Pharmacokinetic-pharmacodynamic crossover comparison of two levodopa extension strategies.

Controlled-release carbidopa and levodopa (CL-CR) and the combination of carbidopa, levodopa, and entacapone (CLE) are used for extending levodopa (L-dopa) effects. In a randomized, open-label crossover study of 17 PD subjects with wearing-off responses, we compared 8-hour L-dopa pharmacokinetics (PK) and clinical effects after two doses of CL-CR (50 and 200 mg, respectively) and CLE (37.7, 150, 200 mg, respectively).