الفهرس 
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Abstract
New two simple, reproducible and accurate spectrophotometric methods have been developed for the determination of some antihistamine drugs; azelastine HCl (AZL), loratidine (LOR), desloratidine (DES), acrivastine (ACV) and ebastine (EBS) in pure forms and pharmaceutical formulations. The first method is based on the formation of yellow colored chloroform ion-pair complex between the basic nitrogen of the drugs (AZL, LOR, DES, ACV and EBS) and acid dyes, namely; bromocresol green (BCG), methyl orange (MO) and alizarin red S (ARS) in acidic buffer of pH range (2.5-5.0). Beer’s law was obeyed in the range 0.5–20, 1.0-20 and 2.0-24 µg mL−1 using BCG, MO and ARS, respectively. The correlation coefficient was ≥0.9993 with a relative standard deviation (R.S.D.) of ≤ 1.28. The second method is based on the formation of charge-transfer complex of the studied drugs DES, LOR, ACV and EBS with π-acceptors (DDQ, p-CLA or TCNQ) in acetonitrile. Beer’s law is obeyed in the concentration ranges 5.0-120, 10-200 and 2.0-28 g mL-1 using DDQ, p-CLA and TCNQ, respectively. The correlation coefficient was ≥ 0.9992 with a relative standard deviation (R.S.D.) of ≤ 1.24. The limits of detection and quantification are also reported. Intra-day and inter-day precision and accuracy of the methods have been evaluated. The proposed methods were successfully applied to determine the studied drugs in their formulations without any evidence for interference from pharmaceutical additives and the results were statistically compared with those of the reference methods by applying Student’s t-test and F-test. The accuracy of the methods was further ascertained by performing recovery studies via standard-addition method. The proposed methods can be confidently applied for quality control and routine analysis of the studied drugs.