# MK-677 (Capsule)

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- Published: 2026-08-29
- Author: Best Health IQ
- Summary: The only oral GH secretagogue — stimulates GH and IGF-1 through ghrelin receptor activation.
- Shopper link: https://www.besthealthiq.com/__fluid_affiliate_username__/posts/mk-677-capsule

\*\*MK-677 (Ibutamoren)\*\* · Hormone & GH · Moderate Evidence · Research Only The only oral GH secretagogue — stimulates GH and IGF-1 through ghrelin receptor activation. ### Competition Status Prohibited in competition. This compound is on the WADA Prohibited List (class \[S0 / S2.3 / S2\]), banned at all times, both in and out of competition. Athletes subject to WADA or USADA testing should not use it. ### Description MK-677 (Ibutamoren, also known as L-163,191) is a non-peptide oral growth hormone secretagogue that mimics the action of ghrelin and activates the GHS-R1a (growth hormone secretagogue receptor 1a). It is the only orally bioavailable GH secretagogue, providing a convenient alternative to injectable GHRPs (growth hormone releasing peptides) such as GHRP-2 and GHRP-6. MK-677 was developed by Merck and has been evaluated in multiple Phase II human clinical trials for conditions including GH deficiency, muscle wasting, hip fracture recovery, and Alzheimer’s disease. It significantly elevates both pulsatile GH secretion and IGF-1 levels, with effects lasting approximately 24 hours from a single dose. Unlike injectable GH, MK-677 stimulates the body’s own GH production in a physiological pulsatile pattern, which is considered safer and more natural than exogenous GH administration. The compound has demonstrated improvements in body composition, bone mineral density, and sleep quality in human studies. ### Key Characteristics - \*\*Molecular Weight:\*\* Not specified - \*\*Half-Life:\*\* Varies - \*\*Administration Routes:\*\* Oral capsule - \*\*Typical Dose:\*\* One capsule (per prescriber guidance) - \*\*Frequency:\*\* Once daily (bedtime) - \*\*Cycle Length:\*\* 8–16 weeks ### Investigated Benefits - Increased GH and IGF-1 - Enhanced sleep quality - Convenient oral administration - Improved body composition - Increased bone density - Improved skin quality \\\* Benefits based on preclinical/animal research unless otherwise noted. ### Mechanism of Action MK-677 binds to and activates the ghrelin receptor (GHS-R1a) in the pituitary gland and hypothalamus, mimicking the action of the endogenous hunger hormone ghrelin. This activation stimulates the pituitary to release GH in pulsatile bursts, which in turn stimulates the liver to produce IGF-1 (insulin-like growth factor 1). Unlike synthetic GH, MK-677 preserves the natural pulsatile pattern of GH secretion, which is important for maintaining GH receptor sensitivity and avoiding the desensitization that can occur with continuous GH exposure. MK-677 has a half-life of approximately 24 hours, allowing for once-daily dosing. Bedtime administration aligns with the natural nocturnal GH pulse and may enhance sleep quality through GH’s effects on slow-wave sleep architecture. The compound also increases ghrelin signaling in the hypothalamus, which stimulates appetite — a common and expected effect that should be managed through dietary awareness. ### Dosing & Protocol - \*\*Typical Dose:\*\* One capsule (per prescriber guidance) - \*\*Frequency:\*\* Once daily (bedtime) - \*\*Cycle Length:\*\* 8–16 weeks - \*\*Administration:\*\* Oral capsule \*\*Protocol Notes:\*\* Bedtime dosing aligns with natural GH pulse. Start with 10 mg to assess tolerance. Increased hunger is common — manage caloric intake. Monitor IGF-1 every 3 months. ### Storage Information Store at room temperature, away from light and moisture. ### Quality & Sourcing Standards When sourcing MK-677 (Capsule) for research purposes, the following quality benchmarks should be verified before use. - \*\*Purity:\*\* \>98% (verified by HPLC) - \*\*Certificate of Analysis (COA):\*\* Must be provided by supplier - \*\*Endotoxin Testing:\*\* \<0.1 EU/mg (prevents bacterial contamination) - \*\*GMP Compliance:\*\* Manufactured in cGMP-certified facility - \*\*Third-Party Testing:\*\* Independent lab verification preferred ### Research Highlights 1. Demonstrated significant GH and IGF-1 elevation in human Phase II trials 2. Improved body composition in elderly patients 3. Increased bone mineral density in Phase II trials ### Evidence Level \*\*Moderate Evidence\*\* — Multiple animal studies and/or early human trials. Reasonable confidence in mechanism, but human data is limited. ### FDA Disclaimer The statements made within this website have not been evaluated by the US Food and Drug Administration. The products and information provided are not intended to diagnose, treat, cure, or prevent any disease. This website is intended for educational and research purposes only. Many peptides described on this site are not approved by the FDA for human therapeutic use and are classified as research chemicals. Nothing on this site constitutes medical advice.