MK-677 vs Modafinil
Well Studied vs FDA Approved
avoid Mechanism-based · 64% Both MK-677 and Modafinil 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 Modafinil
Weight 624.77 Da 273.35 Da
Half-life ~24 hours ~12-15 hours
Type Non-peptide ghrelin receptor agonist Diphenylmethylsulfinylacetamide (C15H15NO2S)
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)
Modafinil
01 Sustained wakefulness and alertness for 10-15 hours without the jitteriness of traditional stimulants
02 Enhanced executive function, working memory, and decision-making under fatigue
03 Improved focus and concentration during prolonged cognitive tasks
04 Reduced impulsivity and improved task completion in sleep-deprived individuals
05 Low abuse potential relative to amphetamine-class stimulants (Schedule IV)
06 Minimal impact on normal sleep architecture when taken in the morning
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.
Modafinil
Headache (most frequently reported side effect, often dose-dependent)
Insomnia (particularly if taken too late in the day)
Anxiety and nervousness
Appetite suppression and mild nausea
Dry mouth
Dizziness
Gastrointestinal discomfort (diarrhea, abdominal pain)
Contraindications
Heart disease or congestive heart failure
Diabetes or pre-diabetes
Active cancer
Severe cardiovascular disease
Pregnancy or breastfeeding
Known hypersensitivity to modafinil or armodafinil
History of Stevens-Johnson Syndrome, TEN, or DRESS with prior modafinil/armodafinil use
Severe hepatic impairment (dose reduction required in moderate impairment)
Unstable angina or recent myocardial infarction
Left ventricular hypertrophy or clinically significant mitral valve prolapse with prior stimulant use
Pregnancy (limited human data; animal studies show teratogenicity at high doses)
Research Evidence
MK-677 Modafinil
Status Well Studied FDA Approved
References 7 studies 5 studies
Latest July 2024 —
FDA Approved No Yes
This comparison is for educational and research purposes only. Consult a healthcare professional before use.