don't just trust this summary: follow any citation to its source and read it yourself. Research use only.