Development and Validation of Stability Indicating RP-HPLC Method For Estimation of Sildenafil Citrate and Estradiol Valerate In Tablet

A simple, precise and accurate stability indicating RP-HPLC method has been developed and subsequently validated for the simultaneous estimation of Sildenafil citrate and Estradiol valerate in bulk and pharmaceutical formulation. The separation was carried out using C18 column (150mm x 4.6mm, 5μm), mixture of acetonitrile and water 80:20 % v/v as a mobile phase with a flow rate of 1 ml/min and the effluent was monitored at 290 nm using PDA detector. The retention time of Sildenafil citrate and Estradiol valerate were 2.55 min and 5.56 min respectively. The method is linear over the range of 125 - 750 μg/ml and 5 - 30 μg/ml for Sildenafil citrate and Estradiol valerate respectively. The method was found to be precise, accurate and specific during the study. The percentage assay was found to be 100.68 % and 99.58 % for Sildenafil citrate and Estradiol valerate respectively from the tablet formulation. Sildenafil citrate and Estradiol valerate were subjected to stress condition to check the degradation behaviour of them. The drugs undergo degradation under acidic, basic, oxidative and thermal condition. The proposed method enables rapid quantification and simultaneous analysis of both drugs from commercial formulations without any interference of excipients. So, the method can be used for routine analysis of Sildenafil citrate and Estradiol valerate in combined tablet formulation.