Dopaminergic agent / NMDA receptor antagonist
Enhances dopamine release and blocks NMDA glutamate receptors, which may improve motor symptoms and reduce excitotoxicity
Parkinson’s disease (PD), drug-induced extrapyramidal symptom
Fatigue in multiple sclerosis (MS), post-stroke apathy, post-stroke fatigue, agitation and aggression in traumatic brain injury (TBI), fatigue in TBI, catatonia (second-line)
Immediate-release tablets, extended-release capsules
Start 100 mg p.o. daily, titrate up to 100–300 mg/day as tolerated
100–300 mg/day
Half-life approximately 10–14 hours; renally excreted unchanged
Insomnia, nausea, dry mouth, dizziness, hallucinations, livedo reticularis
Psychosis, seizures (rare)
Monitor renal function, neuropsychiatric symptoms, and skin changes
None
Amantadine should be used cautiously in elderly patients and those with cognitive impairment due to risk of confusion and hallucinations. In TBI or post-stroke populations, it may improve apathy, fatigue, or aggression, though monitoring for behavioral disinhibition is warranted. Dose reductions are necessary in renal impairment.