Invisible weapons to fight fake drugs

 

THE perils of counterfeit drugs go way beyond being ripped off by dubious online pill-pushers. Malaria treatments containing no active ingredients, out-of-date chemotherapy drugs and diabetes medication with lethal levels of compounds that encourage insulin release have all recently been found on sale in legitimate outlets. Now the pharmaceutical industry is trying to fight back by making it easier to spot fakes.

The World Health Organization estimates that 50 per cent of all medicines sold online are worthless counterfeits. In developing nations fake pills may account for as much as 30 per cent of all drugs on the market. Even in the developed world, 1 per cent of medicines bought over the counter are fakes.

Some key events illustrate the risk these pose. In Nigeria, 2500 children died in 1995 after receiving fake meningitis vaccines. In Haiti, Bangladesh and Nigeria, around 400 people died in 1998 after being given paracetamol (acetaminophen) that had been prepared with diethylene glycol – a solvent used in wallpaper stripper. The fakers are nothing if not market-aware: in the face of an outbreak of H5N1 bird flu in 2005, they began offering fake Tamiflu.

What can be done? The WHO coordinates an umbrella body called the International Medical Products Anti-Counterfeiting Taskforce (IMPACT), an industry initiative that issues alerts when it finds anomalies in the medicine supply chain. Such events include sudden drops in wholesale prices, hinting at fakes coming onto the market, or the mimicking of anti-counterfeiting features on packaging, such as holograms or barcodes, says Nimo Ahmed, head of intelligence at the UK’s Medicine and Healthcare Products Regulatory Agency.

Drug packaging is an obvious avenue for counterfeiters to exploit. Boxes and blister packs are usually easy to copy and the repackaging of drugs is not necessarily illegal. Indeed it is standard practice in the pharmaceutical industry as countries have their own rules on, for example, the quantity of a drug that can be supplied in a pack.

What’s really needed, says Dean Hart of NanoGuardian, a nanotechnology firm based in Chicago, Illinois, is a way to authenticate the drugs inside the packs. The company is aiming to do that by printing microscale and nanoscale information on pills and capsules.

The idea is based loosely on technology developed by NanoGuardian’s owner, NanoInk, which pioneered a process called Dip Pen Nanolithography. DPN was originally designed to drop biological samples such as individual stem cells into test wells. NanoInk has adapted the technology to create a print head 15 nanometres across at the end of a nanoscale arm steered by an electric field. The tip can incorporate hollows that hold a minuscule volume of a substance to be “printed” onto a surface.

“We are using a lot of what we learned building those nanoscale tools to write on pills, capsules, vial caps and pre-filled syringes,” Hart told New Scientist.

Nothing is added chemically to a tablet in the process, he stresses. Instead, they use a nano-imprinter whose precise mode of operation is confidential. First, they use their imprinting pen to create a microscale mark – perhaps the drug company’s logo – that is visible only using a high-magnification eyeglass, or loupe. “That gives you a very good indication that the drug’s authentic,” says Hart.

Inside the logo they then imprint a 350-digit nanoscale random number that is changed daily. That number is recorded on the drug-maker’s database alongside information on where the batch was made, where it was destined to be sold and the drug’s expiry date.

Should investigators find out-of-date drugs on sale, they can send them to NanoGuardian to read the number and trace where that consignment was originally shipped to. The technology, which has been approved by the US Food and Drug Administration, will debut later this year on drugs made by Capsugel, a division of pharmaceutical giant Pfizer.

NanoGuardian is not alone in trying to apply a benign ID mark to tablets. At Ghent University in Belgium, nanomedical engineer Stefaan De Smedt is developing an edible polymer fibre that can be labelled with a telltale fluorescent barcode along its length and incorporated into a pill (Advanced Materials, DOI: 10.1002/adma.201000130).

De Smedt is experimenting with cellulose and polystyrene-based fibres. To make them, he takes a solution of the fibres and adds fluoroscein, a fluorescing agent used in medical tests. The solution is then turned into microfibres using a process called electrospinning, where the solution is squirted from a charged syringe tip onto a rotating wheel on which fibres adhere like sticky tape on a roll.

To write barcode-style stripes into these fibres – perhaps encoding information on the type of drug, its source and expiry date – De Smedt illuminates them with laser light at 488 nanometres, a wavelength which locally bleaches the fluoroscein in the fibres, creating dark stripes. The fibres are then cut by laser into 10-micrometre lengths for dropping into the mixture from which the drug will be made.

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