EXTRACTION-SPECTROPHOTOMETRIC DETERMINATION OF SOME ANTIHYPERTENSIVE DRUGS IN PHARMACEUTICAL AND BIOLOGICAL FLUIDS USING TWO SULPHONPHTHALEIN DYES

Objective: Two simple and sensitive extractive spectrophotometric methods have been described for the determination of some antihypertensive drugs namely, bisoprolol (BIS), carvedilol (CAR), propranolol (PRP) and telmisartan (TLM) either in pharmaceutical formulations or biological fluids. Methods: The proposed methods involve the formation of yellow colored ion-pair complexes of the studied drugs with two sulphonphthalein dyes as bromophenol blue (BPB) and bromocresol purple (BCP) in acidic medium. Results: The colored products are extracted into methylene chloride and measured spectrophotometrically at 402 nm for all the drugs. Beer's law limits, Sandell sensitivity values, limits of detection (LOD) and quantification (LOQ) values have also been reported for both the methods. The composition of the ion-pair complexes was found 1: 1 by Jobʼs continuous variations method. The effects of concentration of dye, pH and interference of excipients have been studied and optimized. The accuracy and precision of the methods were evaluated on intra-day and inter-day basis; the relative standard deviation (RSD) was<1.72%. Various analytical parameters have been evaluated and the results have been validated by statistical data and indicated no significant difference in accuracy and precision. Conclusion: The proposed methods were successfully applied to the determination of the studied drugs in pharmaceutical formulations and in biological fluids. Keywords: Antihypertensive drugs, Sulphonphthalein dyes, Ion-pair, Pharmaceuticals