title: Rate of motor response to oral levodopa and the clinical progression of Parkinson's disease.
abstract: We investigated the relationship between the rate of motor response after a standard levodopa oral dose and drug dynamic variables and disease-related factors in 66 patients with Parkinson's disease. Time to maximum finger tapping effect was positively correlated with matched duration of levodopa dose response and fell from a median 120 minutes in patients at Hoehn and Yahr stage I and II to 60 minutes in stage IV patients (p < 0.001). The accelerated response to levodopa dose with the advancement of disease was also apparent as an increased steepness of the tapping effect versus time curve, with a shift from a hyperbolic to a sigmoid profile. The rate of motor response to oral levodopa may reflect the rate of dopamine interaction with the postsynaptic receptors, providing an indirect objective index of presynaptic dopaminergic homeostasis.
authors.affiliation: Institute of Neurology, University of Bologna, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Contin
authors.forename: R
authors.initials: R
authors.lastname: Riva
authors.forename: P
authors.initials: P
authors.lastname: Martinelli
authors.forename: E J
authors.initials: EJ
authors.lastname: Triggs
authors.forename: F
authors.initials: F
authors.lastname: Albani
authors.forename: A
authors.initials: A
authors.lastname: Baruzzi
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000978:Antiparkinson Agents / Q000627:therapeutic use; D018450:Disease Progression; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D007980:Levodopa / Q000097:blood / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000187:drug effects*; D010300:Parkinson Disease / Q000188:drug therapy* / Q000503:physiopathology*; D011930:Reaction Time; D012720:Severity of Illness Index; D016896:Treatment Outcome
chemical_list: D000978:Antiparkinson Agents; D007980:Levodopa