Simultaneous determination of desloratadine and pseudoephedrine sulfate in tablets by high performance liquid chromatography and derivative spectrophotometry

Simple and accurate reversed phase liquid chromatographic and first derivative spectrophotometric methods have been developed for simultaneous determination of desloratadine and pseudoephedrine in combined dosage forms. The first method is based on the separation of both drugs by high performance liquid chromatography using a C18 column and 10 mm ortho-phosphoric acid: acetonitrile (77:23). The drugs are eluted at 1.0 ml/min flow rate and detected at 262 nm. Ondansetron was used as internal standard. The calibration graphs of desloratadine and pseudoephedrine were linear in the range of 1.0–10.0 μg/ml and 48–480 μg/ml, respectively. The detection limits of the method were found to be 0.14 μg/ml and 3.80 μg/ml for desloratadine and pseudoephedrine, respectively. The derivative spectrophotometric method depends on measuring the first derivative amplitudes at 280 and 244 nm for desloratadine and pseudoephedrine, respectively. The calibration graphs were linear in the range of 2.5–15.0 μg/ml for desloratadine and 120–720 μg/ml for pseudoephedrine. The detection limits were found at 0.38 μg/ml and 21.45 μg/ml for desloratadine and pseudoephedrine, respectively. The proposed methods were successfully applied to the determination of these drugs in commercially available tablets