Rapid determination of lamivudine in human plasma by high-performance liquid chromatography

A simple and rapid high-performance liquid chromatographic method with spectrophotometric detection was developed for the determination of lamivudine in human plasma. Sample preparation was accomplished through protein precipitation with acetonitrile followed by aqueous phase separation using dichloromethane. Lamivudine and the internal standard acyclovir were well separated from endogenous plasma peaks on a Chromolith RP-18e column under isocratic elution with 50 mM sodium dihydrogen phosphate-triethylamine (996:4, v/v), pH 3.2 at 20 °C. Total run time at a flow-rate of 1.5 ml/min was less than 5 min. Detection was made at 278 nm. The method was specific and sensitive, with a lower quantification limit of 40 ng/ml and a detection limit of 10 ng/ml. The absolute recovery was 97.7%, while the within- and between-day coefficient of variation and percent error values of the assay method were all less than 7%. The linearity was assessed in the range of 40-2560 in plasma, with a correlation coefficient of greater than 0.999. The method was successfully applied to a bioequivalence study in healthy volunteers.