Determination of disulfiram and diethyldithiocarbamate in plasma by high performance liquid chromatography with an electrochemical detection using a diamond electrode

Disulfiram (DSF), a drug approved for the treatment of alcoholism, has been increasing attention as an anti-inflammatory agent via inhibit cytoplasmic FROUNT, a common regulator of chemokine receptor CCR2 and CCR5 signaling. Although the determination of DSF in biological fluids, particularly plasma, is important for evaluating drug efficacy, rapid degradation of DSF by albumin often interferes with its accuracy and reproducibility. In this study, cost-effective, selective, and reproducible high-performance liquid chromatography (HPLC) using an electrochemical detector (ECD) equipped with a diamond electrode was used to quantify DSF and its metabolite, diethyldithiocarbamate (DDTC). The limit of quantification (LOQ) for DSF in an albumin-free solution using the HPLC-ECD method was 0.04 μg/mL; however, DSF was not detected in the serum spiked with DSF. Two forms of DSF metabolites, the free and albumin bound forms of DDTC, were detected as methyl-DDTC (MeDDTC) by methyl iodide treatment. The LOQ of MeDDTC in acetonitrile and serum determined using the HPLC-ECD method were 0.41 μg/mL and 1.22 μg/mL, respectively. Plasma MeDDTC was detected in rats that were orally administered DSF (1000 mg/kg) up to 48 h after treatment. This result suggests that HPLC-ECD with a diamond electrode is useful for determining MeDDTC for DSF monitoring in plasma.