DNA-labelled excipients allow on-dose authentication of meds

DNA tags added to excipients during the manufacture of tablets remain stable and can be used for authentication – even after months of challenging environmental conditions.

The study conducted by scientists at King’s College London in collaboration with Dubai Police and Applied DNA Sciences – which supplied the tags – is thought to be the first to assess adding DNA markers directly into a powder excipient mix.

The researchers used standard pharmaceutical processing equipment to manufacture the 400mg lactose tablets, and found that the physical properties of the resulting pills – such as their hardness, uniformity and tendency to chip or crumble on compression – was unaffected by the DNA tags.

That was the case even after they were subjected to six months of elevated temperature and relative humidity – 40 degrees C and 75 per cent respectively – to simulate the conditions that medicines can face when being shipped and stored in some areas of the globe.

The DNA tags did show some evidence of denaturing over the course of the study, but were still able to be detected using Applied DNA’s SigNify qPCR lab instrument at the end of the storage period. They were also found to be distributed evenly throughout the tablet.

Use of the tags could allow pharma companies to check whether a suspect medicine is genuine or falsified, even if it is discovered as a loose tablet without any packaging.

Current efforts to guard against counterfeit medicines often focus on adding serial numbers and authentication features to the secondary packaging which – while clearly providing a substantial improvement in patient safety – do not guarantee the authenticity of the medicines within.

Counterfeit medicines are sometimes encountered without packaging, for example when opioid analgesics are diverted for misuse or counterfeit versions are sold to drug users or – likely less commonly – when fake drugs are inserted into genuine packaging.

The DNA tags meet US FDA guidance finalised in 2011 on physical-chemical identifiers (PCID), defined as a substance or combination of substances possessing a unique physical or chemical property that can be used to identify and authenticate a drug product or dosage.

Companies working in the area of on-dose authentication of oral medicines include Authentix, Colorcon, InfraTrac and TruTag, amongst others.

In the latest study, the DNA tags were detected by crushing or simply swabbing the surface of a tablet, which means that unlike other PCIDs such as inks, pigments, and molecular taggants the testing doesn’t involve destroying the pill, leaving it intact for further investigation.

“The DNA molecular tags, and the processing technology investigated here, produced traceable tablets that could withstand accelerated … storage conditions,” write the authors of the study, published in the International Journal of Pharmaceutics.

“On the basis of these results it would appear that DNA molecular tags could feasibly be applied within the pharmaceutical development cycle when a new medicine is brought to the market so as to mitigate the risk and dangers of counterfeiting.”