Development and validation of RP-HPLC method for sildenafil citrate in rat plasma-application to pharmacokinetic studies.

Sildenafil citrate (SIL) is used in the treatment of erectile dysfunction and other chronic disorders. For the pharmacokinetic investigation of SIL we developed a simple and sensitive method for the estimation of SIL in rat plasma by reverse phase high-performance liquid chromatography (RP-HPLC). The drug samples were extracted by liquid-liquid extraction with 300 μl of acetonitrile and 5 ml of diethyl ether. Chromatographic separation was achieved on C18 column using methanol:water (85:15 v/v) as mobile phase at a flow rate of 1 ml/min and UV detection at 230 nm. The retention time of SIL was found to be 4.0 min having a separation time less than 5 min. The developed method was validated for accuracy, precision, linearity and recovery. Linearity studies were found to be acceptable over the range of 0.1-6 μg/ml. The method was successfully applied for the analysis of rat plasma sample for the application in pharmacokinetic study, drug interaction, bioavailability and bioequivalence.