Benefits of monitoring plasma levodopa in Parkinson's disease patients with drug-induced chorea.

We studied the temporal patterns of chorea and plasma levodopa profiles in 30 patients with Parkinson's disease whose motor fluctuations were difficult to characterize and treat on the basis of observation alone. We were able to determine whether chorea was associated with high levodopa concentrations or low levodopa concentrations or both. We found the following patterns of levodopa-associated chorea: chorea due to inadequate levodopa levels, chorea due to biphasic levodopa absorption, chorea associated with either rapid or slow levodopa absorption, and chorea due to long-duration levodopa absorption mimicking a sustained-release preparation. Seven patients benefited after their dosing schedules were rearranged as a result of information gained from monitoring. We conclude that any patient with levodopa-associated chorea who cannot be regulated on the basis of observation alone should be studied with simultaneous plasma levodopa measurements and clinical monitoring to detect an unusual plasma levodopa pattern that may be improved by adjustment of dosing schedule.