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Briefcase encounter: An invention to detect fake drugs

12 Nov, 2012

The ‘briefcase’ which can detect counterfeit medicines through their packaging.

A new invention to detect counterfeit drugs is being developed with Wellcome Trust support at King’s College London (KCL). I went to meet Professor Kaspar Althoefer and Dr Jamie Barras, who are presenting their work for the first time at a conference in the United States today, to find out more.

The large metal briefcase reminded me of something out of an 80s sci-fi movie. With just two buttons and a small black screen, I was sceptical as to whether this could really work. But Jamie Barras, Research Fellow at KCL, popped in some paracetamol tablets and within a matter of seconds a reading had been taken.

The innovative case can detect whether a drug is the real deal or a fake. There are no chemical tests involved and you don’t even have to take the tablets out of their blister packets to take the reading. So how does it work? The detector uses radiofrequency waves to excite the active ingredient of the drug, which then releases energy and produces a spectrum unique to that molecule.

This type of spectroscopy is known as nuclear quadrupole resonance (NQR). It is similar to nuclear magnetic resonance (NMR), except NQR doesn’t involve an external magnet. In NMR, a magnetic field surrounding the compound is necessary to alter the orientation of the nucleus so that an energy change can take place when radiofrequency waves are applied.

A magnet isn’t necessary in NQR because the structure of the crystal surrounding an atom has already changed the orientation of the nucleus. When radiofrequency waves are applied, an energy change takes place. Then, when the nucleus reverts back to normal, the energy change can be measured. This is true of certain atoms in a crystal, such as nitrogen, bromine and chlorine, which are present in about 80 per cent of medicines.

The energy spectrum is compared to that of a genuine sample: if it doesn’t match, we know the drug is counterfeit. One particularly useful feature is that the measurements are quantitative: the energy released decreases linearly with the mass of the sample. That means that it is easy to detect a tablet of the right size and weight but with a smaller mass of active ingredient.

One specific example the group tested was an anti-malarial drug, Metakelfin. It was developed as a promising new alternative to existing anti-malarial treatment but, once on the market, large quantities of counterfeits were produced. Fake drugs not only deprive people of the right treatment, they can also increase rates of drug resistance if small, ineffective amounts of medicine are used. Kaspar Althoefer, Head of the Centre for Robotics Research, and his team tested counterfeits against genuine Metakelfin on the prototype of their detector. They found that the counterfeits gave off the correct signal (at the correct frequency) but the size of the peak was smaller. This proved that although the active ingredient was present, there was a smaller mass of it than there should have been for the proper dose.

The group headed by Kaspar began looking into using NQR for testing pharmaceuticals around 20 years ago. But, Jamie explained, it was difficult to convince the scientific community: “There is a lot of inertia in this [pharmaceutical] industry to bringing in a new standard. So we started to look at counterfeit medicines as the market was a lot less crowded.” Just six months after they began their research, the EU put out a call for new techniques to detect counterfeit medicines.

At the moment, the most popular and accurate techniques used to detect counterfeit drugs are chemical or optical tests. Both involve at least opening the packet of the drug, and often destroying the sample itself. With NQR the packet can stay intact, so if the counterfeit test is negative, the drugs can go back on the shelf. When compared with the leading chemical test, the results were almost identical, although NQR did have a slightly higher error. But their test takes only 15 seconds compared with what can take hours of testing in a lab.

So is there any downside? The technique only works on solids and suspensions, not solutions or liquids, because it requires a crystal structure. It also won’t work through metal packets, only plastic and paper. But Jamie’s biggest problem wasn’t with the machine itself, it was how he could test it.

Counterfeit drugs are quite hard to find, for obvious reasons, but even getting sufficient quantities of legal medicines is a problem. Jamie has to stop off at every pharmacy on his way to work to avoid raising suspicions about the unusually large quantities of paracetamol he keeps buying. And it looks even stranger when he’s buying several bottles of Calpol, a suspension of paracetamol used to treat children. But luckily this problem hasn’t held them back too much.

The team hope, now that the prototype is ready to be presented, the technology can go on to be used by governments and non-governmental organisations, reducing the time it takes to test counterfeit medicines and the number of samples that have to be destroyed unnecessarily. It may look like it’s a prop from an old sci-fi film but it does work in the real world, and could be the future of how we find the fakes among the genuine medicines.

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