Comparison of orally dissolving carbidopa/levodopa (Parcopa) to conventional oral carbidopa/levodopa: A single‐dose, double‐blind, double‐dummy, placebo‐controlled, crossover trial

Levodopa use in fluctuating Parkinson's disease (PD) is complicated by an inconsistent and prolonged onset to clinical improvement. An orally dissolved carbidopa/levodopa (OD C/L) preparation (Parcopa UCB Pharma) is available in the United States. This offers potential advantages to shorten the duration from ingestion to clinical improvement. Surprisingly, this has never been clinically assessed. We tested 20 patients with fluctuating PD and a Unified Parkinson's Disease Rating Scale (UPDRS) "off" motor score of ≥ 25 in a 2-day, single-dose, double-blind, double-dummy, crossover study. Patients arrived in the morning in the practically defined "off" state and were randomly assigned to receive identical doses of either oral C/L and OD placebo or OD C/L and oral C/L placebo on 1st day and the reverse combination on a 2nd day. After training, patients underwent bilateral hand tapping at baseline and every 5 minutes for 60 minutes after dose ingestion. Stride length (SL) was recorded at 5-minute intervals with an ambulatory gait monitor. Patients identified their subjective latency to "on" and noted drug preferences and adverse events. They also underwent a UPDRS motor examination at baseline and 60 minutes after dose. Twenty subjects [15 male, age 68.7 (9.7), PD duration 13.4 (6.8)] completed. There were no significant group differences in tapping speed, subjective time to "on," latency of increased SL, or overall preference. However, all trends did favor OD C/L. Adverse events were similar. This small pilot study did not show significant group differences favoring OD C/L; however, larger studies may be justified, and individual patients may benefit.