Modified electrodes in the study of selected pharmaceutical drugs

Abstract

This research was focused <;mthe analysis of selected human drugs and herbal medicines using using surface modified /derivatized electrodes, where the working electrode surface was modified using the chemical substrate of interest. Inthe study, the following drugs with antimalarial properties were analyzed: quinine, Sulfadoxine+ Pyrimethamine, 2-sulfanilamido-3-methoxypyrazine+Pyrimethamine, halofantrine hydrochloride, and lumefantrine+artemether, which are the most commonly used in the management of malaria in Africa. Other drugs were amoxil (an antibiotic) and paracetamol (an analgesic). Analysis on cinchona tree extract and an herbal antimalarial, malbet was also done. The electrochemical technique used is cyclic voltammetry. The potential of the electrode was varied with the potential window ranging from -O.4Vto a selected upper limit. The scan rate was variable but mostly 20mV/sec. The mechanistic pathways of the oxidation/reduction of the different drugs studied have been proposed and analysis on the effect of pH on the oxidation potential conducted. In an attempt to see whether the nature of the host matrix will improve the redox activity of the drugs studied, experiments were conducted on carbon electrode surface with different host matrices e.g bentonite, polyaniline, polythiophene, and the drug itself. Interaction of the pharmaceutical preparations with other substances was considered. This included acetylsalicylic acid and nicotinic femiplan, folic acid, vitamin C, milk, tea, glycerine, hydrocortisone, paracetamol, methionine, arginine, tyrosine and leucine. Therole of metal ion catalysis on the redox process has also been investigated. The metal ions studied included Co2+,Zn2+,Cu2+,and Snz+adsorbed on the bentonite modified carbon graphite working electrode. The results obtained show that surface modified electrode technique can be used as a diagnostic tool in the analysis of pharmaceutical preparations and herbal medicines.