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MK-677

Ibutamoren · Ibutamoren Mesylate · L-163191 · MK677

GH SecretagoguePhase II
From$0.07/mgCompare prices
MW
624.8g/mol
Formula
C28H40N4O8S2

MK-677, also known as ibutamoren, is a non-peptide growth hormone secretagogue that stimulates the release of growth hormone (GH) and insulin-like growth factor 1 (IGF-1) from the pituitary gland. Researchers primarily study MK-677 for its potential effects on muscle mass, body composition, and recovery from catabolic states, particularly in the context of sports medicine and aging. Key findings from studies indicate that MK-677 can reverse diet-induced nitrogen wasting and improve nitrogen balance in calorically restricted individuals, while also increasing circulating levels of IGF-1. However, concerns have been raised regarding its association with cardiovascular risks and metabolic dysfunction, highlighting the need for caution. Current research status reflects a growing interest in understanding both the therapeutic potential and safety profile of MK-677, although robust human clinical data remain limited.

Chemical Profile

Chemical Profile

Chemical structure
Chemical Structure
FormulaC28H40N4O8S2
Molecular Weight624.8 g/mol
CAS Number159752-10-0
PubChem CID6450830
ChEMBL IDCHEMBL4520674

Half-Life

INIntranasal

Not applicable

POOral

~4 to 6 hours

MK-677 is primarily administered orally due to its high bioavailability and prolonged effect on GH levels.

Mechanism

Mechanism of Action

MK-677 acts as a selective agonist of the growth hormone secretagogue receptor (GHSR), stimulating the release of growth hormone (GH) from the anterior pituitary gland via the GHSR-mediated signaling pathway. This activation leads to increased levels of insulin-like growth factor 1 (IGF-1) and enhanced nitrogen balance, promoting anabolic processes such as muscle growth and fat metabolism. The precise downstream signaling mechanisms remain to be fully elucidated, particularly regarding the interplay with other hormonal axes and metabolic pathways.

Research

32 Research Publications

1,984

Total Citations

20

Human/RCT

3.6

Avg. Influence

2025

Latest

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#01

Stimulation of the growth hormone (GH)-insulin-like growth factor I axis by daily oral administration of a GH secretogogue (MK-677) in healthy elderly subjects.

HumanInfluence14.0
278
Researchers observed that daily oral administration of MK-677 in healthy elderly subjects significantly increased GH and IGF-I concentrations, enhancing pulsatile GH release.
25 mgoral(human)7 days10 mgoral(human)4 days50 mgoral(human)4 days4 mg/kgoral(rat)6 weeks25 mgoral(human)8 weeks25 mgoral(human)8 weeks2 mgoral(human)14 days10 mgoral(human)2 weeks
PubMed
#02

Oxindole derivatives as orally active potent growth hormone secretagogues.

AnimalInfluence1.0
232
The study demonstrated that the oxindole derivative SM-130686 exhibited potent growth hormone releasing activity in cultured rat pituitary cells and showed significant in vivo effects with 28% oral bioavailability in rats.
25 mgoral(human)7 days10 mgoral(human)4 days50 mgoral(human)4 days4 mg/kgoral(rat)6 weeks25 mgoral(human)8 weeks25 mgoral(human)8 weeks2 mgoral(human)14 days10 mgoral(human)2 weeks
PubMed
#03

Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure.

HumanInfluence5.0
173
The study demonstrated that MK-677 significantly increased GH secretion and fat-free mass in obese males, suggesting its anabolic effects.
25 mgoral(human)7 days10 mgoral(human)4 days50 mgoral(human)4 days4 mg/kgoral(rat)6 weeks25 mgoral(human)8 weeks25 mgoral(human)8 weeks2 mgoral(human)14 days10 mgoral(human)2 weeks
PubMed
#04

Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial.

HumanInfluence4.0
164
The study demonstrated that MK-677 significantly increased fat-free mass and growth hormone secretion in healthy older adults without serious adverse effects over a two-year period.
25 mgoral(human)7 days10 mgoral(human)4 days50 mgoral(human)4 days4 mg/kgoral(rat)6 weeks25 mgoral(human)8 weeks25 mgoral(human)8 weeks2 mgoral(human)14 days10 mgoral(human)2 weeks
PubMed
#05

Nonpeptide and peptide growth hormone secretagogues act both as ghrelin receptor agonist and as positive or negative allosteric modulators of ghrelin signaling.

AnimalInfluence12.0
128
The study demonstrated that MK-677 acts as a ghrelin receptor agonist and modulates ghrelin signaling, highlighting its potential as a therapeutic agent.
25 mgoral(human)7 days10 mgoral(human)4 days50 mgoral(human)4 days4 mg/kgoral(rat)6 weeks25 mgoral(human)8 weeks25 mgoral(human)8 weeks2 mgoral(human)14 days10 mgoral(human)2 weeks
PubMed
#06

MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism.

Murphy M G, et al. · The Journal of clinical endocrinology and metabolism · 1998

HumanInfluence2.0
96
The study demonstrated that MK-677 significantly improved nitrogen balance in human participants during caloric restriction, indicating its potential to reverse diet-induced protein catabolism.

