Validation of single isocratic HPLC method for the assay of valdecoxib and determination of metaisomer impurity

Abstract

A sensitive and accurate isocratic high-performance liquid chromagraphic method is developed for the determination of both metaisomer impurity and assay of valdecoxib drug substance. This method uses a Phenomenex Luna C18 (2) column, a mobile phase of 60:30:10 (v/v) 20mM NaH2PO4, methanol, and tetrahydrofuran, respectively, with UV detection. This method is validated and its stability-indicating capability is established by performing stress studies under acidic, basic, oxidation, light, humidity, and thermal conditions. Valdecoxib is well separated from its metaisomer impurity with a resolution of more than 2.0. The limit of detection of 0.007% is obtained for the metaisomer impurity, and the relative response factor is also determined. Repeatability is good, with a relative standard deviation of not more than 0.2% and 0.8% for the assay and impurity methods, respectively. A system suitability test is developed with acceptance criteria and the requirements are met throughout the method validation. The method is validated as robust to variations in chromatographic conditions.