Amantadine

Amantadine is a medication with antiviral and antiparkinsonian properties. It is an adamantane compound (1-adamantanamine) whose exact mechanism is not wholly understood. First developed in the 1960s and marketed for influenza A, it later gained use in neurology for its dopaminergic effects. It is available in oral forms and as generic drug.

Antiviral use: Amantadine was used to prevent and treat influenza A outbreaks due to its ability to block the M2 ion channel of the virus, hindering viral uncoating. Widespread resistance has reduced its usefulness; it is no longer routinely recommended for influenza; it is not effective against influenza B and many current strains.

Parkinson's disease use and mechanism: In Parkinson's disease, amantadine provides modest symptomatic relief, especially in early disease and for reducing levodopa-induced dyskinesias. The drug is thought to enhance dopaminergic transmission and act as an NMDA receptor antagonist, with additional anticholinergic effects contributing to symptom relief.

Safety and adverse effects: Common adverse effects include nausea, dizziness, insomnia, and dry mouth; livedo reticularis (a mottled skin condition) and ankle edema can occur. Confusion, agitation, or psychosis may develop, particularly in older patients. Cautions include kidney impairment, heart failure, epilepsy risk, and interactions with anticholinergic or sedating medicines; discontinuation recommended if severe psychiatric symptoms arise.