Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| Armodafinil | Phenibut | |
|---|---|---|
| Category | Nootropics | Nootropics |
| Standard Dose | 75-150 mg once daily (for educational context only — prescription medication in most jurisdictions) | 250-750 mg as needed, maximum 1-2 times per week (for educational context — carries significant dependence risk) |
| 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. | On an empty stomach (food significantly reduces absorption). Onset 2-4 hours. Effects last 4-8 hours with residual effects up to 24 hours. Half-life approximately 5.3 hours. |
| Cycle Duration | Same as modafinil; not typically cycled in clinical use. | STRICTLY intermittent use only — maximum 1-2 times per week. NEVER use daily for more than 1 week. Tolerance develops within days, leading to dose escalation and dependence. |
| Evidence Level | strong_human | moderate_human |
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.
75-150 mg once daily (for educational context only — prescription medication in most jurisdictions)
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.
Same as modafinil; not typically cycled in clinical use.
Beta-phenyl derivative of GABA that crosses the blood-brain barrier (unlike GABA itself) due to the addition of a phenyl ring. Acts as a full agonist at GABA-B receptors with 30-68x lower affinity than baclofen, requiring correspondingly higher doses. Also binds to and blocks alpha-2-delta subunit-containing voltage-dependent calcium channels (VDCCs), making it a gabapentinoid similar to gabapentin and pregabalin. At low concentrations, mildly increases dopamine levels in the brain, providing stimulatory and nootropic effects alongside anxiolysis. Weak agonist activity at GABA-A receptors at higher doses.
250-750 mg as needed, maximum 1-2 times per week (for educational context — carries significant dependence risk)
On an empty stomach (food significantly reduces absorption). Onset 2-4 hours. Effects last 4-8 hours with residual effects up to 24 hours. Half-life approximately 5.3 hours.
STRICTLY intermittent use only — maximum 1-2 times per week. NEVER use daily for more than 1 week. Tolerance develops within days, leading to dose escalation and dependence.
Take our free assessment to get personalized recommendations based on your health goals, current stack, and biomarkers.
Get Your Free Protocol →or take the assessment →