Validation of a stability indicating UPLC method for assay and impurity determination of diazepam in tablets

Abstract

Diazepam is a tranquilizer drug widely prescribed worldwide. Due to its increased use, quality control of its pharmaceutical dosage forms is needed to ensure their effectiveness and safety. Many methods have been proposed, but most are applicable to the determination of diazepam and its metabolites in blood plasma. In the present study we proposed a HPLC/UPLC conversion of analytical method described in the Brazilian Pharmacopoeia for quantitative determination of diazepam and its degradation products in tablets under isocratic conditions with a flow rate of 0.3 mL/min, a C18 chromatographic column 50mm x 2.1mm with 3 μM particle size conditioned at 30 ± 2°C. The mobile phase consisted of a mixture of methanol: acetonitrile: water (35:35:30), the injection volume was 1.4 μL and wavelength of 254 nm. Two works range were validated: assay (20 μg/mL) and impurities (2 μg/mL) and the selectivity, linearity, precision, accuracy, robustness and sample and standard stability solutions were. The tablets were subjected to different stress conditions, such as degradation by metal ions, thermal, photolytic, oxidative acid/alkali hydrolysis and exposure to moisture and checked his specificity. The validated method is indicative of stability, simple, rapid, reproducible and reliable and can be used in routine quality control laboratory.