Product Details: MK-677 Ibutamoren Capsules
What is MK-677 (Ibutamoren)?
MK-677 Ibutamoren Capsules contain a synthetic non-peptide small molecule. It is classified as a selective, orally active agonist of the growth hormone secretagogue receptor subtype 1a (GHSR-1a). Researchers also refer to it by the developmental codes MK-0677 and L-163,191.
MK-677 is not a peptide. Its sulfonamide backbone allows oral bioavailability in preclinical settings. It is a structural characteristic that distinguishes it from peptide-based secretagogues that are degraded in the gastrointestinal tract.
ATTENTION: This product is strictly for LABORATORY AND RESEARCH PURPOSES ONLY. Not for human or veterinary use.
Mechanism of Action of MK-677 Ibutamoren Capsules
How Does MK-677 Interact with GHSR-1a?
MK-677 is a selective GHSR-1a agonist. It binds to the ghrelin receptor in the hypothalamus and pituitary gland, initiating a downstream signaling cascade that drives somatotropic axis activity in experimental models.
High-resolution cryo-EM structural studies have characterized the molecular basis of MK-677’s binding to GHSR-1a. This reveals a defined agonist-binding pocket, a salt bridge, and an aromatic cluster as key structural motifs in receptor activation. This interaction stabilizes the GHSR-Gᵢ signaling complex and initiates intracellular signal transduction.
Key mechanistic observations from laboratory studies:
- Gαq/11 signaling activation: MK-677 binding to GHSR-1a activates Gαq/11-coupled intracellular pathways. This leads to upregulation of somatotropic-axis–associated peptide signaling in experimental models
- GH pulse stimulation: In preclinical models, GHSR-1a activation by MK-677 is associated with pulsatile GH release from the anterior pituitary. The pulsatile pattern mirrors that of endogenous GH secretion.
- IGF-1 pathway engagement: Rodent model studies have examined somatostatin mRNA expression, GHSR mRNA levels, and somatotropic axis feedback under MK-677 administration — providing a mechanistic framework for investigating GH-IGF-1 axis dynamics
- Somatostatin counterregulation: In prolonged rodent administration studies, increases in hypothalamic SST mRNA expression were observed alongside decreased SSTR-2 expression in the pituitary. This indicates active neuroendocrine counterregulatory responses in the experimental model.
- Androgen receptor independence: MK-677 is thought to exhibit no significant affinity for androgen receptor pathways. This distinguishes it from SARMs and supports its use as a selective GHSR-1a probe in research designs requiring separation of androgenic and somatotropic signaling
Properties of MK-677 Ibutamoren Capsules
| Property | Detail |
| Molecular Formula | C₂₇H₃₆N₄O₅S |
| IUPAC Name | 2-amino-2-methyl-N-[1-(1-methylsulfonylspiro[2H-indole-3,4′-piperidine]-1′-yl)-1-oxo-3-phenylmethoxypropan-2-yl]propanamide |
| Synonyms | Ibutamoren, MK-0677, L-163,191, CHEMBL13817, Oratrope |
| Molecular Weight | 528.67 g/mol |
| CAS number | 159634-47-6 |
| PubChem CID | 9829523 |
| Purity | ≥99% (HPLC verified, per batch COA) |
| Physical Form | White lyophilized powder |
| Storage | −20°C, protected from light and moisture |
| Form | Free base (not mesylate salt) |
| Classification | Research Use Only (RUO) |
Research Applications of MK-677 Ibutamoren Capsules
MK-677 Ibutamoren Capsules are studied across several experimental research domains.
- GHSR-1a Receptor Signaling Studies
MK-677’s high selectivity and oral bioavailability make it a useful molecular tool for investigating GHSR-1a receptor binding dynamics, Gαq/11-coupled signal transduction, and downstream somatotropic pathway activation. Cryo-EM structural data reveal the molecular framework for GHSR signaling and provide a basis for developing new GHSR agonist research tools.
- Somatotropic Axis Research
In preclinical models, MK-677 has been studied for its ability to stimulate pulsatile GH release from the anterior pituitary via GHSR-1a activation. This makes it a relevant research tool for investigating GH-IGF-1 axis dynamics, including neuroendocrine feedback mechanisms involving somatostatin and GHRH in rodent and in vitro models.
- Neuroendocrine Feedback Mechanism Analysis
Laboratory studies in rats have examined SST mRNA upregulation and SSTR-2 receptor expression changes following MK-677 administration, providing a model for studying compensatory neuroendocrine feedback in the somatotropic axis.
