The effect of exercise on pharmacokinetics and pharmacodynamics of levodopa

The aim of our study was to evaluate the influence of low-intensity exercis e on levodopa absorption and levodopa motor effect. We studied the pharmaco kinetics and pharmacodynamics of levodopa under resting conditions and unde r a workload of 50 watts for 2 hours on a cycle ergometer in 12 parkinsonia n patients with predictable fluctuations of motor disability. The patients attended the hospital on both days in a provoked off state. After a baselin e assessment of motor disability using the Columbia University rating scale (CURS scale) and a blood test for measurement of the baseline levodopa con centration in the plasma, 100 mg levodopa and 25 mg benserazide were admini stered as a single dose orally. Blood samples for measurement of the levodo pa concentration in the plasma were taken, and motor assessments were condu cted at 15-minute intervals for 240 minutes and at 30-minute intervals from 240 to 360 minutes. All patients were able to perform the exercise program . The baseline Columbia University rating scale score did not differ signif icantly between both days. The mean levodopa concentration in plasma at hal f-maximal motor effect tended to be higher juring exercise and indicated th at the patients needed a higher levodopa concentration in plasma to achieve the half-maximal motor effect. The maximal levodopa concentration in plasm a tended to be higher with exercise. Both trends did not reach statistical significance. In summary, there was not a negative or a positive net effect of exercise on pharmacokinetics and pharmacodynamics of levodopa. However, there were two counteracting trends: a trend toward better levodopa absorp tion and a trend toward a deteriorated concentration-effect correlation.