Sleep & GH

MK-677

Ibutamoren, MK-0677, L-163,191, Nutrobal

MK-677 (Ibutamoren) is the only orally active growth hormone secretagogue — a non-peptide ghrelin mimetic that produces sustained 24-hour GH and IGF-1 elevation with a single daily dose, without injections.

Oral Intermediate
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This peptide profile is for research and educational purposes only. Not intended for human use or self-administration.

Overview

MK-677 (Ibutamoren) is a non-peptide small molecule that acts as a potent ghrelin receptor agonist (GHSR-1a), producing significant and sustained growth hormone release with oral administration. Developed by Merck in the 1990s, it has been studied in clinical trials for GH deficiency, muscle wasting, obesity, and frailty in the elderly. Unlike injectable GH secretagogue peptides that produce short, acute GH pulses, MK-677 produces an elevated GH and IGF-1 baseline that persists throughout the day — a different pharmacological profile that makes it suitable for different research objectives and population groups who cannot or prefer not to inject.

Mechanism of Action

MK-677 binds to and activates GHSR-1a (the ghrelin receptor) in the hypothalamus and pituitary, triggering GH release and simultaneously inhibiting somatostatin. Because it is orally bioavailable and has a ~24-hour half-life, a single daily dose produces continuously elevated GH and IGF-1 levels — unlike injectable GHRPs, which produce discrete acute pulses. The persistent GH elevation drives hepatic IGF-1 production, which mediates anabolic, lipolytic, and reparative downstream effects including increased lean mass, reduced fat mass, improved sleep architecture, enhanced skin and hair quality, and accelerated tissue repair. IGF-1 elevation also has important implications for monitoring and dose management.

Key Research

MK-677 has been studied in numerous human clinical trials. A 12-month trial in elderly adults (N=65, >60 years) showed significant increases in IGF-1, lean body mass, and gait speed. A 2-year study in GH-deficient adults showed improved body composition and bone mineral density. Studies in healthy young men demonstrated dose-dependent GH and IGF-1 elevation. Sleep architecture studies confirmed MK-677 increases REM and slow-wave sleep duration — a distinctive benefit. Multiple trials in patients with hip fractures showed improved bone density and functional recovery. It has not received FDA approval for any indication, though clinical evidence suggests safety at standard doses in non-diabetic adults.

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Research Dosing

Typical Dose

12.5–25 mg orally once daily

Half-Life

~24 hours

Standard research dose is 12.5–25 mg once daily, taken orally with or without food. Evening or pre-bed dosing is preferred to synchronize with the natural nocturnal GH peak and take advantage of MK-677's sleep quality improvements. Dosing with food reduces GI discomfort. Start at 12.5 mg and assess tolerance (especially hunger and water retention) before increasing to 25 mg. Cycles of 16–24 weeks are common; some protocols use 8-week cycles with breaks. IGF-1 levels should be checked at baseline and 4–6 weeks into the cycle — dose reduction indicated if IGF-1 exceeds normal range.
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Protocols

Sleep and Recovery Protocol: MK-677 12.5–25 mg orally before bed for 16–20 weeks. Combine with BPC-157 250 mcg SC daily for tissue repair synergy (MK-677 drives GH-axis anabolism; BPC-157 accelerates local healing). Body Composition Stack: MK-677 25 mg nightly + AOD-9604 300 mcg SC fasted mornings for GH elevation (MK-677) and targeted fat mobilization (AOD-9604). Anti-Aging Protocol: MK-677 12.5 mg nightly for 6 months combined with Epithalon pulse cycles.

Reported Side Effects

Side effects summarized from animal studies and researcher community observations. Educational purposes only — not medical advice.
MK-677's most commonly reported side effects are increased appetite (significant in some users — hunger surges are common in the first 2–4 weeks), water retention (mild to moderate, particularly in the hands and face), and transient increases in fasting blood glucose and insulin resistance. These metabolic effects are important monitoring points — MK-677 is not appropriate for individuals with pre-diabetes or diabetes without medical supervision. Joint pain and mild fatigue from the sustained GH elevation are reported, particularly at 25 mg. Unlike injectable GHRPs, the sustained IGF-1 elevation raises theoretical long-term proliferative concerns — IGF-1 monitoring is essential for extended cycles. Headache and dizziness occur in some users early in a cycle.

Storage & Handling

Oral tablets or capsules — store at room temperature (15–25°C) in a sealed container away from moisture and light. Standard shelf life of 2+ years when stored properly. Keep away from heat. No special cold storage required — a practical advantage over injectable peptides.