MK-677

MK-677 is not a peptide. Chemically designated ibutamoren, and frequently referenced by its mesylate salt form, MK-677 is classified in pharmacological research literature as a non-peptide, orally bioavailable small molecule that functions as a ghrelin receptor agonist and growth hormone secretagogue. The distinction matters for researchers: growth hormone secretagogue is a functional category that includes both peptide compounds, such as GHRP-6, GHRP-2, hexarelin, ipamorelin, and sermorelin, and non-peptide small molecules like MK-677, and conflating the broader category with the peptide subclass is a common source of confusion in searches on this compound.

Structurally, MK-677 lacks the amino-acid backbone that defines a peptide. Its molecular formula, C27H36N4O5S, with a molar mass of approximately 528.7 g/mol, and its CAS registry number, 159634-47-6, are used across certificates of analysis to confirm compound identity ahead of any research protocol. Because it is a small organic molecule rather than a chain of amino acid residues, MK-677 is grouped separately from peptide-class ghrelin agonists in structural classification schemes, even though both classes are studied for overlapping receptor pharmacology.

In laboratory research, MK-677 is investigated as a ghrelin mimetic: it binds the growth hormone secretagogue receptor, GHS-R1a, with high affinity, engaging the same receptor pathway as endogenous ghrelin but without the rapid enzymatic deacylation that limits native ghrelin's utility as a research tool. Downstream, this receptor activation is studied for its role in pulsatile growth hormone release from the pituitary and subsequent hepatic IGF-1 production, positioning MK-677 as a reference compound in GH/IGF-1 axis research models. Its mechanism is described in the literature strictly in terms of receptor-binding pharmacology and signaling cascades observed in research systems.

Because MK-677 and peptide GH secretagogues converge on the same receptor target, researchers and search queries frequently group them together, which is the likely source of the recurring is MK-677 a peptide question. Peptide secretagogues under research investigation, including GHRP-6, GHRP-2, hexarelin, and ipamorelin, are short sequences of amino acids typically studied via reconstituted, injectable research protocols. MK-677 occupies a separate structural class as a non-peptide, orally studied small molecule, a distinction researchers rely on when documenting compound class or designing comparative GHS-R1a studies.

Beyond receptor pharmacology, MK-677 research spans several domains: GH/IGF-1 axis dynamics and pituitary secretory patterns, bone metabolism and turnover biomarkers, nitrogen balance and lean tissue parameters in preclinical models, and sleep architecture, particularly slow-wave and REM sleep stages recorded via polysomnography in research models. Ghrelin receptor pharmacology more broadly, including appetite-signaling pathways studied in animal models, is also a documented area of MK-677 investigation. All such findings are drawn from laboratory and preclinical literature and describe research-model observations rather than outcomes in human users.

MK-677 was originally developed under the research code MK-0677 in the mid-1990s as a non-peptide, orally active alternative to peptide GH secretagogues that otherwise required reconstitution and injection. Published research literature since that period has examined the compound's ghrelin receptor pharmacology and GH/IGF-1 axis effects, building a body of preclinical research literature that continues to inform current laboratory research design.

Optimum ReGen Peptides supplies MK-677 (ibutamoren) as a third-party tested research compound, with certificates of analysis confirming identity and purity by HPLC. Every batch is compounded through a licensed US pharmacy and distributed strictly for laboratory research use. MK-677 is not for human consumption, is not evaluated by the FDA for any medical use, and is not intended to diagnose, treat, cure, or prevent any disease; nothing on this page constitutes medical advice.

MK-677 (Ibutamoren) is in stock and available to buy online from Optimum ReGen Peptides — a real American research-peptide company with a physical storefront in Medford, Oregon, not an anonymous overseas dropshipper. Priced from $120, every order ships within two business days, flat $13 nationwide, in plain discreet packaging with tracking.

As your MK-677 supplier we back every batch with a third-party certificate of analysis and compound in a licensed US 503A pharmacy. Vials are supplied lyophilized at analytical purity for laboratory and research use only, not for human consumption.

In laboratory and controlled research settings, MK-677's effects on the GH/IGF-1 axis are typically assessed using serial blood sampling protocols combined with ultra-sensitive GH immunoassays and IGF-1 ELISA. Researchers use deconvolution analysis of GH pulsatility data to characterize changes in pulse amplitude, frequency, and interpulse trough levels following MK-677 administration.

Bone metabolism studies employ dual-energy X-ray absorptiometry (DXA) for bone mineral density measurement, alongside biochemical bone turnover markers (serum osteocalcin, bone alkaline phosphatase, urinary NTx) to characterize MK-677's effects on skeletal remodeling dynamics in research subjects over defined study periods.

Receptor biology experiments use radioligand binding assays with [125I]-labeled ghrelin or GHS peptides in GHSR-1a-expressing cell lines to measure MK-677 binding affinity and competitive displacement. Functional downstream assays measuring cAMP production, intracellular calcium flux, and ERK phosphorylation complete the pharmacological characterization of GHSR agonism in these systems.