title: Coadministration of domperidone increases plasma levodopa concentration in patients with Parkinson disease.
abstract: OBJECTIVE
  The aim of this study was to examine the effects of the peripheral dopamine D2-receptor antagonist, domperidone, on the plasma kinetics of levodopa in patients with Parkinson disease (PD).
  
  
  METHODS
  In a randomized crossover design, 18 hospitalized patients with PD received a single dose of levodopa/benserazide, 100/25 mg, with or without domperidone, 10 mg, under fasting conditions. Plasma levodopa concentrations were determined up to 3 hours after dose administration.
  
  
  RESULTS
  Mean ± SEM levodopa maximum plasma concentration (Cmax) (14.1 ± 2.9 vs 9.7 ± 1.6 μmol/L; P < 0.01), plasma concentration at 30 min (C30 min) (13.7 ± 3.0 vs 8.1 ± 2.0 μmol/L; P < 0.01), and area under the plasma concentration-time curve from 0 to 3 hours (AUC0-3 hr) (15.9 ± 3.1 vs 12.1 ± 2.4 μmol/L · hour; P < 0.05) were significantly higher after coadministration of levodopa with domperidone compared to levodopa alone. Thus, domperidone increased levodopa Cmax and AUC0-3 hr by 1.5- and 1.3-fold, respectively. There were no exacerbations of PD by concomitant domperidone administration.
  
  
  CONCLUSIONS
  The results demonstrate that coadministration of domperidone increased the bioavailability of levodopa. This may be the reason for no exacerbation of PD in concomitant administration of domperidone, a dopamine D2-receptor blocker.
authors: Department of Neurology and Clinical Pharmacology, Ehime University Hospital and School of Medicine, Shitukawa Tohon Ehime, Japan. n-nishi@m.ehime-u.ac.jp
authors: Noriko
authors: N
authors: Nishikawa
authors: Masahiro
authors: M
authors: Nagai
authors: Tomoaki
authors: T
authors: Tsujii
authors: Hirotaka
authors: H
authors: Iwaki
authors: Hayato
authors: H
authors: Yabe
authors: Masahiro
authors: M
authors: Nomoto
mesh_terms: D000368:Aged; D001682:Biological Availability; D018592:Cross-Over Studies; D004294:Domperidone / Q000008:administration & dosage* / Q000097:blood*; D065127:Dopamine D2 Receptor Antagonists; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D007980:Levodopa / Q000008:administration & dosage* / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000097:blood* / Q000188:drug therapy*
chemical_list: D065127:Dopamine D2 Receptor Antagonists; D007980:Levodopa; D004294:Domperidone