Identification of substandard and falsified antimalarial pharmaceuticals chloroquine, doxycycline, and primaquine using surface-enhanced Raman scattering

Falsified antimalarial pharmaceuticals are a worldwide problem with negative public health implications. Here, we develop a surface-enhanced Raman scattering (SERS) protocol to recognize substandard and falsified antimalarial drugs present in commercially available tablets. After recording SERS spectra for pure chloroquine, primaquine, and doxycycline, SERS is used to measure these drugs formulated as active pharmaceutical ingredients (APIs) in the presence of common pharmaceutical caplet excipients. To demonstrate the viability of our approach, a red team study was also performed where low-quality and falsified formulations of all three drugs presented as unknowns were identified. These data in conjunction with promising results from a portable Raman spectrometer suggest that SERS is a viable technique for on-site analysis of drug quality.