Spectrophotometric Determination Of Some Phenothiazine Drugs With Iodic Acid
A sensitive and accurate spectrophotometric method for the quantitative determination of four phenothiazine drugs in either pure form or in pharmaceutical formulation is proposed. The method is based on the development of a red or bluish-green coloured product with iodic acid in phosphoric acid medium. The reaction proceeds via oxidation of the phenothiazine nucleus into a semiquinonoid radical. The optimum reaction conditions and other analytical parameters are evaluated. The influence of substrates commonly employed as excipients with phenothiazine drugs has been studied. Results of analysis of pure drugs and their dosage forms by the proposed method are in good agreement with those of the official method.