Abstract

Stability-indicating methods for determination of sildenafil in presence of its degradation product

Author(s): MoatazA.Yehia, Mamdouh R.Rezk,MohamedA.El-Sayed,MohamedAbdel Kawy

Four different stability indicating assay methods were developed and validated for the determination of sildenafil in the presence of its degradation product. The first and second method was based on the derivative and derivative ratio spectrophotometric technique using methanol as a solvent. In the third method, we used TLC-densitometric technique using high performance thin-layer chromatography plates with a developing system consisting of chloroform: toluene: ethanol: acetic acid (3:3:4:0.1, by volume). The fourth method was a high performance liquid chromatography. Separation of sildenafilfrom its degradate using C18 column and a mobile phase consisting of acetonitrile: methanol: 0.05 M potassium di-hydrogen phosphate (v/v, pH 5.8): tri-ethyl amine, in the ratio of (45: 25: 30: 0.2, by volumes)at ambient temperature was achieved. The developed methods were successfully applied to the analysis of pharmaceutical formulations containing sildenafilwith excellent recoveries.