Terahertz testing could fight faked meds, says scientist

A researcher in Finland has suggested that an analytical technique based on terahertz radiation could be a useful, non-invasive way of identifying pharmaceutical tablets.

Prince Bawuah from the University of Eastern Finland showed that using terahertz radiation – which is at the far end of the infrared spectrum and invisible and safe for human beings – it is possible to gain deep insights into the properties of tablets, including their ingredients, the way the constituents are distributed across the tablet and other measure such as mechanical strength.

Aside from general quality control testing, he suggests that "another important application is that this method can detect counterfeit and substandard tablets". They give the example of fake antimalarial tablets which are "flooding the markets in developing countries, where counterfeit drugs are a major cause of mortality."

Working with scientists at the University of Cambridge, UK, and in Switzerland, Bawuah successfully showed that the technique can detect the porosity, weight and height of tablets. The technology could be an alternative non-destructive approach for quality screening of tablets and replace destructive techniques such as mercury intrusion porosimetry.

Other techniques, such as near infrared (NIR) and Raman spectroscopy, also have disadvantages in that they give complex spectra that require relatively sophisticated statistical tools to analyse the results. They require high-power lasers that can bleach tablets – which can be a consideration in quality control settings.

On the downside, terahertz scanners tend to be more bulky and require a controlled measuring environment.

"Since the majority (about 80 per cent) of administered drugs are tablets, there is a significant need for a process analytical technology (PAT) tool that will permit the screening of individual pharmaceutical tablets before they reach end users," according to Bawuah.

He says the work is a promising feasibility study that has brought to light the inherent ability of assessing many but important tablets parameters through a single terahertz transmission measurement.

"This 'many-in-one' technique… will ensure the safety, quality and efficacy of pharmaceutical solid dosage forms due to its ability to assess each tablet," he concludes.