Key findings

  1. 01MK-677 improved nitrogen balance during caloric restriction, reversing diet-induced protein loss.
  2. 02Participants taking MK-677 had higher levels of insulin-like growth factor-I (IGF-I) compared to those on placebo.
  3. 03The study indicated that MK-677 was well tolerated with no significant adverse effects reported.
25 mgoral(human)7 days10 mgoral(human)4 days50 mgoral(human)4 days4 mg/kgoral(rat)6 weeks25 mgoral(human)8 weeks25 mgoral(human)8 weeks2 mgoral(human)14 days10 mgoral(human)2 weeks
PubMed
#07

Prolonged oral treatment with MK-677, a novel growth hormone secretagogue, improves sleep quality in man.

Human
92
Researchers observed that MK-677 improved sleep quality in both young and older adults, suggesting its potential effects on sleep regulation.
25 mgoral(human)7 days10 mgoral(human)4 days50 mgoral(human)4 days4 mg/kgoral(rat)6 weeks25 mgoral(human)8 weeks25 mgoral(human)8 weeks2 mgoral(human)14 days10 mgoral(human)2 weeks
PubMed
#08

Effect of alendronate and MK-677 (a growth hormone secretagogue), individually and in combination, on markers of bone turnover and bone mineral density in postmenopausal osteoporotic women.

HumanInfluence4.0
89
The study demonstrated that MK-677 combined with alendronate increased bone mineral density at the femoral neck compared to alendronate alone, while mitigating its suppressive effects on bone formation.
25 mgoral(human)7 days10 mgoral(human)4 days50 mgoral(human)4 days4 mg/kgoral(rat)6 weeks25 mgoral(human)8 weeks25 mgoral(human)8 weeks2 mgoral(human)14 days10 mgoral(human)2 weeks
PubMed
#09

Growth hormone-releasing hormone and growth hormone-releasing peptide as therapeutic agents to enhance growth hormone secretion in disease and aging.

ReviewInfluence1.0
82
The study demonstrated that MK-677 can stimulate GH secretion in GH-deficient children and adults, suggesting its therapeutic potential in addressing GH deficiency.
25 mgoral(human)7 days10 mgoral(human)4 days50 mgoral(human)4 days4 mg/kgoral(rat)6 weeks25 mgoral(human)8 weeks25 mgoral(human)8 weeks2 mgoral(human)14 days10 mgoral(human)2 weeks
PubMed
#10

Effects of a 7-day treatment with a novel, orally active, growth hormone (GH) secretagogue, MK-677, on 24-hour GH profiles, insulin-like growth factor I, and adrenocortical function in normal young men.

Human
80
Researchers observed that MK-677 increased GH pulse frequency and serum IGF-I levels in healthy young men without significantly altering cortisol profiles.
25 mgoral(human)7 days10 mgoral(human)4 days50 mgoral(human)4 days4 mg/kgoral(rat)6 weeks25 mgoral(human)8 weeks25 mgoral(human)8 weeks2 mgoral(human)14 days10 mgoral(human)2 weeks
PubMed
Safety

Safety & Handling

Research Gaps

Human clinical studies on MK-677 are limited and often lack robust controls or rigorous study designs, making it difficult to draw definitive conclusions about its efficacy and safety. Additionally, the long-term effects of MK-677 on metabolic health, cardiovascular function, and hormonal balance remain unclear, particularly in diverse populations outside the small sample sizes currently studied.

Solubility

MK-677 is soluble in DMSO and ethanol but has limited solubility in water.

Storage & Handling

Lyophilized

Stable for 2+ years at -20°C, 12 months at 4°C

Reconstituted

Use within 14 days when refrigerated at 4°C

Avoid

Avoid repeated freeze-thaw cycles, direct light

Solvent

Bacteriostatic water or sterile saline recommended

Safety information is derived from published research and may not reflect all known risks. This is not medical advice.

Legal Status

Legal Status

🇩🇪DE

Not approved as a medicinal product. Not a controlled substance. Sale as research chemical is a legal grey area.

🇺🇸US

Not approved by the FDA for any medical use. Not scheduled by the DEA.

🇦🇺AU

Not approved by the TGA. Considered a Schedule 4 substance, requiring prescription for therapeutic use.

🇬🇧UK

Not approved by the MHRA for medical use. Sale for research purposes only.

Legal status information is provided for general reference only and may not reflect the most current regulatory changes. Always verify with official government sources before making any decisions.

Community Insights

Community Insights

Publications per Year

31 total
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Pricing

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Top 5 of 19 offers from 13 vendors. Prices updated daily.

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Mechanism

Tools

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Mechanism

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Legal Disclaimer

This page is for informational and research purposes only. All information is based on published scientific literature and does not constitute medical advice, diagnosis, or treatment recommendations. Many substances listed may not be approved for human use and may be subject to drug regulation laws (e.g., AMG in Germany, FDA in the US). PepStack does not encourage the use of any substance on humans. Always consult a qualified healthcare professional before making any health-related decisions. Use of this information is entirely at your own risk. PepStack assumes no liability for the accuracy, completeness, or timeliness of the content provided. Full disclaimer