Controlled-release levodopa/carbidopa. I. Sinemet CR3 treatment of response fluctuations in Parkinson's disease.

Eight Parkinson patients with response fluctuations completed an open-label trial of a controlled-release carbidopa/levodopa preparation (Sinemet CR3). At the end of 6 weeks, percent "on" time and mean interdose interval increased, the number of daily doses and "off" periods was decreased, and the variability of plasma levodopa levels and disability scores was reduced. However, response fluctuations continued to occur, day-to-day consistency was poor, and the bioavailability of levodopa appeared less than that of standard Sinemet. Overall benefit waned over the next 3 to 6 months. Oral controlled-release carbidopa/levodopa is capable of reducing fluctuations in plasma levodopa levels and clinical performance in Parkinson's disease. The response to this particular controlled-release formulation was suboptimal and unsustained.