Electrochemical study of hydroxychloroquine and its determination in plaquenil by differential pulse voltammetry.

Hydroxychloroquine (HCQ) is a halogenated aminoquinoline that presents wide biological activity, often being used as an antimalarial drug. The electrochemical reduction of HCQ was investigated by cyclic voltammetry and chronoamperometry using glassy carbon electrodes. By cyclic voltammetry, in acid medium, only the cathodic peak was observed. The electrochemical behavior of this peak is dependent on pH and the electrodic process occurs through an E(r)C(i) mechanism. The electron number (1e) consumed in the reduction of HCQ was obtained by chronoamperometry. A method for the electrochemical determination of HCQ in pharmaceutical tablets was developed using differential pulse voltammetry. The detection limit reached was 11.2 microg ml(-1) of HCQ with a relative standard deviation of 0.46%. A spectrophotometric study of HCQ has been also carried out utilizing a band at 343 nm. The obtained detection limit and the relative standard deviation were 0.1 microg ml(-1) and 0.36%, respectively. The electrochemical methods are sufficiently accurate and precise to be applied for HCQ determination, in laboratorial routine, which can be used to determine the drug at low level.