METHOD DEVELOPMENT AND VALIDATION FOR THE SIMULTANEOUS ESTIMATION OF LEVOTHYROXINE AND LIOTHYRONINE IN BULK AND PHARMACEUTICAL DOSAGE FORMS BY RP-HPLC

A swift, precise, and dependable Reverse Phase High-Performance Liquid Chromatography (RP-HPLC) technique has been established and validated for the concurrent quantification of Levothyroxine and Liothyronine in both bulk substances and pharmaceutical formulations. The chromatographic separation utilized a C18 column, with a mobile phase consisting of phosphate buffer (pH 3.5) and acetonitrile, at a flow rate of 1.0 mL/min. Detection occurred at a wavelength of 225 nm. The retention times for Levothyroxine and Liothyronine were sufficiently distinct, ensuring optimal resolution. Validation of the method was conducted in accordance with ICH guidelines, assessing parameters such as accuracy, precision, linearity, specificity, robustness, limit of detection (LOD), and limit of quantification (LOQ). Calibration curves demonstrated excellent linearity, with correlation coefficients exceeding 0.999. Recovery studies validated the method's accuracy, yielding results between 98% and 102%. The method has been effectively utilized for commercial formulations, confirming its appropriateness for routine quality control of Levothyroxine and Liothyronine in pharmaceutical products.