Isotope profiling as a counterfeit drug detection tool

Researchers in Germany have developed a method of identifying the source of pharmaceuticals by measuring carbon, hydrogen and oxygen isotopes.

The technique could provide information about the provenance of drugs - including the raw materials and processes used in their production - and could be used to detect counterfeit medicines as well as other substances such as illicit cosmetics and food products.

Using a sample of 32 commercial ibuprofen products sourced from 13 countries, the scientists from the Helmholtz-Centre for Environmental Research in Germany measured the ratios of carbon, hydrogen and oxygen stable isotopes in the active ingredient using a technique known as isotope ratio mass spectrometry (IRMS).

Using the technology, there were able to distinguish between different samples of ibuprofen and could group them into five groups based on their synthetic process the raw materials used.

While laboratory techniques such as near-infrared spectroscopy and liquid chromatography-mass spectrometry can provide evidence of falsification, they do not allow "authentication of the origin of the active substance itself, distinguishing synthetic versus raw natural origins of materials, or detecting patent infringement for generic medicines," they write.

IRMS was chosen over other technologies such as nuclear magnetic resonance (NMR) spectrometry as it requires less time to process samples, is cheaper and can be conducted on a smaller test sample.

"Multidimensional isotope fingerprinting appears to be specific for sources and may be a useful tool to increase the transparency of manufacturing processes of ibuprofen in future," conclude the authors.

The research is published in the Journal of Pharmaceutical and Biomedical Analysis.