Technology: This won't hurt . . . at all

2019-03-01 10:05:00

By ANDY COGHLAN People who are terrified of injections can take heart: a British firm has developed a disposable syringe that administers drugs painlessly, without using a needle. Compressed gas within the device fires drugs through the skin at two to three times the speed of sound. ‘It feels like a puff of air on your skin,’ says Elspeth Bellhouse, who is marketing director at Oxford BioSciences, the company that developed the device. Although the new syringe costs three times as much as conventional disposable syringes – about 50 pence compared to 15 pence – she believes it could make them obsolete in a wide range of applications: examples include mass vaccinations and the daily insulin injections that diabetes patients need. ‘It’s safer, because it doesn’t break the skin and there’s no problem with the disposal of needles,’ she says. This cuts the risk of accidental infection with bloodborne viruses. Another advantage of the needleless syringe is that the drugs it delivers are in powder form. Many drugs become chemically unstable when they are dissolved in water. In hot climates, solutions of drugs and vaccines for injection can decay unless they are refrigerated. This poses storage and distribution problems in tropical countries. Powders are easier to transport and may not need refrigeration. The new syringe is a pen-shaped device with a button on the top. When pressed, this pierces the bottom of a vial of compressed gas, allowing it to surge down into a chamber containing the powdered drug. The gas expands through a specially shaped nozzle, reaching supersonic speed. The jet of high-speed gas gathers up the drug particles and propels them into the skin over an area about an inch in diameter. ‘When it’s released, there’s an audible whoosh,’ says Bellhouse. ‘It sounds simple, but the control of the flow of gas is very important.’ To deliver a drug effectively, the device must get the drug particles through the stratum corneum, a thin but extremely tough layer of dead cells and fibrous keratin on the surface of the skin. ‘Once it’s got through the dead layer, the drug soon dissolves through the underlying cells and into the capillaries,’ Bellhouse explains. Oxford BioSciences believes it may be possible to develop a version of the syringe that will push the drug deep enough for intramuscular injections. But it would not be precise enough for intravenous injections, and needle-based syringes will remain the only way to administer fast-acting drugs such as morphine for pain relief. It will be three to five years before the devices see clinical use. ‘Regulatory authorities have not approved any drugs as injectables in powdered form,