Pharmabiome analyses in tandem with chemometrics can help trace the provenance of falsified medicines: A proof-of-concept study

A lack of robust analytical approaches limits our ability to investigate the clandestine manufacturing origins of falsified medicines. We conducted a proof-of-concept study to test the feasibility of geolocating the production sites of falsified medicines, based on the identification of site-specific biological and chemo-isotopic features using a combination of environmental DNA metabarcoding, Direct Analysis in Real Time - Mass Spectrometry and Isotope Ratio Mass Spectrometry as profiling techniques. We produced tablets at two distant locations (England vs. Thailand), using controlled manufacturing methods, excipient composition and environmental conditions. Sets of tablets produced at separate locations showed distinct bacterial and eukaryotic diversity, particularly influenced by the incorporation of water used during tableting and the background environmental biosignatures of the production site. Tablets showed corresponding site-specific chemometric profiles, but the factors contributing to the observed chemical differences were unclear. When reference samples of known origin are available, our study suggests that site-specific biological and chemical features can be used in modelling approaches to successfully predict product origin. We developed a new mapping approach to exploit the geographic information within the eukaryotic pharmabiome of the falsifications; based on eDNA-derived species identification and the integration of publicly available species distribution data. In the absence of reference samples of known origin, the application of this workflow to our dataset provided partial clues about the product's origin, with limitations likely due to taxonomic resolution and the presence of species with wide distribution ranges. Collectively, our research provides experimental support for the development of integrated, multifaceted tools for tracing the origin of falsified medicines, advancing efforts to combat this pervasive but neglected global health problem.