Gastric emptying rate and the systemic availability of levodopa in the elderly parkinsonian patient.

The gastric emptying rate and systemic availability of levodopa, administered as a single oral dose, was studied in six elderly parkinsonian patients, five elderly nonparkinsonian subjects, and six young healthy volunteers. In both elderly groups, gastric emptying was slowed relative to the young healthy volunteers. The lack of significant differences in the plasma elimination half-life of levodopa among the three groups was accompanied by increased absorption of the drug in the elderly patient groups. These findings are discussed in relation to a possible age-related alteration in the activity of peripheral dopa decarboxylase in the elderly parkinsonian patients.