Adrafinil vs Armodafinil

Mechanism

Inactive prodrug that is hepatically metabolized to modafinil (via hepatic amidase enzymes) and its inactive acid metabolite modafinilic acid. The active metabolite modafinil then exerts its effects as a DAT inhibitor with downstream orexinergic, histaminergic, and noradrenergic activation. Conversion is incomplete — approximately 33-50% of adrafinil is converted to modafinil, with the remainder forming inactive metabolites. The hepatic first-pass metabolism means onset is delayed (60-90 minutes vs. 30-60 minutes for modafinil).

Standard Dosing

300-600 mg once daily (for educational context — unregulated prodrug of a prescription medication)

Timing

Early morning on an empty stomach for faster hepatic conversion. Onset delayed 60-90 minutes. Avoid afternoon/evening dosing due to long effective duration.

Cycle Duration

Short-term or intermittent use strongly preferred. Avoid continuous daily use exceeding 3 months without liver function monitoring.

Side Effects

• All modafinil side effects apply
• Elevated liver enzymes (ALT/AST)
• Potential hepatotoxicity with chronic use
• Skin reactions
• GI distress (more common than with modafinil due to hepatic metabolism)

Contraindications

• Hepatic impairment of any severity
• Concurrent hepatotoxic medication
• All contraindications for modafinil apply (cardiac conditions, anxiety disorders, pregnancy)
• History of liver disease or elevated liver enzymes

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Mechanism

The isolated R-enantiomer of racemic modafinil, sharing the same primary mechanism — selective inhibition of the dopamine transporter (DAT) — but with distinct pharmacokinetics. The R-enantiomer has a terminal half-life of ~15 hours vs. ~4-5 hours for the S-enantiomer, resulting in 33-40% higher plasma AUC compared to equimolar racemic modafinil. This translates to more sustained wakefulness-promoting activity throughout the day. Same downstream activation of orexinergic, histaminergic, and noradrenergic pathways as modafinil.

Standard Dosing

75-150 mg once daily (for educational context only — prescription medication in most jurisdictions)

Timing

Early morning. 150 mg armodafinil provides comparable late-day wakefulness to 200 mg modafinil. Food delays Tmax by ~2-4 hours but does not affect total absorption. Half-life approximately 15-16.5 hours.

Cycle Duration

Same as modafinil; not typically cycled in clinical use.

Side Effects

• Headache
• Nausea
• Dizziness
• Insomnia (more pronounced than modafinil due to longer half-life)
• Anxiety
• Dry mouth
• Diarrhea
• Stevens-Johnson syndrome (very rare)

Contraindications

• Same as modafinil: mitral valve prolapse, left ventricular hypertrophy, severe hepatic impairment, severe anxiety/psychotic disorders, hypersensitivity, pregnancy

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