Validation of an HPLC method for the determination of valdecoxib and its degradation product:: a mixture of α- and β-n-lactosyl sulfonamide anomers

An HPLC method has been developed for the separation of valdecoxib and a degradation product consisting of alpha and beta-N-lactosyl sulfonamide, i.e. alpha and beta anomers (SC-77852). Best results were achieved with a Chromolith Performance RP-18e column (100 mm x 4.6 mm), macropore size 2 pm, mesopore size 13 nm, with an eluent of methanol:water containing a 1% solution of TEA (36:64 v/v), pH 7.4 (adjusted with 85% orthophosphoric acid), at 22 degrees C. Detection was at 220 nm. The method was validated for its selectivity, linearity, precision (repeatability) and robustness. Quantitation and detection limits were determined for both valdecoxib and SC-77852. Method robustness was further evaluated by performing 2 3 full factorial design experiments. The final step, optimisation of the variables, was performed using response surface design. The validated method was used for assay of valdecoxib and SC77852 in Bextra((R)) film-coated tablets.