Ultraviolet, Visible and Infrared Simultaneous Spectrophotometric Assay of Pyrimethamine and Sulphadoxine in Dicomponent Antimalarial Drugs

Abstract

The development of new methods for the assay of active components in dicomponent antimalarial drugs are of great interest to pharmaceutical analysis ,specially in developing countries. Pyrimethamine and sulphadoxine, in particular, are still of continued use in the chemo- therapy treatment of malaria disease. The growing need to develop more simple ,accurate and sensitive assay methods is obvious. In the present work pyrimethamine and sulphadoxine were spectrophotometrically determined not only in the visible but also in the ultraviolet and infrared regions of the electromagenatic spectrum ,using the two simultaneous equations method . Whereas the ultraviolet method was based on measurement of the maximum absorbance of pyrimethamine and sulphadoxine at 275 nm and 265 nm, the visible procedure was developed on the bases of their maximum absorbance of their cholaranilic complexes at 520 nm, 500 nm respectively. The Infrared method, however, was based on their characteristic absorbance,(i,e. –log10 transmittance) at 833 nm,1319 nm respectively. In all the three developed simultaneous spectrophotometric assay methods of pyrimethamine and sulphadoxine, contents in fansidar show a good agreement with those given in the recipe formulation of fansidar drug brand.