Development of a Reverse-Phase High-Performance Liquid Chromatography Method for Simultaneous Quantification of Tofacitinib Citrate and Berberine Chloride in Bulk, Injection and Plasma

The main aim of this study was to develop and validate a new reverse-phase high-performance liquid chromatography (RP-HPLC) method for the simultaneous estimation of tofacitinib citrate (TFC) and berberine chloride (BBC) in pharmaceutical injection formulations and blood plasma. An isocratic RP-HPLC method was used with a mobile phase consisting of phosphate buffer saline (pH 5.5) and acetonitrile at a ratio of 70:30, at flow rate of 1 mL/min at 25°C. Both drugs were detected at 306 nm. The proposed method demonstrated excellent linearity over a concentration range of 5-30 μg/mL for both the TFC and BBC, with correlation coefficients (R2) exceeding 0.999. System suitability parameters, including peak area, tailing factor, theoretical plates and resolution, were within acceptable limits, with relative standard deviations <2%. The recovery studies at 50, 100 and 150% showed mean recovery rates of 99.4-100.7% for TFC and 99.9-100.4% for BBC. The method exhibited high sensitivity, with low detection and quantification limits. The robustness was confirmed under slight variations in flow rate and mobile phase composition. The developed RP-HPLC method is accurate, reliable and suitable for simultaneous quantification of TFC and BBC in pharmaceutical and biological matrices, offering potential for routine quality control and pharmacokinetic studies.