Validation of high-performance liquid chromatographic-mass spectrometric method for the analysis of lidocaine in human plasma

A sensitive and simple liquid chromatography-tandem mass spectrometry method is developed and validated for the determination of lidocaine in human plasma. Bupivacaine is used as an internal standard, and the plasma extraction is performed by a simple liquid-liquid extraction. The limit of quantitation (LOQ) is 0.5 ng/mL with a signal-to-noise ratio greater than 5. The calibration curve is linear from 0.5 to 250 ng/mL with an r2 greater than 0.99. The coefficients of variation for within- and between-assay imprecision, including LOQ, are < or = 13% and < or = 8%, respectively. The percentage of inaccuracy for within- and between-assay, including LOQ, are < or = 9% and < or = 5%, respectively. The absolute recovery of lidocaine and bupivacaine are greater than 84% and 82%, respectively. The higher sensitivity and accuracy of this method allow the measurement of low concentrations of lidocaine in plasma from a clinical study of topically applied lidocaine in healthy subjects.