Developed and Validated Spectrophotometric Methods for the Evaluation of Artesunate and Dihydroartemisinin in Tablets Using Potassium Permanganate

Abstract

The widespread importation and distribution of counterfeit antimalarials especially artemisinin derivatives into Sub Saharan Africa is becoming a serious problem as this may lead to the appearance of highly virulent multidrug resistant plasmodium species. Based on this, a simple, sensitive and reproducible method is developed for the determination of Artesunate (ART) and Dihydroartemisinin (DHA) in tablets as highly technical analytical equipment are lacking in this region. The method is based on redox reactions of ART and DHA with potassium permanganate in alkaline medium and the determination of the bluish-green coloured specie spectrophotometrically at 600 nm . The increase in absorbance in both cases were proportional to drug concentration obeying Beer’s law in the range of 0.5 to 30 and 1.0 to 40 ?g/ml with correlation coefficients of 0.9989 and 0.9995 respectively. The molar absorptivity were 2.10 x 104 and 3.02 x 104 l/mol/cm for ART and DHA respectively, Sandell sensitivity were 0.018 and 0.0127?g/cm2 .The limit of detection and quantification were 0.51 and 1.2 ?g/ml for ART and 0.48 and 1;18 for DHA . The intraday and inter day precision evaluated as Relative standard deviation (RSD %) and accuracy evaluated as Relative error (RE%) were ? 3% in all cases. The method was statistically compared with an official method via t-test and F-test and thereafter used to assay artesunate and dihydroartemisinin tablets procured locally within Uyo Metropolis. The practicability of the method was confirmed by performing recovery study via standard addition method with excellent recoveries ranging between ?99% and ?104 in all cases showing no interference from excipients commonly used during tablets formulation.