Development Using Response Surface Methodology and Validation of a Stability-Indicating RP-HPLC Method for Simultaneous Estimation of Azilsartan Medoxomil and Chlorthalidone in Solid Dosage Form

摘要

A stability-indicating reversed-phase high-performance liquid chromatography method using a photodiode array detector has been developed for simultaneous estimation of chlorthalidone (CLR) and azilsartan medoxomil (AZL) in combined solid dosage form. The method was developed based on statistical design of experiments (DoE) followed by optimization using the response surface methodology. Separation was achieved on a double end-capped C-18 column (150 mm x 4 mm, 5 A mu m). The effects of % acetonitrile (v/v) and buffer salt concentrations on the retention time of the two drugs and on their resolution were investigated and optimized. A robust design space was created by the overlay contour plot method. The optimum chromatographic condition within the design space was found to be isocratic mobile phase consisting of 10 mM Tris(hydroxymethyl)aminomethane buffer (pH 7.7) and acetonitrile at ratio of 60:40 (v/v) with flow rate of 1 mL min(-1) for 7 min. The retention times of CLR and AZL were found to be 2.6 and 4.9 min, respectively. The method was validated according to International Conference on Harmonization (ICH) and Food and Drug Administration (FDA) guidelines, and various validation parameters were determined. Forced degradation studies were also carried out in acid, base, oxidation, and reduction media with a view to establishing the specificity and stability-indicating property. The practical applicability of the method was confirmed by determining CLR and AZL in combined dosage form. This reliable and validated stability-indicating method for simultaneous estimation of CLR and AZL is available for routine analysis in the pharmaceutical industry as well as research laboratories.