Electrochemical Determination of Lacidipine

Lacidipine is an antihypertensive drug that is oxidizable at the glassy carbon electrode. The voltammetric oxidation of lacidipine in aqueous-alcoholic solutions (70 + 30) produces a well-defined voltammetric peak when subjected to a differential pulse voltammetric experiment. This peak is due to oxidation of the dihydropyridine ring to a pyridine derivative. This voltammetric response result is irreversible, pH dependent, and diffusion controlled. The best resolution for the peak was obtained at pH 6 in Britton-Robinson buffer-ethanol (70 + 30). The peak potential at pH 6 was 800 mV against an Ag-AgCI reference electrode. A linear relationship between peak current and lacidipine concentration was obtained. For analytical purposes, a calibration curve for lacidipine that covered concentrations between 5 x 10-6 and 2 x 10-6 was used. Detection and quantitation limits were 3.52 x 10-6 and 3.78 x 10-6M, respectively. The repeatability of the measurement was 2%. On the basis of the voltammetric response, we also developed high-performance liquid chromatographic methods with electrochemical detection. For comparative purposes, we also developed a spectrophotometric method.