NQR spectroscopy promising for fake drug detection

Researchers at King's College London in the UK have developed a new portable device to detect counterfeit medicines which could be superior to current approaches.

The team - led by Professor Kaspar Althoefer and Dr. Jamie Barras of King's College London in the UK - has just published a study looking at the use of nitrogen-14 nuclear quadrupole resonance (14N NQR) spectroscopy to analyse a counterfeit version of malaria drug Metakelfin (pyrimethamine and sulfalene).

NQR spectroscopy is a non-destructive, non-chemical technique that allows a suspected counterfeit to be scanned and compared to a genuine medicine in a few seconds, with greater accuracy than other non-destructive techniques such as near infrared (NIR) and Raman spectroscopy.

The advantage of these spectroscopy approaches over invasive chemical approaches lies in their speed - it can take several days to get results back from a lab - as well as avoiding the scenario in which law enforcement are left with a bill to replace genuine product that has been sampled and used for analysis.

The KCL team have developed a briefcase-sized prototype of the NQR device, with around £475,000 ($730,000) in funding from the Wellcome Trust, that can be used to screen medicines in the field and not only identify the presence of an active pharmaceutical ingredient (API) but also provide a quantitative measurement.

The latest study - which has just been published on the Analytical Chemistry journal website - showed the device was able to determine that the fake Metakelfin product contained around 43 per cent of the API found in a genuine product.

NIR and Raman spectroscopy was also able to distinguish the counterfeit and genuine product, but without the quantitative reading, and in general these technologies are more suited to checking individual pills or loose powders, according to the team. NQR on the other hand can be used to examine bulk pills - i.e. a full bottle or complete blister pack - as well as shipping packs containing multiple bottles or blisters or drums of loose material.

Earlier successful tests of the device have looked at the antibiotic ampicillin and painkiller paracetamol, and the team intends to demonstrate proof-of-principle by developing a database of spectra from the World Health Organisation's list of essential medicines.

NQR has some limitations, however. For example, it can be used to fingerprint crystalline solids but will not work with liquids or amorphous solids and can’t scan through fully-metallic packaging.

The KCL team are hoping to develop a smaller, lighter and cheaper version of the device - with extended battery life - to make it more appealing as a field tool.