Aniracetam vs Fasoracetam

Mechanism

Potent positive allosteric modulator of AMPA receptors with 5-10x the potency of piracetam, slowing both channel closing rate and microscopic desensitization rates. Also modulates metabotropic glutamate receptors (mGluRs), activates nicotinic acetylcholine receptors, and indirectly boosts dopaminergic and serotonergic neurotransmission, conferring anxiolytic properties.

Standard Dosing

750-1500 mg/day divided into 2-3 doses

Timing

With fat-containing meals (fat-soluble compound; bioavailability increases significantly with dietary fat)

Cycle Duration

Cycles of 8-12 weeks on, 4 weeks off

Side Effects

• Headache (choline depletion)
• GI discomfort
• Restlessness
• Insomnia if taken late

Contraindications

• Severe hepatic impairment (hepatically metabolized)
• Known hypersensitivity to racetams

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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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