MK-677, also known as Ibutamoren Mesylate, is an orally active growth hormone secretagogue and ghrelin receptor (GHS-R1a) agonist. Unlike peptide-based growth hormone secretagogues, MK-677 is a non-peptide small molecule that mimics the action of the hormone ghrelin by stimulating the ghrelin receptor.
Activation of the ghrelin receptor increases pulsatile secretion of growth hormone (GH) and subsequently increases circulating insulin-like growth factor-1 (IGF-1). Because it is orally bioavailable and has a relatively long half-life (approximately 24 hours), MK-677 has been investigated as a potential treatment for growth hormone deficiency, frailty in older adults, muscle wasting, osteoporosis, and other conditions associated with reduced GH secretion.
Despite extensive clinical investigation, MK-677 has never received FDA approval for any medical indication.
MK-677 selectively activates the growth hormone secretagogue receptor (GHS-R1a), commonly referred to as the ghrelin receptor.
Activation of this receptor may result in:
Unlike recombinant human growth hormone, MK-677 stimulates the body’s own endocrine system rather than supplying GH directly.
The GH/IGF-1 axis governs two primary biological functions: Somatic Growth and Metabolism.
Growth (Somatic & Linear)
Metabolism
Published clinical research suggests MK-677 may produce several physiologic effects.
Potential benefits may include:
Although these findings are promising, MK-677 has not been approved for any of these uses, and additional research is needed to establish long-term safety and efficacy.
Clinical studies have identified several potential adverse effects associated with MK-677.
Reported side effects include:
Because MK-677 stimulates the GH/IGF-1 axis, theoretical concerns exist regarding its use in individuals with active malignancy or conditions associated with excessive GH signaling.
Several clinical studies have demonstrated measurable reductions in insulin sensitivity during treatment, making careful monitoring important in patients with diabetes or prediabetes.
MK-677 should generally be avoided or used only with caution in individuals with:
Individuals with metabolic syndrome, obesity, or impaired glucose tolerance should undergo careful monitoring if treated because MK-677 may worsen insulin resistance.
MK-677 (Ibutamoren) is NOT FDA-approved for any medical indication in the United States.
It has not been approved for:
Although numerous clinical trials have been completed, no FDA-approved drug product containing MK-677 is currently available.
Human Studies
MK-677 has been evaluated in numerous human clinical trials involving healthy adults, elderly individuals, patients with hip fracture, obesity, growth hormone deficiency, and other conditions.
Human studies have demonstrated that MK-677:
A landmark randomized clinical trial published in the Annals of Internal Medicine demonstrated sustained increases in GH and IGF-1 with increases in fat-free mass among healthy older adults, although improvements in functional outcomes were limited.
Animal & Preclinical Studies
Animal studies have demonstrated that MK-677:
These studies established the biologic activity of MK-677 and supported progression into human clinical trials.
Human Studies
Review Articles
Regulatory Resources
The information provided on this page is intended for educational and informational purposes only. It is not intended to diagnose, treat, cure, or prevent any disease and should not be considered medical advice.
This content was generated with the assistance of artificial intelligence (AI) and reviewed for general accuracy; however, it may contain errors or omissions and should not replace professional medical judgment. Individuals should consult a qualified healthcare provider before beginning or changing any medical treatment.
MK677 is not FDA-approved for any medical indication in the United States. Its use remains investigational, and any clinical use may be considered off-label or non-approved depending on context. Individual results vary, and no specific outcome or benefit can be guaranteed. Patients should consult a qualified healthcare provider before beginning or changing any medical treatment.
R2 Medical Clinic uses medications sourced from compounding pharmacies. Compounded medications are not approved by the U.S. Food and Drug Administration (FDA). Unlike FDA-approved medications, compounded drugs have not undergone FDA review for safety, effectiveness, or efficacy through the FDA drug approval process. While 503B outsourcing facilities are registered with and inspected by the FDA and must comply with Current Good Manufacturing Practice (CGMP) requirements, the compounded medications they produce are not individually approved by the FDA. Similarly, compounded medications prepared by 503A pharmacies are not FDA-approved and are primarily regulated by state boards of pharmacy, with FDA oversight under applicable federal law.
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