HPLC-DAD stability indicating determination of pentoxyverine citrate. Application to degradation kinetics and assay of syrup dosage form

AbstractThe study describes the development, validation and application of a simple and reliable HPLC-DAD procedure for the stability-indicating determination of the cough suppressant drug pentoxyverine citrate (PTV). The method involved the use of Waters Symmetry C8 (3.9×150mm, 5μm) column with gradient elution of the mobile phase composed of 0.025M phosphoric acid and acetonitrile. The gradient elution started with 10% (by volume) acetonitrile, ramped up linearly to 60% in 10min then it was kept constant till the end of the run. The mobile phase was pumped at a flow rate of 1mL/min. The multiple wavelength detector was set at 210nm, and quantification of the analyte was based on measuring its peak area. Retention time for PTV was about 7.03min. Reliability and analytical performance of the proposed HPLC method was validated with respect to linearity, range, precision, accuracy, specificity, robustness, detection and quantification limits. Calibration curve of PTV was linear in the range 10–150μg/mL with correlation coefficient >0.9998. The drug was subjected to forced-degradation conditions of hydrolysis, oxidation and dry heat. The proposed method proved to be specific and stability-indicating by resolution of the drug from its forced-degradation products. The validated HPLC method was applied to the analysis of PTV in syrup form where it was successfully resolved from the pharmaceutical additives and quantified with recoveries not less than 97.7%. Moreover, the proposed method was utilized to investigate the kinetics of acidic and basic hydrolysis of PTV, and to derive its pH-rate of degradation profile in Britton–Robinson buffer within the pH range 2–12. Finally, the proposed method made use of DAD as a tool for peak identity and purity confirmation