The traceability of a given product may be defined as the �ability to trace the history, application or location of manufactured or distributed products�. Counterfeits based on deliberate copying of processes or on the infringement of current patents for generic medicines are not straightforward to detect, unless the molecular probe is the active molecule itself (API). In this context, impurity profiling is limited. Techniques employing stable isotope analyses, in contrast, deal with the API itself, and are able to strip down the atomic composition of a given molecule. Such an intimate constitution is unique, and therefore can be used as a means to characterize the drug substance at the different stages of its history.The possibility of measuring site-specific 13C/12C ratios (quantification of each isotopomer) directly using 13C NMR has been established recently. The main difficulty of isotopic 13C NMR is meeting the requirement for a high level of precision: better than 1�!Recent technological developments have made further improvements, specifically by the exploitation of polarization transfer techniques, in which the abundance of the 1H atom is exploited to enhance sensitivity. Thus 13C isotopic profiles of ibuprofen and naproxen were obtained with the required precision and within a reasonable measurement time. The perspective to use 13C isotope analysis by 2D NMR has also been demonstrated with an 1H-13C HSQC experiment. This is very valuable for resolving crowded spectral regions.The representation of the data can be considered as analogous to that carried out in 'omic' approaches: comparison of data built up from a multiplicity of variables and collected from several samples using the same protocol for which the precision has been established. Thus the isotope profile can be considered as an 'isotopomic' study. This is a promising generic approach for forensic issues.

Intramolecular isotope profiling:  An efficient tool to fight against counterfeiting

246th National Meeting (2013)

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