Decreased efficacy of levodopa with carbidopa in parkinsonian patients after adrenal-to-caudate implants

• Published in: Neurology Vol. 40; no. 5; p. 845
• Main Authors: Tsui, J K, Peppard, R F, Petruk, K C, Allen, G, Burns, R S, Calne, D B
• Format: Journal Article
• Language: English
• Published: United States 01-05-1990
• Subjects: Adrenal Medulla - cytology; Adrenal Medulla - transplantation; Adult; Carbidopa - administration & dosage; Corpus Striatum - drug effects; Corpus Striatum - surgery; Double-Blind Method; Drug Therapy, Combination; Female; Humans; Levodopa - administration & dosage; Male; Middle Aged; Neuropsychological Tests; Parkinson Disease - drug therapy; Parkinson Disease - physiopathology; Parkinson Disease - surgery; Psychomotor Performance - drug effects; Random Allocation
• ISSN: 0028-3878; 1526-632X
• DOI: 10.1212/wnl.40.5.845

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.