Different Spectrophotometric Methods of Operating Ratio Spectra for Analyzing Pharmaceutical Combinations of Loratadine and Dexamethasone

Document Type : Original Article


1 Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, Tanta University, Tanta 31111, Egypt

2 Bioequivalence Unit, Pharmaceutical Services Center, Faculty of Pharmacy, Tanta University, Tanta 31111, Egypt


Two different ratio spectrophotometric methods are introduced for the concurrent dedication of a binary combination of Dexamethasone (DEX) and Loratadine (LOR) in laboratory prepared combinations and pharmaceutical dosage form directly. Both methods are simple and do not need advanced methods or instruments. They are also sensitive and selective and may be utilized for routine analysis of DEX and LOR in their available dosage form without earlier separation. The methods are suitable and valid also for application in research facilities that don’t have liquid chromatographic instruments. Method (I) is ratio derivative spectrophotometry (RDM), Method (II) is ratio subtraction (RSM) coupled with extended ratio subtraction method (EXRSM). The mathematical clarification for both methods is explained. Calibration curves of the two methods are linear in the concentration ranges between 3.0-25.0 μg /ml and 7.5-40.0 μg /ml for DEX and LOR in 0.1N MethanolicHCl, respectively. Both methods are validated as stated by the ICH guidelines where accuracy, precision, and repeatability are found to be within acceptable limits.


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