The interaction of the antiparasitic drug nitazoxanide (NTZ) with salmon sperm double strand deoxyribonucleic acid (ss-ds-DNA) has been studied using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) at screen printed carbon electrode (SPCE). NTZ shows two irreversible oxidation peaks measured in 0.02 M phosphate buffer (pH 4.0 and 7.4). UV/Vis spectroscopy was also employed to probe the interaction between NTZ and ss-ds-DNA. From the CV data, the diffusion coefficients were found as 5.1 x 10(-7) and 4.9 x 10(-9) cm(2)s(-1) for NTZ and NTZ-DNA, respectively. Based on the CV and spectroscopic results, the binding constant between NTZ and DNA was calculated to be 4.1 x 10(5) M-1 and 5.0 x 10(5) M-1, respectively. The interaction as a sum of intercalation and groove binding modes was concluded. A procedure for the differential pulse voltammetric determination of NTZ at a screen-printed electrode surface modified with the ss-ds-DNA layer was also described. The method was applied for the determination of NTZ in spiked serum. (c) 2014 Elsevier Ltd. All rights reserved.