Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| Fasoracetam | Modafinil | |
|---|---|---|
| Category | Nootropics | Nootropics |
| Standard Dose | 20-100 mg 1-3 times daily (sublingual or oral) | 100-200 mg once daily (for educational context only — prescription medication in most jurisdictions) |
| Timing | Morning and afternoon. Sublingual administration may provide faster onset and higher bioavailability. With or without food. | Early morning to avoid insomnia; 1 hour before desired peak alertness. With or without food (food slows absorption by ~1 hour but does not reduce bioavailability). Half-life is approximately 12-15 hours. |
| Cycle Duration | Cycles of 4-8 weeks on, 2-4 weeks off. Limited long-term safety data. | Not typically cycled in clinical use. Some off-label users cycle to maintain sensitivity (5 days on, 2 off; or as-needed use). |
| Evidence Level | animal_plus_anecdotal | strong_human |
Non-classical racetam that modulates all three groups of metabotropic glutamate receptors (mGluR Groups I, II, and III) and upregulates GABA-B receptors — a unique mechanism that distinguishes it from other racetams. Also enhances high-affinity choline uptake (HACU) and stimulates acetylcholine release. Does not significantly affect adrenergic, serotonergic, or dopaminergic receptors. The GABA-B upregulation is particularly notable as it may counteract GABA-B receptor downregulation caused by phenibut or baclofen tolerance.
20-100 mg 1-3 times daily (sublingual or oral)
Morning and afternoon. Sublingual administration may provide faster onset and higher bioavailability. With or without food.
Cycles of 4-8 weeks on, 2-4 weeks off. Limited long-term safety data.
Atypical eugeroic (wakefulness-promoting agent) that primarily inhibits the dopamine transporter (DAT), increasing extracellular dopamine in the prefrontal cortex and nucleus accumbens. This primary action cascades through multiple systems: indirect activation of orexinergic neurons in the lateral hypothalamus via potentiation of glutamatergic transmission; downstream stimulation of histaminergic neurons in the tuberomammillary nucleus (via orexin-mediated disinhibition of GABAergic inputs); and enhancement of norepinephrine release in the locus coeruleus. The net effect is broad-spectrum arousal without the peripheral sympathomimetic effects of classical stimulants.
100-200 mg once daily (for educational context only — prescription medication in most jurisdictions)
Early morning to avoid insomnia; 1 hour before desired peak alertness. With or without food (food slows absorption by ~1 hour but does not reduce bioavailability). Half-life is approximately 12-15 hours.
Not typically cycled in clinical use. Some off-label users cycle to maintain sensitivity (5 days on, 2 off; or as-needed use).
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