Levodopa absorption profile in Parkinson's disease: Evidence to indicate qualitative difference from the control

In this study the authors report levodopa absorption profiles in eight patients with early stage Parkinson's disease (PD) and in eight age-matched normal control (NC) subjects; the gastric emptying time (GET) was studied simultaneously. Patients with PD showed a significantly higher peak plasma levodopa concentration, however, no significant difference in the GET was present between the two groups; therefore, the higher plasma levodopa peak could not be ascribed to the difference in the GET. In the NC subjects, plasma peak levodopa level was positively correlated with the GET, however, an inverse correlation was observed in the PD patients, suggesting the presence of a qualitative difference in the levodopa absorption mechanism between early PD and the normal population. Enhanced levodopa absorption may be a useful early marker for PD.