Fasoracetam vs Piracetam

Mechanism

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.

Standard Dosing

20-100 mg 1-3 times daily (sublingual or oral)

Timing

Morning and afternoon. Sublingual administration may provide faster onset and higher bioavailability. With or without food.

Cycle Duration

Cycles of 4-8 weeks on, 2-4 weeks off. Limited long-term safety data.

Side Effects

• Headache
• Fatigue
• GI discomfort
• Irritability
• Brain fog (paradoxical, at excessive doses)

Contraindications

• Known hypersensitivity to racetams
• Pregnancy and lactation (no safety data)
• Severe renal or hepatic impairment

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Mechanism

Positive allosteric modulator of AMPA receptors, binding at a unique site along the dimer interface to reduce desensitization and deactivation. Inhibits N-type calcium channels at clinically relevant CNS concentrations. Enhances membrane fluidity of neuronal phospholipids and modulates neurotransmission across cholinergic and glutamatergic systems.

Standard Dosing

1200-4800 mg/day divided into 2-3 doses

Timing

With or without food; split doses morning and afternoon to maintain plasma levels

Cycle Duration

Cycles of 8-12 weeks on, 4 weeks off; or ongoing with periodic reassessment

Side Effects

• Headache (often from inadequate choline)
• Insomnia
• GI discomfort
• Irritability at high doses

Contraindications

• Severe renal impairment (renally excreted)
• Huntington's disease
• Cerebral hemorrhage

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