A VALIDATED STABILITY-INDICATING RP-HPLC METHOD FOR PARACETAMOL AND LORNOXICAM: APPLICATION TO PHARMACEUTICAL DOSAGE FORMS

A new method for the simultaneous determination of paracetamol (PR) and lomoxicam (LR) has been developed by reversed phase HPLC from the combination drug product. The separation achieved on a C-18 column using acetonitrite and 0.02 M potassium dihydrogen phosphate in the ratio of 35.65 (v/v) as the mobile phase at a flow rate of 1.0 mL/min. Both the components were monitored at a single wavelength at 260 nm and the column temperature was maintained at 30 C throughout the analysis. A linear response was found in the concentration range of 125-375 pg/mL for PR and 2-6 pg/mL for LR, with the correlation coefficient of more than 0.999. Although the tablet contained a high dose of PR (500 mg) and a low dose of LR (8 mg), a single HPLC method was developed and the infra- as well as inter-day precision was obtained at less than 2% of RSD. The accuracy results obtained were between 98% and 102%. The drug was intentionally degraded under acidic, bask, peroxide, thermal and photolytic conditions. The major degradation observed for both PR and LR under peroxide condition indicated that the drug product is susceptible to oxidation. The degraded peaks were properly resolved from PR and LR. Hence, the method is stability indicating