MK-677 (Ibutamoren)
Ghrelin Receptor Agonist | Oral Growth Hormone Secretagogue
Community Research
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Oral compound activating ghrelin receptors to trigger growth hormone release while preserving natural production. Achieves superior oral bioavailability exceeding 60% with a 24-hour half-life, making it unique among GH secretagogues for its convenient once-daily oral dosing.
Selectively binds GHS-R1a receptors in hypothalamus and pituitary, triggering pulsatile growth hormone release while maintaining natural circadian patterns.
Molecular Data
Research Indications
Restores youthful growth hormone levels in elderly subjects with 97% increase in 24-hour secretion.
Sustained 40-72% IGF-1 elevation over extended periods.
20% REM increase in younger adults; 50% improvement in elderly.
Demonstrates +2.69g/day nitrogen retention versus -8.97g/day placebo, protecting lean mass during caloric restriction.
Increases fat-free mass with preferential lean tissue accrual.
15% basal metabolic rate elevation documented at 2 weeks.
39-45% increase in bone formation markers within 6-8 weeks.
Dosing Protocols
Optimal bioavailability eliminates injection requirements with convenient daily dosing. Take at bedtime on empty stomach for best results.
Body composition/anti-aging
25mg
1x daily
Oral (bedtime, empty stomach)
Sleep quality improvement
1x nightly
Oral (30 minutes before bed)
Conservative initiation
12.5mg
Oral (assess tolerance)
Interactions
What to Expect
Side Effects & Safety
Common Side Effects
Appetite stimulation (>50% of users)
Water retention (30-40%)
Lethargy (20-30%)
Fasting glucose elevation (5-15mg/dL)
Note on testosterone suppression: at doses up to 20 mg daily, MK-677 is unlikely to cause significant testosterone suppression on its own. Above 20 mg daily, the likelihood of suppression and other side effects (insulin resistance, water retention, lethargy) increases. The case report documenting 85.7% testosterone suppression involved co-administration with LGD-4033, a SARM known to be profoundly suppressive, making the SARM the likely primary driver of that suppression.
Stop Signs - Discontinue if:
Shortness of breath, chest pain, or unusual fatigue
Blood glucose levels >100mg/dL or diabetes symptoms
Liver enzyme elevation (ALT/AST >2x upper normal)
Severe fluid retention or unexplained swelling
Any concerning cardiovascular symptoms
Contraindications
Heart disease or congestive heart failure
Diabetes or pre-diabetes
Active cancer
Severe cardiovascular disease
Pregnancy or breastfeeding
Quality Checklist
Good Signs
Pharmaceutical-grade capsules with professional labeling
Batch numbers and expiration dates
Third-party testing documentation
Certificate of analysis showing >98% purity
Warning Signs
Products labeled 'for research only' may lack quality control
Bad Signs
Dietary supplement claims (FDA prohibits MK-677 in supplements)
Unknown purity or source without certificates of analysis
Unusually low prices suggesting counterfeit product
Frequently Asked Questions
Why is MK-677 oral when most peptides are injected?
MK-677 is not actually a peptide—it's a small-molecule non-peptide ghrelin receptor agonist with excellent oral bioavailability (>60%) and a 24-hour half-life. This allows convenient once-daily oral dosing without injections, making it uniquely practical among GH secretagogues.
Does MK-677 increase testosterone suppression when combined with SARMs?
At doses up to 20mg daily, MK-677 alone causes minimal testosterone suppression. However, one case report documented 85.7% testosterone suppression when combined with LGD-4033 (a SARM). The SARM was likely the primary driver of suppression, not MK-677.
How much does MK-677 increase appetite?
Appetite stimulation affects >50% of users at 25mg doses. This is direct ghrelin mimicry—the same mechanism that increases GH. If appetite stimulation is problematic, reduce dose to 12.5mg or use ipamorelin instead for cleaner GH elevation without hunger.
Does MK-677 cause water retention?
Yes. 30-40% of users experience water retention from MK-677's GH stimulation and sodium retention effects. This appears within the first 2-4 weeks. Sodium management and adequate hydration help minimize bloating, and effects often diminish over time as the body adapts.
References
Randomized, double-blind crossover in 9 healthy young men. 7-day oral MK-677 (5 and 25mg) increased 24-hour GH profiles dose-dependently while preserving circadian patterns.
Randomized, double-blind trial in 32 elderly subjects (64-81 years). 25mg/day MK-677 for up to 4 weeks increased mean 24-hour GH by 97% and restored IGF-I concentrations to young adult levels.
In young adults, 25mg MK-677 increased stage IV sleep duration by 50% and REM sleep by 20%. In older adults, REM sleep increased nearly 50% with decreased REM latency. Sleep deviations dropped from 42% to 8%.
Double-blind crossover in 8 healthy volunteers under caloric restriction. 25mg/day MK-677 for 7 days reversed nitrogen wasting (+2.69g/day vs -8.97g/day placebo) and significantly increased IGF-I.
24 obese males treated with 25mg/day for 8 weeks showed sustained increases in GH, IGF-I, fat-free mass, and a transient increase in basal metabolic rate at 2 weeks.
187 elderly adults (65+) across three placebo-controlled studies. 9 weeks of MK-677 increased serum osteocalcin by 29.4%, bone-specific alkaline phosphatase by 10.4%, and urinary NTX by 22.6%.
12-month RCT in 65 healthy adults (60-81 years). MK-677 increased GH and IGF-I to young adult levels, increased fat-free mass while placebo group declined, and was generally well tolerated.
Related Peptides
Both stimulate GH release through different mechanisms.
MK-677 baseline elevation combines with GHRP-2 pulsatile spikes.
Non-competing mechanisms enhancing recovery effects.
Systemic growth factors complement localized healing.
Disclaimer
This information is for educational and research purposes only. Consult a healthcare professional before use.