Detection of falsified clopidogrel in the presence of excipients using voltammetry

There has been a recent surge in the amount of substandard and falsified clopidogrel. Pharmacopeial based assays using high performance liquid chromatography and mass spectroscopy are widely used for the measurement of clopidogrel but are not accessible in low to middle income countries. Therefore, our study explored four different techniques (mid-infrared spectroscopy, thin layer chromatography, ultraviolet visible spectroscopy, and differential pulse voltammetry), which could be used in low to middle income countries. Differential pulse voltammetry showed the best performance for accurate and precise determination of clopidogrel in the presence of excipients. Clopidogrel tablets were fully crushed and sonicated in buffer for 30 seconds prior to differential pulse voltammetry measurements using a 3 mm glassy carbon electrode. Measurements were made without removing the excipients and the limit of detection was 0.08 mg ml^-1 and the sensitivity was 15.7 μA mg ml^-1. When conducting a blinded study, differential pulse voltammetry was able to identify varying types of substandard and falsified samples. Our findings highlight that voltammetry could be a vital analytical technique for the determination of substandard and falsified medicines in low- and middle-income countries.