Stability Indicating RP-HPLC Method for the Simultaneous Estimation of Pyrimethamine and Sulphadoxine in Bulk and Tablet Dosage Form

A stability indicating simple, selective, accurate high Performance Liquid Chromatographic (HPLC) method was developed and validated for the combined tablet formulation of pyrimethamine & sulphadoxine. Chromatographic separation was optimized by gradient HPLC on a C18 column [Inertsil Silica, 250 x 4.6 mm, 5] utilizing a mobile phase of potassium dihydrogen phosphate and acetonitrile taken in the ratio 70:30 at a flow rate of 1.0 ml/min with UV detection at 221nm. The retention time of pyrimethamine and sulphadoxine was 2.77 and 6.57 min respectively. The developed method was validated in terms of accuracy, precision, linearity, limit of detection, limit of quantitation, robustness and stress degradation studies. Validation of the method was done in accordance with ICH guidelines for the assay of active ingredients. Thus validated method can be recommended for the routine laboratory analysis.