Stability indicating methods for the determination of cefpodoxime proxetil in the presence of its acid and alkaline degradation products

Four different, accurate, sensitive and reproducible stability- indicating methods for the determination of cefpodoxime proxetil (CPD) in the presence of its acid and alkaline degradation products are presented. The first method is based on derivative spectrophotometry. Second derivative spectrophotometry was applied where CPD was determined at 261 nm in the presence of its acid degradation product and also third derivative spectrophotometry was applied where CPD was determined at 282 nm in the presence of its alkaline degradation product. The second method is based on the first derivative of ratio spectrophotometry (1DD) of CPD at 215 nm and 255 nm in the presence of its acid degradation product and at 243 nm in the presence of its alkaline degradation product. The third method is ratio subtraction spectrophotometry where the drug is determined at 232 nm in laboratory prepared mixtures of CPD and its acid or alkaline degradation product. Calibration graphs were established for 4.0-40.0 μg/ml for CPD determination by the three spectrophotometric methods. The fourth method is an isocratic reversed -phase HPLC procedure, a Zorbax C8 column was used to separate CPD from its acid and alkaline degradation product using acetonitrile: water: triethylamine (60:40:1, v/v/v) as a mobile phase and detection at 232 nm. The suggested procedures were successfully applied for the analysis of CPD in bulk powder and in pharmaceutical preparations. The results obtained by applying the proposed methods were statistically analyzed and compared with those obtained by the official method.