engleski

Square-Wave Voltammetric Determination of Simvastatin

The electrochemical properties of the lipid-lowering compound simvastatin were investigated on graphite and mercury electrode. Simvastatin belongs to a class of drugs called statins, which act by inhibition of 3-hydroxy-3-methylglutaryl-coenzyme A reductase. Also, simvastatin inhibits oxidation of native and modified low-density and high-density lipoproteins. The electrochemical reduction and adsorptive voltammetric behaviour of simvastatin were studied by means of cyclic and square-wave voltammetry in different supporting electrolytes of various pH values. It was found that the reduction of simvastatin proceeds via a relatively stable intermediate, which is transformed into an aldehyde by a coupled chemical reaction or can be reoxidized back to simvastatin. The electrode mechanism exhibits properties of a surface redox reaction. The peak current of the first of two peaks developed for this drug in 0.1 M Na_2B_4O_7-KH_2PO_4 buffer at pH 7 has been considered for the analytical study. The square-wave frequency and amplitude were changed between 50 and 900 Hz, and from 10 to 120 mV, respectively. The sensitivity of the technique depends primarily on the kinetics of the redox reaction. A sensitive analytical method for the trace analysis of simvastatin based on the adsorptive stripping technique has been developed. The calibration plot was linear in the range 5 × 10^-8 - 7.5 × 10^-7 M. Application of the square-wave voltammetric method to the simvastatin determination in a pharmaceutical formulations, without sample pre-treatment, resulted in acceptable deviation from the stated concentration Solid microparticles of the drug were mechanically immobilized on the surface of the paraffin impregnated graphite electrode and investigated by square-wave voltammetry in order to develop a method for a quick detection of simvastatin. The microparticles were oxidized at 1.1 V in totally irreversible electrode reaction. Using the abrasive stripping voltammetry, a qualitative analysis of powders of pharmaceutical dosage forms could be performed.

simvastatin; square-wave voltammetry; abrasive stripping voltammetry

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