AMANTADINE REDUCES LEVODOPA-INDUCED DYSKINESIAS IN PARKINSONIAN MONKEYS

The antidyskinetic potential of the glutamate NMDA receptor channel bl ocker amantadine was evaluated in four levodopa-primed parkinsonian mo nkeys using two differ ent regimens (1.25 or 2.5 mg/kg administered su bcutaneously twice daily for 3-6 days). When administered with a relat ively low dose of levodopa, amantadine produced a near-total suppressi on of choreiform dyskinesias and a substantial reduction in dystonic d yskinesias at the expense of a significant reduction in antiparkinsoni an response. With a high dose of levodopa, amantadine had a smaller bu t still significant effect on dyskinesias without altering the antipar kinsonian response. These results lend support to the view that glutam ate receptor-mediated mechanisms contribute to levodopa-induced dyskin esias. They also suggest that amantadine could alleviate such complica tions in parkinsonian patients, especially with careful dose optimizat ion.