Kinetic spectrophotometric determination of beta-adrenergic antagonists using alkaline potassium permanganate

A new simple and sensitive kinetic spectrophotometric method is described for analysis of bisoprololfumarate (BSF) and propranolol hydrochloride (PRH) in pure and pharmaceutical formulations. The method involves the reaction of the drugs with alkaline potassium permanganate producing bluish-green manganate species. The reaction was followed spectrophotometrically by measuring the increase in the absorbance from the formation of MnO42- at 610 nm. The different experimental parameters affecting the development and stability of the colors were carefully studied and optimized. The fixed-time method is adopted for constructing the calibration curves, which were found to be linear over the concentration ranges of 2.0-16 mu g/mL for BSF and 2.0-18 mu g/mL for PRH. The determination of the studied drugs by initial rate, variable time and rate-constant methods was feasible with the calibration equations obtained but the fixed time method has been found to be more applicable. The method has been successfully applied for the determination of drugs in commercial dosage forms. The results were validated through inter-day and intra-day precision assays according to the ICH guidelines and also through recovery studies. Statistical comparison of the proposed method with that of official methods shows excellent agreement and indicates no significant difference in their accuracy and precision.