Glutamatergic

Aniracetam is a fat-soluble piracetam analog that positively modulates AMPA glutamate receptors. It was marketed in Italy and Japan for dementia and post-stroke cognitive symptoms, and placebo-controlled trials in Alzheimer-type dementia gave contradictory answers. It is no longer in clinical use, and in healthy animals it does nothing measurable.

Fasoracetam is a racetam repurposed as a metabotropic glutamate receptor activator and trialed in adolescents with ADHD who carry disruptive variants in mGluR network genes. A 30-patient open-label dose-escalation study with one single-blind placebo week reported significant improvement on global rating scales and good tolerability. That is a phase I result and the only human efficacy evidence there is.

L-theanine is an amino acid found almost only in tea. Taken at 200 to 400 mg a day, it may reduce stress and anxiety in people under stressful conditions. Its best-known use is alongside caffeine, where the pair improves attention switching more than either alone. A 2025 meta-analysis found small improvements in subjective sleep.

Memantine is a prescription adamantane derivative that blocks pathologically active NMDA receptor channels with moderate affinity and fast on-off kinetics. A Cochrane review of 44 trials found small but consistent benefits in cognition, daily function, global status and behavior in moderate-to-severe Alzheimer's disease, with or without a cholinesterase inhibitor; it found no benefit in mild Alzheimer's disease. It slows deterioration rather than restoring lost cognition.

N-acetylcysteine (NAC) is an acetylated form of the amino acid cysteine. It is the standard antidote for acetaminophen (acetaminophen) overdose, a mucolytic that modestly cuts flare-ups of COPD and chronic bronchitis, and a widely sold supplement. Its psychiatric uses rest on a mixed record: a positive trial in adolescents who used cannabis failed to repeat in adults, and large trials found no benefit for idiopathic pulmonary fibrosis or for protecting the kidneys during angiography. Only about a tenth of an oral dose reaches the blood.

Nefiracetam is a Japanese piracetam derivative that potentiates nicotinic α4β2 and NMDA receptors at nanomolar concentrations, through Gs proteins and protein kinase C. Its human testing went in an unexpected direction — post-stroke depression and apathy rather than memory — and the results were mixed at best: no overall antidepressant effect in 159 patients, a positive apathy signal in one trial and nothing in a second that could only randomize 13.

Noopept is a Russian dipeptide designed to mimic the piracetam pharmacophore, reported active at doses about a thousandth of piracetam's. It is a prodrug: the parent is undetectable in rat brain an hour after dosing, and the active species is cycloprolylglycine, a peptide the brain already makes. Its clinical evidence is Russian, small and uncontrolled, and its primary molecular action appears to be stabilization of HIF-1.

Piracetam is the original "nootropic". C. Giurgea developed it in the late 1960s and coined the word to describe it. It is licensed in several countries for cognitive disorders, vertigo and cortical myoclonus. The evidence is mixed. An older meta-analysis found a global benefit in older adults with cognitive impairment, but a 2024 meta-analysis could not confirm an effect on memory.

TAK-653 (osavampator, NBI-1065845) is an AMPA receptor positive allosteric modulator designed to amplify glutamate signaling only where glutamate is already being released — it binds the receptor's ligand-binding domain in a glutamate-dependent way and has virtually no agonist activity of its own, which in rats bought a 419-fold exposure margin against convulsions. In 24 healthy volunteers a single 6 mg dose raised motor-cortex excitability on TMS and produced a mild psychostimulant profile without euphoria or subjective drug effects. A phase 2 trial in depression reported a positive MADRS result, but only in a company press release; two phase 3 trials began in 2025.