≥98%HPLC Purity
COAIncluded
USAShipped
MK-677 (Ibutamoren) Peptide
Selective, non-peptide ghrelin receptor agonist (GHS-R1a) that stimulates pulsatile growth hormone release without disrupting the natural GH secretion pattern. Orally bioavailable research compound for GH axis studies.
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Quick Facts
| SKU | MK677-001 |
|---|---|
| CAS Number | 159752-10-0 |
| Molecular Formula | C₂₇H₃₆N₄O₅S |
| Molecular Weight | 528.66 g/mol |
| Purity | ≥98% |
| Physical Form | Lyophilized Powder |
| Storage | Store at -20°C |
What is MK-677 (Ibutamoren)?
MK-677 (Ibutamoren Mesylate) is a potent, orally active, non-peptide ghrelin receptor agonist (growth hormone secretagogue receptor, GHS-R1a). Unlike peptide-based GH secretagogues such as GHRP-6 or Ipamorelin, MK-677 does not require injection and has excellent oral bioavailability with a half-life of approximately 24 hours.
It stimulates pulsatile growth hormone release while preserving the physiological GH secretion pattern, and has been shown to increase IGF-1 levels by 40-89% in clinical studies without significantly affecting cortisol levels.
Mechanism of Action
MK-677 mimics the endogenous ligand ghrelin by binding to the GHS-R1a receptor on anterior pituitary somatotrophs and hypothalamic neurons. This activates phospholipase C via Gq/11 signaling, increasing intracellular calcium and triggering GH vesicle exocytosis. Unlike exogenous GH, MK-677 preserves the natural pulsatile pattern of GH release, including the important nocturnal GH surge.
MK-677 also stimulates appetite via ghrelin receptor activation in the arcuate nucleus of the hypothalamus, and increases circulating IGF-1 through sustained GH elevation.
Research & Clinical Studies
MK-677 and Body Composition Research
A 2008 randomized controlled trial (Nass et al., Ann Intern Med) in healthy older adults found that MK-677 administration for 12 months increased GH and IGF-1 to young-adult levels, increased fat-free mass by 1.1 kg, and improved physical function measures without significant adverse effects.
A 1998 study (Murphy et al.) demonstrated that MK-677 reversed diet-induced protein catabolism, increasing nitrogen balance and lean body mass in calorie-restricted subjects within 7 days of administration.
[1] Nass R et al. Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults. Ann Intern Med. 2008;149(9):601-611. PubMed ↗
MK-677 and Sleep Quality Research
Research by Copinschi et al. (1997) found that MK-677 increased REM sleep duration by 50% and Stage IV (deep) sleep duration by 20% in healthy young subjects. The improvement in sleep architecture correlated with the nocturnal GH pulse amplification, suggesting MK-677 enhances the natural sleep-dependent GH secretory pattern.
[1] Copinschi G et al. Effects of a 7-day treatment with a novel, orally active, growth hormone (GH) secretagogue, MK-677, on 24-hour GH profiles. J Clin Endocrinol Metab. 1997;82(8):2590-7. PubMed ↗
MK-677 and Bone Density Research
Long-term MK-677 studies examined effects on bone mineral density. A 2-year randomized trial in elderly adults (Murphy et al., 2001) demonstrated that MK-677 increased markers of bone formation (osteocalcin) within 6 weeks and maintained elevated GH/IGF-1 for the full 2-year period. While BMD changes were modest at 12 months, analysis suggested the bone remodeling cycle requires 18-24 months for detectable density improvements.
[1] Murphy MG et al. 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. J Clin Endocrinol Metab. 2001;86(3):1116-1125. PubMed ↗
MK-677 and Nitrogen Balance/Catabolism Research
Murphy et al. (1998) demonstrated MK-677 reverses diet-induced catabolism within 7 days. In calorie-restricted volunteers (18 kcal/kg/day for 14 days), MK-677 administration restored nitrogen balance to positive values, indicating preservation of lean body mass despite caloric deficit. This anti-catabolic effect was dose-dependent and correlated with GH pulse amplitude increases.
[1] Murphy MG et al. MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism. J Clin Endocrinol Metab. 1998;83(2):320-325. PubMed ↗
Chemical & Physical Properties
MK-677 (Ibutamoren Mesylate) has a molecular weight of 624.77 g/mol and CAS number 159752-10-0. Molecular formula: C27H36N4O5S·CH4O3S. It is a white to off-white crystalline powder, soluble in DMSO and slightly soluble in water. Unlike peptide secretagogues, MK-677 is a small molecule with oral bioavailability.
Handling & Reconstitution
MK-677 is a non-peptide small molecule and does not require reconstitution with bacteriostatic water. It is typically supplied as lyophilized powder and can be dissolved in water, DMSO, or PEG-400 depending on the research protocol. For aqueous solutions, dissolve in sterile water at the desired concentration. MK-677 has moderate aqueous solubility at neutral pH.
Storage & Stability
Store MK-677 at room temperature (15-25C) in a cool, dry place away from light. For long-term storage, -20C is recommended. MK-677 is stable in powder form for up to 36 months when properly stored. Does not require reconstitution — it is typically administered as a powder or in solution form for research.
Frequently Asked Questions
Does MK-677 need to be refrigerated?
In powder form, MK-677 is stable at room temperature (15-25C) for extended periods. Refrigeration (-20C) is recommended for long-term storage beyond 6 months. Unlike peptides, MK-677 does not require reconstitution with bacteriostatic water.
Is MK-677 a peptide or a small molecule?
MK-677 is a non-peptide small molecule (MW 624.77 g/mol). It mimics ghrelin at the GHS-R1a receptor but is structurally distinct from peptide secretagogues like GHRP-6 or Ipamorelin. Its small molecule structure gives it oral bioavailability.
How does MK-677 compare to GHRP-6 and Ipamorelin?
MK-677 is orally active with a 24-hour half-life, while GHRP-6 and Ipamorelin require injection with half-lives of 15-30 minutes. MK-677 produces more sustained GH/IGF-1 elevation. GHRP-6 increases appetite more and Ipamorelin is more selective with fewer side effects.
What is the half-life of MK-677?
MK-677 has a terminal half-life of approximately 24 hours, allowing once-daily dosing in research protocols. Peak GH levels occur 1-2 hours post-administration, with sustained IGF-1 elevation for 24+ hours.
Does MK-677 affect cortisol?
Research shows MK-677 produces transient, modest cortisol increases that normalize within weeks of administration. The cortisol effect is significantly less than that seen with GHRP-6 or Hexarelin, making MK-677 preferred for long-term GH axis research.
Does MK-677 suppress natural GH production?
Research indicates MK-677 preserves the natural pulsatile GH pattern rather than creating continuous, non-physiological elevation. Unlike exogenous GH, MK-677 works through the ghrelin receptor, maintaining hypothalamic feedback regulation. Long-term studies (2 years) showed sustained GH/IGF-1 elevation without suppression.
What are common research observations with MK-677?
Published studies report: increased appetite (ghrelin receptor activation), water retention (GH-mediated), improved sleep quality (enhanced Stage IV sleep), elevated IGF-1 (40-89% increase), and transient increases in fasting blood glucose. Effects are dose-dependent and most pronounced in the first 2-4 weeks.
For laboratory and research use only. Not intended for human or animal consumption. All product information is derived from published preclinical research and does not constitute medical advice or claims.