Development and Validation of Stability-Indicating RP-HPLC Method for the Simultaneous Determination of Tizanidine HCl and Meloxicam in Rabbit's Plasma

High-performance liquid chromatography (HPLC) is a widely used technique for the simultaneous detection and quantification of different drugs. The purpose of the current study was to develop a simple and cost-effective reversed-phase high-performance liquid chromatography (RP-HPLC) method for the simultaneous determination of tizanidine (TZN) HCl and meloxicam (MLX) in rabbitu0027s plasma. Assay of TZN and MLX was performed after extraction of drug from plasma by liquid–liquid extraction technique using methanol and diethyl ether as protein precipitants. Isocratic elution was performed in a Kromasil® C18 column (dimension, 250 × 4.60 mm; particle size, 5 μm) with mobile phase consisting of methanol–water (8:2). Orthophosphoric acid was used to adjust the pH of the mobile phase 3.0, and detection was done at 228 nm. Flow rate was 0.8 mL/min with ambient temperature and average operating pressure of 1400 psig. Retention time of TZN was 2.612 min and that of MLX was 6.960 min with a resolution of 3.18. Both drug...