Experimental Design Approach for Selective Separation of Vilazodone HCl and Its Degradants by LC-PDA and Characterization of Major Degradants by LC/QTOF–MS/MS

Abstract

A selective, rapid, accurate and precise stability-indicating RP-HPLC method was developed for monitoring vilazodone in the presence of its degradation products (DPs) in API and pharmaceutical dosages. Chromatographic separation was achieved using a Grace phenyl C₁₈ column (250 × 4.6 mm, 5 µm particle size) at a flow rate of 1.0 mL min⁻¹ with a linear gradient elution of ammonium acetate buffer (10 mM, pH 5.0 adjusted by acetic acid) with acetonitrile as the mobile phase. Detection was performed at 240 nm. The chromatographic conditions were optimized by the design of experiments to obtain the best possible separation with a minimum number of trials. A face-centered central composite design (three levels for each factor) was employed for optimization, and an interaction of the independent variables (pH of mobile phase, column temperature and  % of organic modifier) on the resolution of critical pairs was studied. The drug was subjected to the stress conditions of hydrolytic (acid, base and neutral), oxidative, thermal and photolytic degradation. It was found to be degraded significantly in hydrolytic (basic and acid) and oxidative conditions, while it was stable in neutral hydrolytic, thermal and photolytic conditions. LC-QTOF/MS/MS studies were carried out to characterize the major DPs. The method was fully validated for selectivity, linearity, accuracy, precision and robustness in compliance with ICH guideline Q2 (R1).