Brinzolamide (BRZ) is an antiglaucoma drug also used by athletes for doping purposes; therefore, it is
prohibited by the World Anti-Doping Agency. Consequently, the presence of BRZ or its metabolites in
athletes' urine constitutes a violation of anti-doping rules. The current work presents a novel
electrochemical method that assesses the effectiveness of mercury oxide nanoparticles (HgO-NPs) and
a mercuric chloride–1,10-phenanthroline complex (HgCl2–Phen complex) as sensors for BRZ analysis. A
comparative analysis revealed that the synthesized HgCl2–Phen complex exhibited superior sensitivity
and efficiency in determining BRZ levels. The properties of the modifiers were extensively characterized
using elemental analysis, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and
scanning electron microscopy (SEM). Furthermore, electrochemical characterization was conducted
using square wave voltammetry (SWV), cyclic voltammetry (CV), and electrochemical impedance
spectroscopy (EIS). The electrode showed a good response for SWV evaluations of BRZ in
a concentration range of 0.1 to 6.0 mmol L−1, with very low limits of detection (0.01 mmol L−1) and
quantitation (0.031 mmol L−1). The method's applicability was validated by detecting BRZ in urine samples
from healthy human volunteers and in pharmaceutical eye drops. Additionally, the practical effectiveness
of the method was assessed using the blue applicability grade index (BAGI). The key advantages of this
sensor include its simple manufacturing process, as well as its remarkable sensitivity and selectivity.