The effect of exercise on pharmacokinetics and pharmacodynamics of levodopa

The aim of our study was to evaluate the influence of low-intensity exercise on levodopa absorption and levodopa motor effect. We studied the pharmacokinetics and pharmacodynamics of levodopa under resting conditions and under a workload of 50 watts for 2 hours on a cycle ergometer in 12 parkinsonian patients with predictable fluctuations of motor disability. The patients attended the hospital on both days in a provoked off state. After a baseline assessment of motor disability using the Columbia University rating scale (CURS scale) and a blood test for measurement of the baseline levodopa concentration in the plasma, 100 mg levodopa and 25 mg benserazide were administered as a single dose orally. Blood samples for measurement of the levodopa concentration in the plasma were taken, and motor assessments were conducted 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 significantly between both days. The mean levodopa concentration in plasma at half-maximal motor effect tended to be higher during exercise and indicated that the patients needed a higher levodopa concentration in plasma to achieve the half-maximal motor effect. The maximal levodopa concentration in plasma 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 absorption and a trend toward a deteriorated concentration-effect correlation.