Effect of concomitant use of esomeprazole on levodopa pharmacokinetics and clinical symptoms in patients with Parkinson's disease.

Background: Proton pump inhibitors (PPIs), which inhibit gastric acid secretion, are frequently prescribed to patients with Parkinson's disease (PD). Levodopa, the gold-standard treatment for PD, demonstrates enhanced solubility in acidic environments. Although PPIs increase gastric pH and may affect levodopa absorption, the effect of concomitant PPI use on levodopa pharmacokinetics in patients with PD remains unknown. This study aimed to investigate the effect of the concomitant use of esomeprazole, a PPI, on the pharmacokinetics of levodopa and carbidopa and clinical symptoms in patients with PD.

Methods: We prospectively enrolled 40 patients with PD and compared the pharmacokinetics of levodopa and carbidopa and clinical symptoms before and two weeks after the concomitant use of esomeprazole.

Results: The plasma concentrations of levodopa 30 min after concomitant oral administration of levodopa and esomeprazole were significantly lower (4.92 ± 4.10 μmol/L) than those without concomitant esomeprazole use (6.26 ± 3.75 μmol/L; p = 0.027). The plasma concentrations of carbidopa showed no significant differences with respect to concomitant esomeprazole use. Significant elevation was recorded in all subscores of the Movement Disorder Society-sponsored revision of the Unified Parkinson's disease Rating Scale scores after concomitant use of esomeprazole. No significant differences were observed between Helicobacter pylori-negative and Helicobacter pylori-positive patients. Non-elderly patients (age ≤ 70 years) tended to be more susceptible to the effect of esomeprazole on levodopa pharmacokinetics and clinical symptoms.

Conclusions: The unnecessary use of PPIs should be avoided in patients with PD, especially in non-elderly patients, to improve absorption of levodopa.