A Validated Spectrophotometric Approach for the Concurrent Estimation of Paracetamol and Methocarbamol in Combined Tablet Formulations with Practicality and Greenness Assessment

ABSTRACT A simple, rapid, and cost-effective UV spectrophotometric method based on the simultaneous equation (Vierordt’s) approach was developed and validated for the simultaneous estimation of paracetamol (PTM) and methocarbamol (MCM) in combined tablet dosage forms. The method utilizes absorbance measurements at 250 nm and 225 nm for PTM and MCM, respectively, eliminating the need for prior separation. The method was validated in accordance with ICH guidelines for specificity, linearity, accuracy, precision, limit of detection (LOD), and limit of quantification (LOQ). Specificity studies confirmed the absence of interference from excipients at the selected wavelengths. The method exhibited good linearity over the concentration ranges of 4–24 µg/mL for PTM and 16–32 µg/mL for MCM. Accuracy was assessed by recovery studies, yielding values in the range of 99.49–109.24% for PTM and 94.59–113.79% for MCM. Precision studies demonstrated good repeatability and reproducibility, with %RSD values less than 2% for both intraday and interday analyses. The LOD and LOQ values indicated adequate sensitivity of the method. The method was successfully applied to the analysis of a marketed formulation, with assay results of 95% for PTM and 98.2% for MCM. Ruggedness and robustness studies confirmed the reliability of the method under small variations in analytical conditions. Furthermore, greenness evaluation using GAPI, AGREE, and BAGI tools demonstrated that the method is environmentally sustainable, simple, and suitable for routine quality control applications. This study reports a novel simultaneous equation-based UV method for this drug combination, providing an efficient alternative to more complex analytical techniques.