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.
| Goal | Dose | Frequency | Route |
|---|---|---|---|
| Body composition/anti-aging | 25mg | 1x daily | Oral (bedtime, empty stomach) |
| Sleep quality improvement | 25mg | 1x nightly | Oral (30 minutes before bed) |
| Conservative initiation | 12.5mg | 1x daily | 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
References
- Effects of a 7-day treatment with a novel, orally active, growth hormone (GH) secretagogue, MK-677, on 24-hour GH profiles, insulin-like growth factor I, and adrenocortical function in normal young menCopinschi, G., et al.Journal of Clinical Endocrinology & Metabolism (1996)
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.
- Stimulation of the growth hormone (GH)-insulin-like growth factor I axis by daily oral administration of a GH secretagogue (MK-677) in healthy elderly subjectsChapman, I.M., et al.Journal of Clinical Endocrinology & Metabolism (1996)
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.
- Prolonged oral treatment with MK-677, a novel growth hormone secretagogue, improves sleep quality in manCopinschi, G., et al.Neuroendocrinology (1997)
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%.
- MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolismMurphy, M.G., et al.Journal of Clinical Endocrinology & Metabolism (1998)
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.
- Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditureChapman, I.M., et al.Journal of Clinical Endocrinology & Metabolism (1998)
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.
- Oral administration of the growth hormone secretagogue MK-677 increases markers of bone turnover in healthy and functionally impaired elderly adultsMurphy, M.G., et al.Journal of Bone and Mineral Research (1999)
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%.
- Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trialNass, R., et al.Annals of Internal Medicine (2008)
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.
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Disclaimer
This information is for educational and research purposes only. Consult a healthcare professional before use.