Abstract: A simple and reliable reversed-phase high performance liquid chromatographic method (HPLC) for the routine analysis of pseudoephedrine hydrochloride and dextromethorphan hydrobromide in composite pseudoephedrine hydrochloride dry suspension has been established. HPLC determination for the drug was performed in a Lichrospher C6H6 column and detected at 220 nm. Acetonitrile-H2O-H3PO4 (50∶50∶0.1, v/v, pH 2.5, containing 1 g/L sodium dodecyl sulfate) was used as the mobile phase and the flow rate was 1.2 mL/min. The method was proved to be linear in the ranges of 1.03-206 mg/L and 5-200 mg/L for dextromethorphan hydrobromide and pseudoephedrine hydrochloride, respectively. The relative standard deviations of intra-assay (n=7) and inter-assay (n=5) were 1.0% and 1.5% for pseudoephedrine hydrochloride analysis and 1.8% and 2.2% for dextromethorphan hydrobromide analysis. The recoveries of pseudoephedrine hydrochloride and dextromethorphan hydrobromide were 95.7%-98.7% and 100.0%-101.8%, respectively. The method has been successfully applied to the simultaneous determination of pseudoephedrine hydrochloride and dextromethorphan hydrobromide in composite pseudoephedrine hydrochloride dry suspension.

Key words: composite pseudoephedrine hydrochloride dry suspension, dextromethorphan hydrobromide, drug , pseudoephedrine hydrochloride, reversed-phase high performance liquid chromatography