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1
Service de Neurologie and
2
PET/Biomedical Cyclotron Unit, ULB-Hôpital Erasme, Brussels, Belgium.
a Address correspondence to this author at: Service de Neurologie, ULB-Hôpital Erasme, 808, route de Lennik, B-1070 Brussels, Belgium. Fax (322) 555-4701; e-mail sdethy{at}ulb.ac.be
We used in vitro microdialysis-HPLC to determine L-3,4-dihydroxyphenylalanine (L-DOPA) and its metabolites in plasma of patients with advanced Parkinson disease. Blood samples and clinical evaluations were obtained 0, 30, 60, 90, 120, and 150 min after oral administration of carbidopa/L-DOPA (25/100 mg, 12.5/125 mg, and 50/200 mg). In vitro recoveries for L-DOPA and metabolites ranged from 22% to 36%. Linear correlation was found between metabolite concentrations in the dialysate and in the surrounding medium. There was a significant positive correlation between L-DOPA dose and plasma concentration of L-DOPA and homovanillic acid (P <0.04). Clinical response was maximum 60 min after L-DOPA administration. Threshold L-DOPA plasma concentration averaged 7.74 ± 3.3 µmol/L. Motor effect is longer with the highest L-DOPA peak concentration (P <0.01). Microdialysis-HPLC is readily applicable, reproducible, and allows monitoring of plasma L-DOPA and metabolites in parkinsonian patients.
Key Words: indexing terms: Parkinson disease levodopa catecholamines
The following articles in journals at HighWire Press have cited this article:
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N. Dizdar, A. Kullman, B. Norlander, J.-E. Olsson, and B. Kagedal Human Pharmacokinetics of L-3,4-Dihydroxyphenylalanine Studied with Microdialysis Clin. Chem., October 1, 1999; 45(10): 1813 - 1820. [Abstract] [Full Text] [PDF] |
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G. M. d'Eril, R. Moratti, and E. Perucca Total and Non-Protein-bound Fractions of 3,4-Dihydroxyphenylalanine Clin. Chem., April 1, 1998; 44(4): 895 - 895. [Full Text] [PDF] |
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