title: L-dopa pharmacokinetics studied with microdialysis in patients with Parkinson's disease and a history of malignant melanoma.
abstract: OBJECTIVE
  The pharmacokinetics of free L-dopa in blood and tissue of five parkinsonian patients with malignant melanoma was studied with microdialysis. In one case the effect of L-dopa treatment on 5-S-cysteinyldopa and the melanoma was studied. Gastric emptying and its effects on free L-dopa in blood were also investigated in one of the patients.
  
  
  METHODS
  Five patients were given 100 mg L-dopa with 25 mg benserazide. Blood and dialysates from the circulation and fatty tissue were collected for analysis. [13C]-Octanoic breath test was used for analyzing gastric half-emptying time.
  
  
  RESULTS
  Four of the patients had similar pharmacokinetic patterns for L-dopa and a significant (P < 0.05) increase of serum 5-S-cysteinyldopa occurring 30 min after L-dopa intake. Delayed L-dopa peaks and slow gastric half-emptying time were found in 1 patient. A dose-dependent increase of 5-S-cysteinyldopa occurred but no melanoma metastases were seen during long-term L-dopa therapy.
  
  
  CONCLUSIONS
  L-dopa therapy increases 5-S-cysteinyldopa levels but does not seem to cause progress of melanomas. Gastric emptying impacts L-dopa pharmacokinetics.
authors.affiliation: Department of Clinical Chemistry, University Hospital, Linköping, Sweden.
authors.forename: N
authors.initials: N
authors.lastname: Dizdar
authors.forename: A K
authors.initials: AK
authors.lastname: Granérus
authors.forename: U
authors.initials: U
authors.lastname: Hannestad
authors.forename: A
authors.initials: A
authors.lastname: Kullman
authors.forename: A
authors.initials: A
authors.lastname: Ljungdahl
authors.forename: J E
authors.initials: JE
authors.lastname: Olsson
authors.forename: B
authors.initials: B
authors.lastname: Kågedal
mesh_terms: D000368:Aged; D000978:Antiparkinson Agents / Q000493:pharmacokinetics / Q000627:therapeutic use; D001545:Benserazide / Q000493:pharmacokinetics / Q000627:therapeutic use; D005260:Female; D006801:Humans; D007980:Levodopa / Q000493:pharmacokinetics* / Q000627:therapeutic use; D008297:Male; D008545:Melanoma / Q000150:complications*; D017551:Microdialysis; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications / Q000188:drug therapy*; D012878:Skin Neoplasms / Q000150:complications*
chemical_list: D000978:Antiparkinson Agents; D007980:Levodopa; D001545:Benserazide