Spectrophotometric and Kinetic Determination of Some Sulphur Containing Drugs in Bulk and Drug Formulations

A. M. El-Brashy, M. S. Metwally, and A. A. AbdelalAnalytical Chemistry Department, Faculty of Phar macy, Mansoura University, Mansoura 35516, EgyptReceived August 2, 2003Two simple and sensitive spectrophotometric methods were developed for the determination of carbocisteine,penicillamine, ethionamide and thioctic acid in bulk and in their pharmaceutical preparations using alkalinepotassium permanganate as an oxidizing agent. The first one involves determination of ethionamide andthioctic acid by spectrophotometric investigation of th e oxidation reaction of the two drugs. The second methodinvolves determination of carbocisteine and penicillamine by kinetic studies of the oxidation reaction of thesetwo drugs at room temperature for a fixed time of 20 minutes. The absorbance of the colored manganate ionswas measured at 610 nm in both methods. 1-10 µg/mL of ethionamide and thioctic acid could be determinedby the spectrophotometric method with detection limits of 0.11 and 0.089 µg/mL for the two drugs respectively.2-10 µg/mL of carbocisteine and penicillamine could be de termined by the kinetic method with detection limitsof 0.14 and 0.21 µg/mL respectively. The two methods were successfully applied for the determination of thesedrugs in their dosage forms.Key Words : Kinetic determination, Carbocisteine, Potassium permanganate, Pharmaceutical analysis, Spec-trophotometryIntroductionThe importance of these sulphur compounds is due to theirwide spread and different pharmacological effects. Carboci-steine (I) is a mucolytic drug used for treatment of disordersof the respiratory tract associated with excessive mucus,ethionamide (II) is an antibacterial drug (tuberculostaticagent), Penicillamine (III) is used for treatment of rheumatoidarthritis and in treatment of lead poisoning as a chellatingagent, it also used for elimination of copper in treatment ofhepatolenticular degeneration (Wilson's disease) and thiocticacid (IV) is used for treatment of liver dysfunction anddiabetic neuropathy and antidote to poisonous mushrooms[Amantia species].