title: Pharmacokinetics and effects of levodopa in advanced Parkinson's disease.
abstract: Five patients with severe Parkinson's disease were characterized with respect to their pharmacokinetic and pharmacodynamic responses to levodopa given: orally, intravenously (three different infusion rates) and intraduodenally. The best therapeutic infusion rate in the intravenous study was used for the intraduodenal infusion of levodopa. A lag time between plasma concentration and effect following oral administration was seen in three of the five patients and this disequilibrium was estimated as the rate constant Ke0 using model-independent analysis. The plasma concentration-effect relationship was similar for the three modes of administration and in all patients the therapeutic plasma concentration for full mobility was greater than 4-5 micrograms.ml-1. The disequilibrium half-life for development of effect after oral administration was calculated to be about 30 min. The patients remained clinically stable during the period of the intraduodenal infusion.
authors.affiliation: Department of Biopharmaceutics and Pharmacokinetics, University of Uppsala, Sweden.
authors.forename: E
authors.initials: E
authors.lastname: Bredberg
authors.forename: J
authors.initials: J
authors.lastname: Tedroff
authors.forename: S M
authors.initials: SM
authors.lastname: Aquilonius
authors.forename: L
authors.initials: L
authors.lastname: Paalzow
mesh_terms: D000284:Administration, Oral; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D007980:Levodopa / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000188:drug therapy / Q000378:metabolism*
chemical_list: D007980:Levodopa