Applications of New Validated RP-HPLC Method for Determination of Indomethacin and its Hydrolytic Degradants using Sodium Acetate Buffer

Objective: A New RP-HPLC method for estimation of indomethacin and its two degradant impurities 4-chlorobenzoic acid, 5-methoxy-2-methyl-indoleacetic acid was developed and validated as per ICH guidelines. Background: This new method is not only capable of identifying and quantifying the impurities but also can be used for the assay of indomethacin in marketed capsule formulations. Methods: The chromatographic conditions were optimized using Zorbax Eclipse Plus C18, 3.5 μm (4.6 mm × 100 mm) column with methanol: acetonitrile: 10 mM sodium acetate buffer pH 3, 10:50:40% v/v as the mobile phase at the flow rate of 1 ml/min and detection was carried out using UV-Visible PDA detector at 254 nm. Results: The method was linear over concentration range of 25-70 μg/ml for indomethacin, 0.25-2 μg/ml for 4-chlorobenzoic acid and 0.25- 2 μg/ml for 5-methoxy-2-methyl-indoleacetic acid. The developed method was validated as per the ICH guidelines for linearity, accuracy, precision, limit of detection, limit of quantification, robustness and specificity for indomethacin and its impurities.