Applications of simultaneous equation method and derivative method for the determination of rabeprazole sodium and levosulpiride in pharmaceutical dosage form and dissolution samples

Two simple, accurate, precise, economical procedures, entailing neither irksome sample treatment nor tedious extraction process have been developed for the simultaneous estimation of rabeprazole sodium and levosulpiride in combined tablet dosage form. The first method was based on employing simultaneous equation method for analysis of both drugs. Rabeprazole sodium and levosulpiride have shown absorbance maxima at 284 and 232 nm in methanol, respectively. The second method was based on derivative spectrophotometric method involving the determination of both the drugs at their respective zero crossing point (ZCP). The first order derivative spectrum was obtained in methanol and the determinations were made at 231.2 nm (ZCP of levosulpiride) for rabeprazole sodium and 246.2 nm (ZCP of rabeprazole sodium) for levosulpiride. The linearity was obeyed in the concentration range of 1-20 μg/ml for both drugs. The medium of dissolution was used 900 ml of phosphate buffer pH 7.4 using a USP type 2 apparatus at a stirring rate of 100 rpm. The drug release was evaluated by developed spectroscopic methods. The suitability of the developed method for quantitative determination of rabeprazole sodium and levosulpiride was proved by validation.