Determination of lamivudine in human plasma by RP-HPLC and its application to bioequivalence research

AIM:To develop a HPLC method for the determination of lamivudine in plasma and study the pharmacokinetics and relative bioavailability of domestic lamivudine tablet in Chinese healthy volunteers.METHODS: A single oral dose(0.3 g) of test tablet(domestic) or reference tablet(imported) was given to each volunteer according to an open randomized crossover study.The concentrations in plasma were determined by RP-HPLC method.The prepared sample was separated on the column of Kromasil C18(250 mm×4.6 mm ID,5 μm),with the mobile phase consisting of methanol-25 mmol/L potassium dihydrogen phosphate(containing of 1% triethylamine pH 3.3)(10∶90) at a flow rate of 1 mL/min.The eluted peaks were detected by UV detector at 280 nm.The pharmacokinetic parameters and relative bioavailability were calculated by DAS 2.1.RESULTS:The calibration curve was linear in the range of 25-7500 μg/L(r=0.9992).The relative recoveries of low,medium and high concentration were within 100.09%-103.36%.The intra-batch and inter-batch RSD were less than 2.2% and 7.8%,respectively.The main pharmacokinetic parameters of lamivudine were as follows: Cmax were(2835±734) and(2868±726) μg/L;tmax were(1.15±0.60) and(1.05±0.78) h;t1/2 were(2.68±0.32) and(2.58±0.41) h;AUC0-14 h were(10994±1839) and(10593±1654) μg·L-1·h;AUC0-∞ were(11330±1908) and(10884±1734) μg·L-1·h for test and reference preparations,respectively.The relative bioavailability of test tablet was(104.80±15.56)%.CONCLUSION: The assay method is simple,sensitive,accurate and good enough to be used in pharmacokinetic study of lamivudine.The results of statistical analysis show that two preparations in research are bioequivalent.