title: Decreased efficacy of levodopa with carbidopa in parkinsonian patients after adrenal-to-caudate implants.
abstract: We studied 6 parkinsonian patients 6 weeks after unilateral adrenal-to-caudate implants. We withheld medications the night before each of 2 study days and gave the patients a single test dose of either a combination of levodopa and carbidopa, or levodopa alone in double-blind random order. We administered the modified Columbia scale, objective measurements of rigidity and movement velocity, and the pegboard test at regular intervals after the single test dose. The results revealed that the improvements in performance recorded by the Columbia scale and the pegboard test were significantly less on the side contralateral to the operation when patients received carbidopa, whereas there was no significant difference in performance between the 2 observations on the ipsilateral side. Carbidopa apparently crossed the disrupted blood-brain barrier and lowered the efficacy of levodopa.
authors.affiliation: Department of Medicine, University of British Columbia, Vancouver, Canada.
authors.forename: J K
authors.initials: JK
authors.lastname: Tsui
authors.forename: R F
authors.initials: RF
authors.lastname: Peppard
authors.forename: K C
authors.initials: KC
authors.lastname: Petruk
authors.forename: G
authors.initials: G
authors.lastname: Allen
authors.forename: R S
authors.initials: RS
authors.lastname: Burns
authors.forename: D B
authors.initials: DB
authors.lastname: Calne
mesh_terms: D000313:Adrenal Medulla / Q000166:cytology / Q000637:transplantation*; D000328:Adult; D002230:Carbidopa / Q000008:administration & dosage*; D003342:Corpus Striatum / Q000187:drug effects / Q000601:surgery*; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D007980:Levodopa / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000188:drug therapy* / Q000503:physiopathology / Q000601:surgery; D011597:Psychomotor Performance / Q000187:drug effects; D011897:Random Allocation
chemical_list: D007980:Levodopa; D002230:Carbidopa