A simultaneous method for quantitative determination of lamivudine and zidovudine in human plasma by using tandem mass spectrometry and its application to pharmacokinetic studies

A method employing high performance liquid chromatography with tandem mass spectrometry has been developed and validated for the simultaneous determination of clinically significant levels of lamivudine and zidovudine in human plasma. Emtricitabine & didanosine were used as internal standards for lamivudine and zidovudine respectively. The method involves sample preparation with solid-phase extraction technique with typical mass detection. The calibration range was 1.00 - 3507.87 ng/mL for lamivudine and 1.00 – 3502.29 ng/mL for zidovudine. An aliquot of 100μL of plasma was used for solid phase extraction technique. An isocratic mobile phase consisting of 0.1% formic acid in water and methanol (20:80; v/v) was used in the method. Chromatographic separation was achieved on Discovery C18 column over a run time of 2.5 minutes. The molecular ion Q1 & product ion Q3 transitions were found to be 230.0 →112.1, 268.1 →127.1, 248.2 →130.1 and 237.0 →137.0 for lamivudine, zidovudine, emtricitabine and didanosine respectively. The pharmacokinetic parameters for lamivudine were Tmax – 1.6 Hours, Cmax – 2031.8 ng/mL, T1/2 – 5.8 Hours, AUC (0-T) – 12371.4 ng.hrs/mL and AUC (0-∞) – 12552.3 ng.hrs/mL & for zidovudine were Tmax – 0.8 Hours, Cmax – 1786.3 ng/mL, T1/2 – 2.2 Hours, AUC (0-T) – 3244.3 ng.hrs/mL and AUC (0-∞) – 3250.9 ng.hrs/mL. The proposed assay method was found to be acceptable to a pharmacokinetic study in human volunteers.
Author(s): Nagamalleswara Rao K., Venkata Kumar Chb, Madhuri K., Anil Kumar Ch and Satyanarayana P. V. V.

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