MK-677 Capsules (25mg) 60 Count

Oral GH Secretagogue: Non-peptide ghrelin mimetic (C₂₇H₃₆N₄O₅S), >60% bioavailability
GHS-R1a Agonist: High affinity (pKi = 8.14, EC50 = 1.3 nM), sustained GH-IGF-1 elevation
Clinical Evidence: 30-year history, >1,000 subjects, Phase 3 development for pediatric GHD

Manufacturer: RiboCore

Availability: In stock

SKU: RC-MK-677-CAPSULES-25MG

$99.00

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Technical Specifications

Characteristic	Value
CAS Number	159634-47-6
Molecular Weight	528.66 Da
Molecular Formula	C₂₇H₃₆N₄O₅S
Class	Non-peptide growth hormone secretagogue
Purity	≥98% (HPLC)
Form	Capsules (25mg)

MK-677 (ibutamoren, MK-0677, L-163,191, LUM-201) is a potent, orally active, non-peptide growth hormone secretagogue that selectively agonizes the GHS-R1a (ghrelin receptor). First developed by Merck & Co. in the mid-1990s, MK-677 has been extensively studied in over 1,000 subjects across randomized controlled trials spanning nearly three decades. Unlike peptide-based GH secretagogues requiring injection, MK-677 demonstrates oral bioavailability exceeding 60% and a prolonged half-life enabling once-daily dosing.

MK-677 features a unique spirocyclic architecture linking an indoline ring system to a piperidine moiety. Cryo-EM structural analysis at 2.7 Å resolution revealed that ibutamoren binding induces conformational changes through an E124-R283 salt bridge mechanism and W276 toggle switch, enabling G protein coupling and downstream GH release.

Key Research Highlights

Research Area	Key Finding
Elderly GH Restoration	25 mg daily increased GH by 97% and restored IGF-1 from 141 to 265 μg/L in adults ages 64-81 (Chapman et al., 1996)
Body Composition	2-year trial: fat-free mass +1.1 kg vs. -0.5 kg placebo (P < 0.001); LDL -5.4 mg/dL; sustained without tachyphylaxis (Nass et al., 2008)
Nitrogen Balance	Reversed diet-induced catabolism: +0.31 g/day vs. -1.48 g/day placebo (P < 0.01) in calorie-restricted subjects (Murphy et al., 1998)
Sleep Quality	~50% increase in stage IV sleep and >20% increase in REM sleep; deviations from normal sleep decreased from 42% to 8% (Copinschi et al., 1997)
Pediatric GHD	Phase 2 (LUM-201): 8.0 cm/year height velocity; 62% GH increase, 80% IGF-1 increase at 6 months; Phase 3 planned
Neuroprotection	Reduced amyloid beta to 30% of controls, decreased neuroinflammation in 5XFAD mice (Jeong et al., 2018)

Research Applications

Growth hormone-IGF-1 axis research and somatopause
Pediatric growth hormone deficiency (Phase 3 development)
Body composition and lean mass preservation in elderly
Bone metabolism and osteoporosis research
Sleep physiology and architecture modulation
Catabolic disease states and nitrogen balance
Neuroprotection and Alzheimer's disease models
Ghrelin receptor pharmacology and structural biology