amantadine hydrochloride

An antiparkinsonian drug that acts by increasing the activity of dopamine in the brain. It provides moderate relief of symptoms but tolerance to its effect may develop. Amantadine is also an antiviral drug that acts by inhibiting viral replication; it is used particularly in the prevention and treatment of influenza type A₂. It is available, on prescription only, as capsules or a syrup.

Side effects:
include nervousness, inability to concentrate, insomnia, dizziness, and (rarely) convulsions and hallucinations; nausea and loss of appetite may also occur.

Precautions:
amantadine should be used with caution in people who have liver or kidney disease, congestive heart disease, or states of confusion or hallucination. It should not be taken by people with epilepsy or a history of peptic ulcers or by women who are pregnant or breastfeeding. Withdrawal of the drug at the end of treatment should be gradual.

Interactions with other drugs:

Antipsychotics: extrapyramidal reactions can occur.
Memantine increases the risk of adverse effects on the central nervous system, and these two drugs should not be used together.
Methyldopa extrapyramidal reactions can occur.

Proprietary preparations:
Symmetrel; Lysovir (capsules).

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