Electrochemical Studies of the Neuraminidase Inhibitor Zanamivir and its Voltammetric Determination in Spiked Urine

Zanamivir is a member of a new class of antiviral agents that selectively inhibit the enzyme neuraminidase of influenza A H5N1 and H1N1 viruses. Although zanamivir is the compound of biological interest, so far it has not been a subject of any electrochemical studies. It was stated, that zanamivir can act as an electrocatalyst at HMDE. The electrode mechanism is connected with the hydrogen evolution reaction catalyzed by zanamivir as the guanidine compound. A new adsorptive catalytic method for its voltammetric (SW AdSV) determination was developed. The dependence of the peak current on pH, buffer concentration, nature of the buffer and instrumental parameters were studied. The best results were received in citrate-phosphate buffer at pH 2.2. This electroanalytical procedure enabled to determine zanamivir in the concentration range 4.8 x 10(-7)-1.2 x 10(-5) mol L-1 in supporting electrolyte and diluted urine. Precision, repeatability and accuracy of the method were checked in both media. The detection and quantification limits were found to be 1.5 x 10(-7) and 4.8 x 10(-7) mol L-1 respectively. A standard addition method was used to determine zanamivir in spiked urine.