Simultaneous determination of cefixime trihydrate and dicloxacillin sodium in pharmaceutical dosage form by reversed-phase high-performance liquid chromatography.

A simple, precise, accurate, and sensitive RP-HPLC method for simultaneous determination of cefixime trihydrate and dicloxacillin sodium in combined tablet dosage form was developed and validated. Chromatographic separation of the two drugs was performed on a Purospher BDS C18 column (25 cm x 4.6 mm id, 5 microm particle size). The mobile phase methanol-0.01 M phosphate buffer (75 + 25, v/v), adjusted to pH 3 with glacial acetic acid, was delivered at a flow rate of 1.0 mL/min. Detection was performed at 227 nm. Separation was completed within 10 min. Calibration curves were linear with R2 between 0.99 to 1.0 over a concentration range of 2-10 microg/mL for cefixime trihydrate and 5-25 micromL for dicloxacillin sodium. The RSD for intraday and interday precision was < 2.0%.