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Metoprolol tartrate is a selective b-adrenergic antagonist, which is used in the treatment of cardiovascular disorders such as hypertension, angina pectoris, cardiac arrhythmias and myocardial infarction. The drug is quite sensitive, even a small dose of the drug gives sufficient blockade. Since the bblockers are also misused as doping agents in sports and therefore these drugs have been added to the list of forbidden drugs by the International Olympic Committee (IOC). 1)Therefore the development of an analytical method for the determination of metoprolol tartrate is of great significance.The assay of the drug is listed in the monograph of British Pharmacopoeia, which describes a potentiometric titration method.2) Several analytical methods have been developed for the determination of metoprolol in biological fluids and pharmaceutical formulations based on high performance liquid chromatography, [3][4][5][6][7][8][9][10][11] gas chromatography, 12,13) capillary electrophoresis, 14) thin layer chromatography, 15,16) infrared spectroscopy, 17) and electrochemical methods. 18,19) The above mentioned techniques are sensitive but expensive and require laborious clean up procedure prior to analysis. Spectrophotometry is the technique of choice even today due to its inherent simplicity and therefore frequently used in the laboratories of the developing countries to overcome versatile analytical problem. The drug has been determined in the visible region based on ion-pair formation between drug and reagents like oxidized quercetin 20) ; bromophenol blue, bromocresol purple, bromocresol green ; and carbon disulfide-copper chloride. 24)The charge transfer complexation reactions of metoprolol tartrate with s and p-acceptors 24,25) have also been utilized for its quantification in pharmaceutical formulations. Shingbal and Bhangle 26) have reported a spectrophotometric method based on the reaction of drug with 2,4-dinitrofluorobenzene in HCl/dioxan medium to form a colored chromophore, which absorbs maximally at 380 nm. The quantification of metoprolol tartrate was done on treatment of the drug with ammonium metavanadate, 27) FeCl 3 , 28) N-bromosuccinimide, 29) and a mixture of KNO 3 and H 2 SO 4 followed by addition of alkali to get colored chromophore.30) The literature is still poor in analytical procedures based on kinetic spectrophotometry for the determination of drug in pharmaceutical preparations. There is, therefore, a need for a simple and sensitive kinetic spectrophotometric method for the determination of metoprolol tartrate in pharmaceutical formulations. It was found that potassium permanganate oxidizes the metoprolol in alkaline medium and this reaction has not been used before to quantify the drug spectrophotometrically. This paper describes a simple and sensitive kinetic spectrophotometric method for the determination of metoprolol tartrate in drug formulations. The method involves the oxidation of drug with alkaline potassium permanganate at 25Ϯ1°C and subsequent measurement of absorbance at 610 nm. The in...