MK-2866 vs Modafinil
Moderate Research vs FDA Approved
avoid Mechanism-based · 64% Both MK-2866 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-2866 Modafinil
Weight 389.33 Da 273.35 Da
Half-life ~24 hours ~12-15 hours
Type Non-steroidal selective androgen receptor modulator (C19H14F3N3O3) Diphenylmethylsulfinylacetamide (C15H15NO2S)
Key Benefits
MK-2866
01 Increases lean body mass in a dose-dependent manner with clinical trial support
02 Preserves muscle mass during caloric deficit or catabolic conditions
03 Selective tissue activity reduces androgenic side effects compared to anabolic steroids
04 Oral bioavailability eliminates the need for injections
05 Does not aromatize to estrogen, avoiding gynecomastia and water retention
06 Improves physical function and stair-climbing power in clinical populations
07 Long 24-hour half-life allows convenient once-daily dosing
08 Mild side effect profile at commonly studied doses
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-2866
Mild testosterone suppression (dose-dependent, typically 10-30% reduction at 25 mg)
HDL cholesterol reduction (10-20% suppression observed in clinical trials)
Headaches, particularly during the first 1-2 weeks
Mild back pain or muscle cramps
Transient fatigue toward the end of longer cycles
Slight reduction in libido at higher doses or extended cycle lengths
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
Active liver disease or significantly elevated liver enzymes
Hormone-sensitive cancers (breast, prostate) without oncologist clearance
Pregnancy or breastfeeding (potential endocrine disruption to fetus/infant)
Individuals under 21 years of age (risk of premature HPTA disruption during development)
Concurrent use of hepatotoxic medications without liver function monitoring
Known hypersensitivity to MK-2866 or any formulation excipients
Competitive athletes subject to WADA or USADA anti-doping testing
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-2866 Modafinil
Status Moderate Research FDA Approved
References 5 studies 5 studies
FDA Approved No Yes
This comparison is for educational and research purposes only. Consult a healthcare professional before use.