Newly Developed Nano Sensitive Carbon Paste Electrode Modified with Silver Sulphadiazine and Zinc Oxide for Voltammetric Determination of Loperamide Hydrochloride in Pharmaceutical Formulation and in Human Plasma

A simple electrochemical procedure was developed for the electrochemical determination of Loperamide hydrochloride (LOP). A square wave voltammetric method was applied to determine LOP in its pure form, pharmaceutical formulation, in presence of co-administered drugs omeprazole, trimebutine, and naproxen and in human plasma. In the applied method, a newly fabricated carbon paste electrode chemically modified with silver sulfadiazine and zinc oxide was used. Experimental parameters such as pH of Britton-Robinson buffer, scan rate and applied current potential of the electrode surface were optimized. The morphological structure of the newly fabricated electrode was illustrated using transmission electron microscopy. Using Britton–Robinson buffer of pH 8.00, LOP showed an irreversible anodic peak of 0.827 V. The manufactured sensor displayed high sensitivity and optimum charge/electrode kinetic transmission. Linear calibration curve was obtained between the peak current and the corresponding concentration of LOP over the range (14.00 × 10⁻¹²− 1.00 × 10⁻⁴M) with low detection limit of about (4.00 × 10⁻¹²M) indicating good sensitivity. The proposed method was validated according to the ICH guidelines. The proposed sensor was also applied to determine LOP in human plasma after successfully validating the method according to the FDA bioanalytical methods guidelines. The greenness of the method was assessed using the Analytical Eco-Scale approach and the results reveal that the developed method is not only greener and uses non-hazardous chemicals than the previously reported HPLC methods for LOP determination in biological fluid but also can be used in the quality control laboratories for LOP determination in pharmaceutical formulation and in human plasma.