Stability-indicating UPLC-MS/UV method for simultaneous determination of sildenafil citrate and dapoxetine hydrochloride from bulk and formulation

Abstract

The present work was focused on development of rapid, specific and novel stability-indicating ultra-performance liquid chromatographic method for simultaneous determination of sildenafil citrate and dapoxetine hydrochloride in bulk and formulation. The drugs were subjected to hydrolysis (acidic, alkaline and neutral), photolytic and thermal stress, as per International Conference on Harmonisation guidelines Q1A (R2). The identification of major stressed degradation products was performed using qudrupole electrospray ionization mass spectroscopy. Separation of drugs from their degradation products was achieved on acquity ultra-performance liquid chromatographic I class equipped with photodiode array detector. Acquity BEH Shield RP18 column was used with the gradient elution and detection wavelength of 294 nm. The method was found to be linear in the concentration range of 2.5-100 µg/ml for both sildenafil and dapoxetine hydrochloride. Limit of detection and quantitation was found to be 0.15-0.45 μg/ml and 0.1-0.3 μg/ml for sildenafil and dapoxetine, respectively. Moreover, the fragmentation pattern of both drugs was studied using ultra-high pressure liquid chromatography-tandem mass spectrometry. Sildenafil was found to be unstable under acidic condition while dapoxetine was found to be unstable under alkaline conditions.