Pharmacokinetics and effects of levodopa in advanced Parkinson's disease.
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.
Bredberg
E
E
Department of Biopharmaceutics and Pharmacokinetics, University of Uppsala, Sweden.
Tedroff
J
J
Aquilonius
S M
SM
Paalzow
L
L
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*
D007980:Levodopa