Effect of age on the pharmacokinetics of oral levodopa in patients with Parkinson's disease.
The influence of age on the kinetics of a standard oral dose of levodopa administered with an inhibitor of peripheral dopa decarboxylase enzymes (benserazide) has been evaluated in 40 patients with Parkinson's disease (age 34-78 y) on chronic therapy. They were divided into 2 groups, on the basis of age below (21 patients, Group A) or above (19 patients, Group B) 65 y. The area under the plasma concentration-time curve (AUC) of levodopa was significantly greater in the older group (547 versus 428 mumol.l-1.min in Group B), coupled with a reduced apparent oral clearance (8.1 versus 10.7 ml.min-1.kg-1) and a longer plasma elimination half-life (67.6 versus 54.6 min). The age of the patients was positively correlated with the AUC of levodopa (r = 0.474) and its plasma elimination half-life (r = 0.391), and was negatively correlated with clearance (r = -0.489). The findings confirm previous data on volunteers that showed a reduction in the systemic clearance of levodopa due to age, which would probably account for the finding of a greater AUC of levodopa in older patients. The observed, age-mediated differences in levodopa pharmacokinetics, albeit statistically significant, were moderate and were likely to be of only minor importance for the dosing schedule.
Contin
M
M
Institute of Neurology, University of Bologna, Italy.
Riva
R
R
Martinelli
P
P
Albani
F
F
Baruzzi
A
A
D000284:Administration, Oral; D000328:Adult; D000367:Age Factors; D000368:Aged; D005260:Female; D006801:Humans; D007980:Levodopa / Q000008:administration & dosage / Q000493:pharmacokinetics*; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000378:metabolism*
D007980:Levodopa