Simultaneous determination of levodopa, carbidopa, entacapone, tolcapone, 3-O-methyldopa and dopamine in human plasma by an HPLC–MS/MS method

Abstract

Background: In this study, we developed and validated a HPLC–MS/MS method capable of simultaneously determining levodopa, carbidopa, entacapone, tolcapone, 3-O-methyldopa and dopamine in human plasma. Results & methodology: Chromatographic separation was achieved using a C8 column with a mobile phase consisting of a gradient of water and acetonitrile:methanol (90:10 v/v), both containing 0.1% formic acid. The developed method was selective, sensitive (LD <7.0 ng ml-1), linear (r > 0.99), precise (RSD < 11.3%), accurate (RE < 11.8%) and free of residual and matrix effects. The developed method was successfully applied in plasma patients with Parkinson's disease using Stalevo®. Conclusion: The new method can be used for the clinical monitoring of these substances and applied to adjustments in drug dosages.