BIOEQUIVALENCY OF SILDENAFIL CITRATE TABLET FORMULATIONS OF SAMAGRA AND KAMAGRA USING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

This study was designed to establish a simple and reliable assay method in clinical laboratory for determination of sildenafil citrate, in a plasma samples by using solid- phase extraction (SPE, C-18) method and high- performance liquid chromatography (HPLC). Solid phase extraction (SPE) was an efficient sample extraction with a recovery of about 91%. Sildenafil was found to have linear dynamic range of 0.0 - 500 ng/mL. Twenty healthy male volunteers with average age of 32 ± 12 years old received 50 mg of each of the two sildenafil formulations; (SDI, Samagra) and Kamagra (India). There was a one week wash out period between doses. The plasma were purified on SPE mini column and then, the drugs molecules were separated on reversed phase (250 x 4.6 mm i.d) C-18 column , using acetonitrle : 50 µM formic acid buffer pH (4.5) (15 : 85 v/v). The eluted drugs were monitored on UV set at 230 nm, with a detection limit of 5.0 ng/mL. Plasma concentration - time curve were monitored by HPLC over a period of 12 hours after administration of both the drugs. Maximum plasma sildenafil concentration Cmax for Samagra was (232+17.29 ng/mL) and Cmax for (Kamagra) India (228 ± 11.53 ng/mL), respectively. Both reach maximum concentrations of sildenafil at about 1 hour obtained from plasma concentration - time curve data. The results indicate no significant difference between the two formulations and therefore, both