Application of Response Surface Methodology in Development and Optimization of Stability Indicating RP-HPLC Method for Determination of Tolvaptan in Bulk and Formulation

Design of Experiment assisted stability indicating RP-HPLC was developed and optimized using response surface methodology for determination of Tolvaptan. Mobile phase was developed and optimized using Design of Experiment with response surface methodology. Acetonitrile and phosphate buffer with pH 5.5 (70:30% V/V) was optimized as mobile phase. The flow rate was maintained at 1ml/min. Stress studies were performed as per guidelines. Method was validated in accordance with regulatory requirements and results were within specified limits of regulatory guidelines. Tolvaptan was eluted at 3.24 min. It shows linearity from 2.5-15 µg/ml. Coefficient of correlation was 0.999, LOD and LOQ values were 1.0871 (µg/ml) and 3.2942 (µg/ml). Precision was determined with % RSD of 0.8669 and 0.9709%, mean percentage Recovery value was found to be 99.88 ±1.2. All stress degradation products are very well resolved from drug peak which indicate suitability indicating nature of the developed method. Design of Experiment technique can help in fast and economical optimization of mobile phase which inturn will save time for method development. The developed method is simple, accurate, sensitive which can be utilised as stability indicating method for identification of degradation products in routine analysis of the drug.