Four-year treatment of patients with parkinsonism using amantadine alone or with levodopa.

Half of 94 parkinsonian patients improved on amantadine therapy during acute double-blind trials. In a four-year follow-up, amantadine given alone or added to a stable dose of levodopa had its greatest effect in the first month and helped few patients after six months. Levodopa either alone or added to a stable dose of amantadine had a beneficial effect lasting three years or more. The side-effects of edema and livido reticularis occurred twice as often in women. Confusion and hallucinations appeared sooner on a regimen of 300 mg of amantadine a day, but the ultimate incidence was the same on 200 mg a day. Withdrawal effects from amantadine are no less frequent or serious than from other antiparkinson medications and are not evidence that amantadine is still helping the patient. Considering the years of exposure, the morbidity and mortality do not indicate any risks peculiar to amantadine. Our mortality in all groups combined was 2.4 times that of the age- and sex-matched United States population.