NEW STABILITY INDICATING RP-LC METHOD FOR SIMULTANEOUS QUANTIFICATION OF RELATED IMPURITIES OF LAMIVUDINE, TENOFOVIR DISOPEOXIL FUMARATE AND NEVIRAPINE IN EXTENDED RELEASE TABLET DOSAGE FORMS

Abstract

The objective of the current study was to develop and validate precise, specific and stability-indicating reverse phase LC method for the simultaneous quantitative determination of Lamivudine, Tenofovir disoproxil fumarate and Nevirapine and their related impurities. The determination was done for extended release tablets dosage form where Tenofovir and Lamivudine are formulated into immediate release and Nevirapine into extended relase. The pharmaceutical formulation along with individual active ingredients was subjected to stress conditions of hydrolysis (acid and base), oxidation and thermal degradation as per International Conference on Harmonization (ICH) prescribed stress conditions to show the stability-indicating power of the method. It was found Tenofovir disoproxil fumarate is very sensitive to various stress conditions and readily degrades into Monoester impurity. The chromatographic conditions were optimized using an impurity-spiked solution and the samples generated from forced degradation studies. Regression analysis shows an r value (correlation coefficient) of greater than 0.997 for individual active drug substances and their all the related impurities. The chromatographic separation was achieved on a core shell technology C18 stationary phase. The method employed a linear gradient elution and the detection wavlength was set at 260 nm. The mobile phases consists of buffer and acetonitrile delivered at a flow rate of 0.8 mL·min–1. The stress samples were assayed against a qualified reference standard and the mass balance was found to be close to 98.5%. The developed RP-LC method was validated with respect to linearity, accuracy, precision and robustness