Comparative study on pharmacokinetics and pharmacodynamics of levodopa/carbidopa versus levodopa/benserazide
Objective To study the pharmacokinetic and pharmacodynamic characteristics of compound levodopa/carbidopa(250 mg/25 mg)and levodopa/benserazide(200 mg/50 mg)in patients with Parkinson's disease(PD).Methods This experiment used a levodopa challenge test with a randomized crossover design.In the first week,20 PD patients orally received either 275 mg of compound levodopa/carbidopa or 250 mg of levodopa/benserazide on an empty stomach,and in the second week,they received the other treatment.The levodopa blood concentration was measured using high-performance liquid chromatography-tandem mass spectrometry,and motor symptoms were evaluated using the Movement Disorder Society-Unified Parkinson's Disease Rating Scale Ⅲ.Results Data from 17 patients in the compound levodopa/carbidopa group and 18 patients in the levodopa/benserazide group was included in the analysis.After administration,the Cmax values of compound levodopa/carbidopa and levodopa/benserazide groups were(3 563.76±1 003.06)and(3 642.44±1 192.70)ng·mL-1;the tmax values were(1.10±0.44)and(1.03±0.55)h;the t1/2 values were(1.52±0.15)and(1.68±0.27)h;the AUC0-t values were(7 625.19±1 706.85)and(5 846.07±1 191.16)ng·mL-1·h;the mean residence time(MRT)values were(2.39±0.361)and(2.14±0.37)h,respectively.There were no statistically significant differences in the Cmax,tmax,and t1/2 values between the two groups(all P>0.05).Compared with the levodopa/benserazide group,the compound levodopa/carbidopa group increased levodopa AUC and prolonged MRT(all P<0.05).The improvement in motor symptoms and levodopa blood concentration showed consistent trends at various time points in both groups.The compound levodopa/carbidopa group showed significantly better improvement in motor function at 6 and 8 hours after medication compared to the levodopa/benserazide group[(-10.82±8.91)points vs(-5.17±6.78)points,(-7.88±10.05)points vs(-2.11±4.84)points;both P<0.05].Conclusion The pharmacokinetic and pharmacodynamic characteristics of compound levodopa/carbidopa are similar to those of levodopa/benserazide.