Electrochemical Oxidation of Chlorpromazine-Cyclodextrin Inclusion Complex

Abstract

The electrochemical oxidation of a chlorpromazine (CPZ)-cyclodextrin (CyD) inclusion complex was studied in phosphate buffers by means of cyclic voltammetry. The voltammogram of the CPZ-CyD system exhibits three oxidation waves. The first wave, which is due to the oxidation of CPZ to form its cation radical, is catalytic in nature, and its peak current depends on pH and on the buffer concentration. The second wave is attributed to the oxidation of CPZ cation radical-phosphate adduct. The third wave appears to be the result of further oxidation of CPZ sulfoxide-CyD complex. The formation of an inclusion complex of CPZ with CyD leads to a lowering of the peak current of the first wave and a shift in the peak potential to the positive side at the same time. The presence of CyD exerts no appreciable effect on the second wave, suggesting a minor interaction between the radical and CyD, and this is consistent with the absorption, circular dichroism, and 1H-nuclear magnetic resonance (NMR) spectra. Based on these results, an electrochemical reaction mechanism for CPZ-CyD system is proposed. © 1984, The Pharmaceutical Society of Japan. All rights reserved.