- Metabolic Substrate and Signaling Pathway Research
MK-677 has been examined in preclinical metabolic models for its apparent influence on glucose-related and lipid-associated molecular pathways downstream of IGF-1 pathway activation. Findings in this area remain limited, and data across experimental systems are not fully consistent.
Risk and Handling Precautions
Risk Tier: Moderate
Handling Precautions: MK-677 capsules should be handled by trained laboratory personnel only. Use appropriate personal protective equipment (PPE) at all times, including gloves and eye protection. Avoid direct skin contact and inhalation during laboratory handling.
Exposure Risks: No human safety data has been established for the research-grade formulation supplied here. MK-677 did not complete clinical development, and no toxicological profile exists for this research-grade preparation.
Storage: Store at −20°C in a dry, dark environment protected from light, heat, and moisture. Check the batch Certificate of Analysis for lot-specific guidance. Do not use if the seal has been compromised.
Regulatory Status: MK-677 (Ibutamoren) is classified as a prohibited substance under the World Anti-Doping Agency (WADA) Prohibited List (category S2: Peptide Hormones, Growth Factors, Related Substances and Mimetics). This product is supplied strictly for controlled laboratory research and must not be used in any context involving athletic competition or human subjects.
Toxicity and Data Limitations: No chronic toxicity data exist for this research-grade preparation. MK-677 reached early-phase clinical investigation before development was discontinued; however, those findings do not apply to the research-grade formulation supplied here. Long-term exposure effects and systemic toxicity thresholds have not been characterized for this research preparation.
Why Choose BehemothLabz to Buy MK-677 Ibutamoren Capsules?
BehemothLabz offers MK-677 Ibutamoren Capsules for laboratory research purposes. Every batch goes through independent third-party testing for purity, identity, and contaminant screening. Testing is conducted using HPLC (High Performance Liquid Chromatography) and FTIR spectroscopy.
Each product batch carries a unique batch number linked to a publicly accessible Certificate of Analysis (COA). BehemothLabz does not self-certify. External labs verify every lot. This confirms purity at ≥99% and supports consistent research-grade standards per batch.
BehemothLabz Disclaimer
ATTENTION: All Behemoth Labz products are strictly for LABORATORY AND RESEARCH PURPOSES ONLY. They are not to be used for any human or veterinary purposes.
Please make sure you go through the Terms and Conditions and familiarize yourself with them, as it is important. Kindly research the scientific uses of this product before making any purchases. Make note that the packaging and labels of the product may differ from those shown on the website.
Buying the product means you agree to our Terms and Conditions. You can contact our customer service team at support@behemothlabz.com if you are not fully satisfied with the product.
MK-677 Ibutamoren Capsules Research FAQs
What purity standard does BehemothLabz provide for this product?
Every batch is independently tested by third-party laboratories. MK-677 Ibutamoren Capsules are verified at ≥99% purity by HPLC analysis. A Certificate of Analysis confirming purity and molecular identity is available per lot.
Is MK-677 a SARM?
No. MK-677 is not a SARM. SARMs are selective androgen receptor modulators. MK-677 acts on GHSR-1a (the ghrelin receptor). It is a growth hormone secretagogue, not an androgen receptor ligand.
Is MK-677 approved for human use?
No. MK-677 Ibutamoren is not approved by the U.S. Food and Drug Administration (FDA) for human or veterinary use. No regulatory body has cleared it for any health application. BehemothLabz sells it for laboratory research purposes only. Please review the Terms and Conditions before ordering.
What effects has MK-677 demonstrated on testosterone in preclinical models?
Available preclinical data show no consistent change in testosterone levels following MK-677 administration in animal models. Some studies document mild variation in GH/IGF-1 levels with extended administration periods. Findings are not consistent across experimental systems.
References
- Liu H, et al. Structural basis of human ghrelin receptor signaling by ghrelin and the synthetic agonist ibutamoren. Nature Communications. 2021;12(1):6430. https://doi.org/10.1038/s41467-021-26735-3
- Lee J, Kwon A, Kim YJ, Chae HW, Kim DH, Kim HS. Effect of the Orally Active Growth Hormone Secretagogue MK-677 on Somatic Growth in Rats. Yonsei Medical Journal. 2018;59(10):1174-1180. https://doi.org/10.3349/ymj.2018.59.10.1174
