Simultaneous determination of loratadine and desloratadine in pharmaceutical preparations using liquid chromatography with a microemulsion as eluent.

A rapid HPLC procedure for analytical quality control of pharmaceutical preparations containing the antihistaminic drug substance loratadine and/or its analog desloratadine (which is also an active metabolite of loratadine) was developed using a microemulsion as the eluent. The separation was performed on a column packed with cyanopropyl bonded stationary phase adopting UV detection at 247 nm using a flow rate of 1 ml/min. The optimized microemulsion mobile phase consisted of 0.1M sodium dodecyl sulphate, 1% octanol, 10% n-propanol and 0.3% triethylamine in 0.02 M phosphoric acid, pH 3.0. The developed method was validated in terms of specificity, linearity, lower limit of quantification, lower limit of detection, precision and accuracy. With the proposed method satisfactory resolution between loratadine and desloratadine (resolution factor=3.85). The method requires a minimum of sample handling and is rapid (10 min), and reproducible (R.S.D.<2.0%). The mean recoveries of the analytes in pharmaceutical preparations were in agreement with those obtained from a reference method, as revealed by statistical analysis of the obtained results using the Student's t-test and the variance ratio F-test. Pseudoephedrine, the co-formulated drug substance, did not interference with the assay and was successfully separated using the developed HPLC method.