Validation of high-performance liquid chromatography methods for determination of zidovudine, stavudine, lamivudine and indinavir in human plasma.

OBJECTIVE: Simple methods for the determination of zidovudine (AZT), stavudine (d4T), lamivudine (3TC) and indinavir (INV) in human plasma by reversed-phase liquid chromatography (HPLC) with UV detection were described and validated. METHOD: Solid-liquid extraction procedures were applied to the samples prior to analysis. Chromatography was performed on a C-18 analytical columns and the retention time ranged from 6.8 to 8.0 min for stavudine, 7.5 to 9.0 min for lamivudine, 11.2 to 11.9 min for zidovudine and indinavir. Four methods were validated for specificity, inter-and intra-assay precision and accuracy, absolute recovery and stability. RESULTS: Analytical curve ranged from 10-1600 ng/ml for stavudine, 50-3200 ng/ml for lamivudine, 0.05-5.0 microg/ml for zidovudine and 0.1-10.0 microg/ml for indinavir. Analytes stability during sampling processing and storage were established. Extraction recoveries are higher than 89% for all formulations. CONCLUSIONS: These methods proved to be simple, accurate and precise, and are currently in use in our laboratory for the quantitative analysis of antiretrovirals products in plasma, and for further pharmacokinetics and bioequivalence studies.

Bioequivalence study of two nevirapine tablet formulations in human-immunodeficiency-virus-infected patients.

OBJECTIVE: The present study describes the determination of the bioequivalence of two different nevirapine tablet formulations (nevirapine tablets 200 mg, Novatec, as the test formulation vs. viramune tablets 200 mg, Boehringer Ingelheim, as the reference formulation). METHOD: A single 200 mg oral dose of each preparation was administered to 11 human immunodeficiency virus (HIV)-infected patients volunteers and their bioequivalence was assessed by comparing the both plasma nevirapine concentrations-time curves and others pharmacokinetic parameters. RESULTS: The pharmacokinetic parameters obtained for each formulation were the area under the time-concentration curve from 0 to 12 h (AUC(0-12)) and from 0 to infinity (AUC(0-infinite)), maximum concentration (C(max)), and the time at which it occurred (T(max)). These parameters were determined by high-performance liquid chromatography (HPLC). No significant differences were observed in these parameters. The 90% confident interval for the ratio of means for the lnAUC(0-12 T/R) (0.92-1.10), lnAUC(0-infinite T/R) (0.86-1.17) and lnC(max T/R) (0.71-1.38) are within the guideline range of bioequivalence (0.80 to 1.25 and 0.70 to 1.43). For T(max) the mean of test formulation is in the range 2.64 +/- 0.53 h. CONCLUSIONS: The results show that the formulations were bioequivalent in the extent and in the rate of absorption.