Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| Fasoracetam | Phenylpiracetam | |
|---|---|---|
| Category | Nootropics | Nootropics |
| Standard Dose | 20-100 mg 1-3 times daily (sublingual or oral) | 100-300 mg/day divided into 1-2 doses |
| Timing | Morning and afternoon. Sublingual administration may provide faster onset and higher bioavailability. With or without food. | Morning or early afternoon; avoid evening use due to stimulant effects. Take with or without food. |
| Cycle Duration | Cycles of 4-8 weeks on, 2-4 weeks off. Limited long-term safety data. | Use sparingly — tolerance develops rapidly. Best cycled 2 weeks on, 2 weeks off, or reserved for acute-need situations. |
| Evidence Level | animal_plus_anecdotal | moderate_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 dopamine reuptake inhibitor with additional phenethylamine-like stimulatory properties. Increases the density of acetylcholine, NMDA, GABA, and dopamine receptors in the brain. The phenyl group addition to the piracetam backbone enables blood-brain barrier penetration at 20-60x greater potency than piracetam, with added psychostimulant and cold-tolerance properties.
100-300 mg/day divided into 1-2 doses
Morning or early afternoon; avoid evening use due to stimulant effects. Take with or without food.
Use sparingly — tolerance develops rapidly. Best cycled 2 weeks on, 2 weeks off, or reserved for acute-need situations.
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