Dielectric Spectroscopy Studies on Some Pharmaceutical Substances

Abstract

Abstract In this work, measurements of a.c. complex impedance were made on Artesuminin (a drug used to treat multi- drug resistant strains of Falciparum malaria). The compound (a sesquiterpene lactone ) is isolated from the shrub Arlemisisa Annua used in traditional Chinese medicine) . The aim of studying the impedance of Artesumine tablets was to predict the solubility dependence on the dielectric constant from the knowledge of the dynamic relaxation behaviors at different acidities. The physical properties that are sensitive to the microstructure were only the bulk (grain) effects which was an important factor in understanding the over all properties of the material. The frequency of the dielectric spectroscopy was in the range 100 — 106 Hz Analysis of the data was based on the possibility of representing the complex impedance by an equivalent circuit that allowed separating and measuring the conductance and capacitance components of the polarization process. Furthermore, the method also enabled the dielectric properties of the material to be evaluated (conductivity, capacitance, relaxation time and then dielectric constants). Owing to the measured dielectric constants of the two drugs in the simulated gastric fluid (acidic pH), it might be expected that absorption of Fansidar could possibly start in the stomach whereas the reduced solubility of Artisunate would limit its gastric absorption. ' -