Comparison of 200 mg retarded release levodopa/carbidopa – with 150 mg levodopa/carbidopa/entacapone application: pharmacokinetics and efficacy in patients with Parkinson’s disease

The interval of line tracing performance is more associated to basal ganglia function due to the dependence on bradykinesia and rigidity. The other component of this task, the precision of execution of complex movement sequences, is more related to attention. We compared the motor response after once dosing of 200 mg retarded release LD (levodopa)/CD (carbidopa) and of 150 mg LD/CD/EN (entacapone) by rating of motor symptoms, by measurement of LD- and 3-O-methyldopa (3-OMD) plasma concentrations and by the outcomes of a line tracing task. Thirteen treated patients with Parkinson's disease (PD) took one of the two tested LD formulations on two consecutive days under randomised, double blind, identical standardised conditions. No significant differences appeared regarding rated motor response and LD plasma concentrations, but 3-OMD only significantly went up after LD/CD intake. LD/CD/EN was superior to LD/CD regarding the attention related components of line tracing probably due to a hypothetically increased dopamine occurrence at the prefrontal cortex, which guides human behaviour.