DDC and Parkinson disease: This multicenter longitudinal study aimed to investigate sex-related differences in levodopa pharmacokinetics in levodopa-naïve PD patients, and to evaluate relationships with levodopa-related complications.<h4>Methods</h4>After a single dose of levodopa/DOPA-decarboxylase inhibitor, blood samples were collected at baseline and at two-year follow-up to measure pharmacokinetic parameters using UHPLC-MS.