ABSTRACT

The present paper describes a sensitive and simple RP-HPLC-PDA method for the simultaneous estimation of Naproxen Sodium (NPX) and Diphenhydramine Hydrochloride (DPH) in the presence of their degradants. The drugs were subjected to stress conditions (forced degradation) to show the stability-indicating power of the method. The separation was achieved on Inertsil ODS C18 column (250×4.6mm, 5μ). The optimized liquid chromatographic conditions were found to be a mobile phase of 15mM ammonium acetate buffer: acetonitrile (60:40V/V) combination at a flow rate of 1.0 mL/min in isocratic mode with an injection volume of 10µL. The proposed method provided retention times of 4.6 and 10.8min, with linear responses over a range of 60-140μg/mL and 10-30μg/mL and regression coefficient (R2) of 0.999 and 0.996 respectively for NPX and DPH. No interference from other components of pharmaceutical dosage form and degradants was observed. The method was validated as per ICH guidelines and was successfully applied for the simultaneous estimation of both the drugs in bulk and tablet preparations.