Determination of some histamine H1-receptor antagonists in dosage forms.

Three simple and accurate methods are presented for determination of Cetirizine, Fexofenadine, Loratadine and Acrivastine in pure form and commercial dosage forms. The first method is based on the reaction of the above cited drugs with bromocresol purple dye to form ion-pair complex extractable with chloroform and subsequently measured spectrophotometrically. Secondly, eosin gives with these drugs ion-pair complex, measurable directly without extraction both spectrophotometrically and spectrofluorimetrically. The last method involves the base-catalysed condensation of mixed anhydrides of organic acids (citric acid/acetic anhydride) where as the tertiary amino group in the above-cited drugs acts as the basic catalyst. The product of condensation is measured spectrophotometrically. All the reaction conditions for the proposed methods have been studied.