Simultaneous stability-indicating HPLC method for the determination of cisapride, methylparaben and propylparaben in oral suspension

A simultaneous stability-indicating HPLC method for the determination of cisapride, methylparaben and propylparaben in oral suspensions has been developed and validated. Baseline separation was achieved on a C18 column at room temperature (25°C) by gradient elution with mobile phase consisting of solvent A: 10% v/v acetonitrile in 0.13% w/v sodium-1pentanesulfonate pH 8 and solvent B: acetonitrile. The gradient program was as follows: 0-5 min: 20 to 56% solvent B; 5-7 min: 56 to 85% solvent B; 7-10 min: 85% solvent B. The flow rate of mobile phase was 1.2 mL/min. The injection volume was 20 L. Detection and peak purity assessments were performed by photo-diode array detector set at 275 nm with scan mode in the range of 190-400 nm. The method was selective, accurate and precise. It provided chromatograms with good peak shape and acceptable resolutions of greater than 4.4 for all analytes including the degradation products formed in oral suspensions in about 8.5 min. All analyte peaks were pure. The accuracy of all analytes was in the range of 99.20-100.6%. The within-run and between-run relative standard deviations were less than 1.50%. The calibration curves for cisapride, methylparaben, and propylparaben were linear over the concentration range of 10.0-75.0 g/mL, 8.0-100.0 g/mL, and 0.8-10.0 g/mL, respectively with r greater than 0.999. This developed method was successfully applied to the stability study of cisapride, methylparaben and propylparaben in oral suspension formulations.