In this article, for the first time, the analytical method for determination of a novel antagonist of A2A adenosine receptors (8-(4-methoxyphenyl)-4-oxo-4,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazine-3-carbohydrazide, namely IMT), which can be used as a drug for liver diseases, was presented. For this purpose a commercially available boron-doped diamond electrode (BDDE) in combination with differential pulse voltammetry (DPV) was applied. It was found by cyclic voltammetry (CV) that IMT displays at BDDE, as a sensor, two well-defined oxidation peaks at potentials of 0.81 and 1.18 V and one reduction peak at 1.1 V vs. Ag/AgCl in 0.1 mol L−1 acetate buffer (pH 4.5±0.1). The oxidation and reduction mechanism of IMT was proposed. The developed DPV method allowed the successful determination of IMT in the range of 0.05–50 μmol L−1 with detection limit equal to 0.0094 μmol L−1 and without any chemical modifications and electrochemical pretreatment of the electrode surface. The proposed procedure allows the determination of IMT in vitro directly from urine samples.