Development and validation of an LC–ESI–MS/MS method for simultaneous determination of levodopa, dopamine, L-α-methyldopa and 3-O-methyldopa in rat plasma

Abstract

Parkinson’s disease (PD) is a progressive degenerative disorder of the central nervous system. Levodopa (L-dopa), dopamine precursor is the most effective therapeutic drug for PD patients. Levodopa (LDP) and its three metabolites in rat plasma were determined using high performance liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS). Method validation was conducted in terms of linearity, accuracy, precision, recovery, specificity, limit of detection, limit of quantification and stability. Correlation coefficients (r ²) were above 0.9965. The intra-day accuracy values at LLOQ (low limit of quantification), LQC (low quality control), MQC (medium quality control) and HQC (high quality control) levels were 85.7–103.3, 96.5–105.1, 90.7–100.1 and 94.2–101.3 %, respectively. The inter-day accuracy values at LLOQ, LQC, MQC and HQC levels were 77.6–112.0, 91.1–109.3, 84.3–101.0 and 88.2–103.9 %, respectively. The coefficient of variation (RSD) values of both intra- and inter-day results were within 6.7 and 8.5 %, respectively. The recoveries (mean ± %SD) for LLOQ, LQC, MQC and HQC were 82.7 ± 3.7–113 ± 2.8 %, 86.6 ± 5.7–110.3±3.4 %, 90.9 ± 3.6–106 ± 6.5 and 89.7 ± 4.5–97.4 ± 6.7 %, respectively. The coefficient of variation (RSD) values of both intra- and inter-day results were within 6.7 and 8.5 %, respectively. The validated LC–MS/MS method was applied successfully to the measurement of LDP and its metabolites in the rat plasma samples.