Early morning akinesia in Parkinson's disease: effect of standard carbidopa/levodopa and sustained-release carbidopa/levodopa.

We examined the effects of supplemental standard carbidopa/levodopa (Std-L) on early morning akinesia in patients with Parkinson's disease (PD) who were being treated with sustained-release carbidopa/levodopa (L-CR). We compared plasma dopa levels and clinical response in 15 PD patients after a dose of Std-L and L-CR (2 hours later) and after a dose of L-CR and placebo in a double-blind, placebo-controlled, crossover study. Plasma dopa levels, total motor score, walking time, and finger tapping time were assessed every 15 minutes for the first 2 hours and then every 30 minutes for the next 3 hours. The time of onset in clinical benefit was significantly earlier with Std-L (47 minutes, range 15 to 75 minutes) as the first dose as compared with L-CR (58 minutes, range 30 to 105 minutes). Similarly, there was a significant difference in the peak plasma dopa levels (Cmax) and the time to reach peak plasma dopa levels (Tmax) with administration of Std-L (Tmax 36 minutes; Cmax 1,501 micrograms/ml) as compared with L-CR (Tmax 111 minutes, Cmax 1,260 micrograms/ml). There was no significant difference in dyskinesias between the two treatment arms. An initial morning dose of Std-L alleviates the problem of delayed-onset clinical response that commonly occurs with L-CR.