Stability-indicating HPLC-DAD method development, validation, and stress degradation studies for triamterene and xipamide in their combined tablet dosage form

Abstract

A simple stability-indicating high-performance liquid chromatography- diode array detection (HPLC-DAD) method has been developed for the simultaneous determination of triamterene (TRI) and xipamide (XIP) in presence of the degradation products generated in studies of forced decomposition. Drugs were subjected to stress by hydrolysis (acidic, alkaline, and neutral), oxidation, photolysis (254 and 365 nm), and dry and wet heat treatments. Degradation occurs under acidic and alkaline conditions (TRI only), oxidative stress (TRI and XIP), and by photolysis (XIP only), but both drugs were stable under other stress conditions investigated. Separation of the two drugs from all the degradant peaks was achieved within 11 min using C8 column (250 × 4.6 mm, 5 μm) and mobile phase consisting of acetonitrile and 0.05 M phosphate buffer adjusted to pH 4 delivered at a flow rate of 1 mL min-1 using gradient elution system. The drugs were quantified at 220 nm using photodiode array detector, based on peak area. Peak homogeneity of the two drugs was checked using diode array detector, and the purity angle was within the purity threshold limit in all of the stressed samples. The calibration graphs for each drug were rectilinear in the range of 0.2-50 and 0.1-20 μg mL-1 for TRI and XIP, respectively. The method was validated in compliance with International Conference on Harmonization (ICH) guidelines; in terms of linearity, accuracy, precision, robustness, limit of detection, and limit of quantitation. The proposed method was successfully applied for the determination of the investigated drugs in their tablet without interference from excipients with acceptable accuracy and precision; the label claim percentages were 100.23 ± 0.70% and 100.75 ± 1.11% for TRI and XIP, respectively.