Objective: Simple and sensitive an extractive-spectrophotometric method have been developed for the determination of four important antihistaminic drugs, namely desloratadine (DSL), chlorpheniramine maleate (CPM), diphenhydramine hydrochloride (DPH) and fexofenadine (FXO).Methods: This method is based on the formation of colored ion-pair complexes between the basic nitrogen of the drugs and halofluorescein dyes, namely rose bengal (RB) dye in weak acidic medium. The formed complexes were extracted with dichloromethane measured spectrophotometrically at 550 nm.Results: The reaction conditions were optimized to obtain the maximum color intensity. Beer's law was obeyed with a good correlation coefficient (0.9963-0.9975) in the concentration ranges 1-6, 4-18, 6-16 and 2-22 µg/ml for DSL, CPM, DPH and FXO, respectively. The composition ratio of the ion-pair complexes was found to be 1:1 as established by Job's method.Conclusion: The proposed method was successfully extended to pharmaceutical preparations. Excipients used as additive in commercial formulations did not interfere in the analysis. The proposed method can be recommended for quality control and routine analysis where time, cost effectiveness and high specificity of analytical technique are of great importance.Â
