DEVELOPMENT AND VALIDATION OF A STABILITY-INDICATING RP-HPLC METHOD FOR SIMULTANEOUS ESTIMATION OF ACECLOFENAC AND TIZANIDINE HYDROCHLORIDE IN BULK DRUG AND PHARMACEUTICAL DOSAGE FORM

Kiran Sirvi*, Kamal S. Rathore

A simple, precise, accurate, rapid, and stability-indicating reverse-phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for the simultaneous estimation of Aceclofenac and Tizanidine Hydrochloride in bulk drug and pharmaceutical dosage forms. Aceclofenac is a widely prescribed non-steroidal anti-inflammatory drug (NSAID) used in the management of pain and inflammation, whereas Tizanidine Hydrochloride is a centrally acting α2-adrenergic agonist employed as a skeletal muscle relaxant for the treatment of muscle spasticity. The combination of these two drugs provides effective therapeutic management of musculoskeletal disorders, thereby necessitating a reliable analytical method for routine quality control and stability assessment. Chromatographic separation was achieved using a C18 reverse-phase column (250 mm × 4.6 mm, 5 µm particle size) with a mobile phase consisting of phosphate buffer (pH 3.5) and acetonitrile in the ratio of 45:55 (v/v). The mobile phase was pumped at a flow rate of 1.0 mL/min, and detection was carried out using a UV detector at 230 nm. The injection volume was maintained at 20 µL with a total run time of 10 minutes. Under the optimized chromatographic conditions, Aceclofenac and Tizanidine Hydrochloride exhibited well-resolved peaks with retention times of approximately 4.2 and 6.1 minutes, respectively. The developed analytical method was validated according to the International Council for Harmonisation (ICH Q2(R2)) guidelines with respect to specificity, system suitability, linearity, precision, accuracy, detection limit, quantitation limit, robustness, ruggedness, and assay. The calibration curves demonstrated excellent linearity over the selected concentration ranges with correlation coefficients greater than 0.999 for both analytes. Recovery studies showed excellent accuracy within 98–102%, while intra-day and inter-day precision studies produced percentage relative standard deviation (%RSD) values below 2%, indicating good repeatability and intermediate precision. The developed method demonstrated adequate sensitivity, robustness, and reproducibility, making it suitable for routine quality control analysis. The developed RP-HPLC method proved to be simple, economical, selective, and reliable for simultaneous estimation of Aceclofenac and Tizanidine Hydrochloride in bulk materials and pharmaceutical dosage forms. The method can be effectively applied in pharmaceutical industries for routine analysis, stability studies, formulation development, and regulatory quality control.