Spectrophotometric method for indirect determination of antihypertensive drugs in pharmaceuticals

Abstract

A spectrophotometric method is proposed for the determination of antihypertensive drugs namely Propranolol and Methyldopa in their pure forms and in pharmaceutical formulations, based on the oxidation of the drugs with an excess of N-Bromo succinimide and the residual oxidizing agent bleaches the red colored eriochrom black-T (EBT) which is measured at 530 nm at room temperature. Linear calibration graphs were obtained in the concentration range 0.1-10 and 0.1-9 μg ml-1 with molar absorptivity 6.06×104 and 4.60×104 L.mol-1.cm-1 for above drugs respectively. No interference was observed coexistent substance. The proposed method was applied successfully for the determination of the drugs in their pharmaceutical formulations.