Eco‐Conscious RP‐HPLC Method for Concurrent Quantification of Assay and Dissolution Testing of Methocarbamol and Diclofenac Potassium in Tablet Formulations

A common combination of methocarbamol (MTH) and diclofenac potassium (DCL K) relieves musculoskeletal pain and inflammation through centrally acting muscle relaxants. A dual‐function RP‐HPLC method was used to analyze the assay and dissolution testing of MTH and DCL K simultaneously. As part of the suggested method, green and white analytical chemistry standards were incorporated to ensure sustainability and compatibility. We performed a chromatographic separation on a C8 column (15 cm × 4.6 mm, 5 μm) with a mobile phase of phosphate buffer and ethanol (30:70 v / v ), adjusted to pH 2.5 ± 0.1, yielding sharp and well‐resolved peaks with retention times of 2.183 min for MTH and 6.652 min for DCL. A 275‐nm dual UV detector was used to detect the separation at a flow rate of 1.0 mL/min. Sensitivity parameters demonstrated low detection capabilities, with limits of detection (LOD) of 0.069 μg/mL for MTH and 0.012 μg/mL for DCL, and limits of quantification (LOQ) of 0.210 μg/mL and 0.035 μg/mL. Over an extended sample period of 30 min with 100 revolutions per minute (rpm), USP Apparatus II (Paddle) was used to measure dissolution at a temperature of 37.0 ± 0.5°C in phosphate buffer (pH 6.8). With both active pharmaceutical ingredients, 75% of the drug was released within 30 min. A combination of suitability (RSD 2%) and precision (raw data 2%) makes the method an excellent choice for routine quality control. In keeping with the changing environment and regulatory requirements, pharmaceutical analysis can become more efficient and sustainable. Accelerated stability studies were conducted on the finished dosage form under ICH‐recommended conditions for 6 months. Sustainability was assessed using the Analytical Eco‐Scale, Environmental and Practical Performance Index (EPPI), and Click Analytical Chemistry Index (CACI). The method achieved an Eco‐Scale score of 91, classifying it as an excellent green method, an EPPI score of 97.9, and a CACI score of 80, confirming its efficiency and practicality for routine quality control.