Simultaneous determination of pseudoephedrine sulfate, dexbrompheniramine maleate and loratadine in pharmaceutical preparations using derivative spectrophotometry and ratio spectra derivative spectrophotometry.

Two new spectrophotometric methods are described for the simultaneous analysis of pseudoephedrine sulfate-dexbrompheniramine maleate (DBP) and pseudoephedrine sulfate-loratadine combinations. In the first, derivative spectrophotometry, dA/dlambda values were read at zero-crossing points. In the second, ratio spectra derivative spectrophotometry, analytical signals were measured at the wavelengths corresponding to either maxima or minima for these drugs in the first derivative spectra of their ratio spectra. The procedures do not require any separation step. Mean recoveries were found to be >99% in the methods for these compounds in their synthetic mixtures. All the spectrophotometric methods proposed were compared with each other and HPLC which was also developed by us and applied to the pharmaceutical preparations selected.