RP-HPLC METHOD DEVELOPMENT AND VALIDATION FOR SIMULTANEOUS DETERMINATION OF ESOMEPRAZOLE AND DICLOFENAC SODIUM IN PHARMACEUTICAL DOSAGE FORMS

A new RP-HPLC method was developed and validated for simultaneous determination of esomeprazole (ESO) and diclofenac sodium (DIC) in pharmaceutical dosage forms. BDS Hypersil C18 column (250 x 4.6 mm, 5 mu m) and mobile phase consisting of methanol and 50 mM phosphate buffer (35: 65) were used in this analysis. The flow rate was adjusted at 1.0 mL/min and detection was performed at 213 nm wavelength for both esomeprazole and diclofenac sodium. Etoposide (ETO) was used as internal standard giving a retention time of 4.13 min. The method was linear in a range of 25-1000 ng/mL and 15.5 - 500 ng/mL for ESO and DIC, respectively. The method has good linearity (r(2) = 0.999) with the intra-day and inter-day variability less than 3% for both drugs. The limits of detection were 15 and 10.5 ng/mL, while the limits of quantification were 25 and 15.5 ng/mL for ESO and DIC, respectively. The proposed method demonstrates good robustness, resisting to small deliberate changes in pH and flow rate of mobile phase. The developed method was successfully applied for determining drug concentrations in spiked human plasma, injection, capsule and tablet dosage forms, where it exhibited good performance and reproducibility.