Pharmacokinetics of levodopa in patients with Parkinson disease and motor fluctuations depending on the presence of Helicobacter pylori infection

According to recent investigations, the eradication of Helicobacter pylori (H. pylori) may influence levodopa (LD) pharmacokinetics (PK) and improve the motor function of infected patients with Parkinson disease (PD). The aim of this study was to compare PK of LD and its metabolite 3-O-methyldopa (3-OMD), between H. pylori-positive (HP+) and -negative (HP-) patients with PD and motor fluctuations. Patients with the clinical diagnosis of PD, under stable LD therapy, reporting daily motor fluctuations and who had no history of previous eradication treatment were screened for the H. pylori infection with an antigen stool test. Two groups of patients-bacteria-infected and noninfected-matched demographically and clinically, were selected for the examination of PK values. Blood samples were collected after morning oral LD dose. Noncompartmental PK parameters were computed from the LD and 3-OMD plasma concentration-time data. Interindividual variability was seen in LD absorption curve in both groups. There were no clinically significant differences in PK parameters of LD and 3-OMD. Changes of small magnitude but with possible clinical impact were found according to tmax and Cmax that tended to be lower in HP- patients and AUC0-t that was larger in the HP+ group. The Cmax value of 3-OMD was almost identical in both groups. The HP- group had smaller AUC0-∞t of 3-OMD. The H. pylori infection in PD patients with motor fluctuations, despite not significantly influencing PK parameters of LD and 3-OMD, may still have important clinical implications.