MK-677 vs Naltrexone
Well Studied vs FDA Approved
avoid Mechanism-based · 64% Both MK-677 and Naltrexone carry hepatotoxic risk. Combining hepatotoxic compounds significantly increases liver damage potential. If unavoidable, include liver support (TUDCA/NAC) and monitor ALT/AST frequently.
Molecular Data
MK-677 Naltrexone
Weight 624.77 Da 341.40 Da
Half-life ~24 hours ~4 hours
Type Non-peptide ghrelin receptor agonist Opioid antagonist (C20H23NO4)
Key Benefits
MK-677
01 97% increase in 24-hour growth hormone secretion
02 40-72% elevation in IGF-1 levels
03 Enhanced sleep quality with improved REM patterns
04 Preferential lean tissue gains of 1.1-2.7kg over 8-12 months
05 15% basal metabolic rate increase within 2 weeks
06 Oral administration (no injections required)
Naltrexone
01 Broad anti-inflammatory and immunomodulatory effects via OGF-OGFr axis upregulation
02 Reduction in pro-inflammatory cytokines (TNF-alpha, IL-6, IL-12) through TLR4 antagonism
03 Compensatory upregulation of endogenous endorphins and enkephalins (200-300% increase)
04 Improved immune regulation and rebalancing of Th1/Th2/Th17 responses
05 Reduction in chronic pain through central and peripheral opioid system modulation
06 Potential improvement in mood, anhedonia, and overall well-being via endorphin enhancement
07 Extremely well-tolerated with minimal side effects at low doses
08 Low cost, especially as compounded LDN formulation
Side Effects
MK-677
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.
Naltrexone
Vivid dreams or unusually intense dreaming - the most frequently reported side effect, typically diminishes over 1-2 weeks
Initial sleep disruption or insomnia during the first week of treatment
Mild nausea, particularly during the first few days
Transient headache during dose initiation or titration
Contraindications
Heart disease or congestive heart failure
Diabetes or pre-diabetes
Active cancer
Severe cardiovascular disease
Pregnancy or breastfeeding
Current use of opioid medications or active opioid dependence (must be opioid-free 7-10 days minimum)
Acute hepatitis or severe hepatic impairment (primarily relevant at full dose)
Known hypersensitivity to naltrexone
Anticipated need for opioid pain medication (e.g., upcoming surgery - discontinue LDN 3-7 days prior)
Research Evidence
MK-677 Naltrexone
Status Well Studied FDA Approved
References 7 studies 5 studies
Latest July 2024 2023
FDA Approved No Yes
This comparison is for educational and research purposes only. Consult a healthcare professional before use.