Simultaneous determination of l-dopa and its prodrug (S)-4-(2-acetamido-3-ethoxy-3-oxopropyl)-1,2-phenylene diacetate in rat plasma by high-performance liquid chromatography–tandem mass spectrometry and its application in a pharmacokinetic study

A sensitive, simple and rapid HPLC–MS/MS method has been developed and validated for the simultaneous determination of l-dopa and its prodrug (S)-4-(2-acetamido-3-ethoxy-3-oxopropyl)-1,2-phenylene diacetate (AEPD) in rat plasma in the present study. The analytes were separated on a C 18 column (5 μm, 2.1 mm × 150 mm) with a security guard C 18 column (5 μm, 4 mm × 20 mm) and a triple-quadrupole mass spectrometry equipped with an electrospray ionization (ESI) source was applied for detection. With α-methyldopa as internal standard, sample pretreatment involved in a one-step protein precipitation with 0.4 M perchloric acid. The method was linear over the concentration ranges of 50–5000 ng/ml for l-dopa and 12.5–2500 ng/ml for AEPD. The intra-day and inter-day relative standard deviations (RSD) were less than 15% and the relative errors (RE) were all within 15%. Finally, the method was successfully applied to support the pharmacokinetic study after l-dopa and its prodrug AEPD were orally administrated to the Sprague–Dawley rats, respectively.