Needles are something of a sore point for many people. From phobias to infections, accidents and misuse, they deliver many health negatives as well as positives. Yet, with an estimated 12 billion needles entering our arms, bums and thighs each year worldwide, injections are one of the most frequently used medical procedures.
Last week, the results of trials into insulin inhalers replacing injections for diabetes were presented at a conference organized by Diabetes UK, emphasising the desire for alternative modes of drug delivery. But for decades, needle-free injection devices have been developed for the mainstream market without ever being introduced.
The latest was devised by a team of undergraduate bioengineering students at the University of California, Berkeley. Their MicroJet injector uses an electronic actuator instead of a needle to propel drugs through the surface of the skin, in a similar way to an inkjet printer.
While it hasn't yet been tested on humans, they claim their invention is an improvement on previous devices.
"The big reason current injectors aren't in use is because they aren't reliable," says researcher Marcio von Muhlen. "Having the idea of a bunch of people lining up and getting a shot, which has been around for decades, doesn't work because people have different thickness of skin."
The MicroJet's source of power is electrical rather than mechanical, and when the students tested it on a skin-like gel, they found it gave greater continuous control of liquid.
"When a doctor injects you with a needle, he is very sure he is getting into your arm," says Von Muhlen, 21. "So they jam the thing in there, which causes a lot of the pain. Our idea is not to target that application as that would require constant adjustments and knowledge of each person's arm.
"The main potential use is for projection into a sensitive part of the body -- for example, arthritis patients or those who need anti-inflammatory drugs in their hands. Needles cause damage to the surrounding tissue. But if you had a reliable injector that you can tune to that area of the body, that would be very effective," he says.
More than 7 million people in the UK have long-term health problems due to arthritis or a related condition, almost half of whom take medication. Some, such as Linda Deeley, 65, from Oxfordshire, northwest of London, have to endure painful injections into their joints. Deeley was diagnosed with arthritis seven years ago and has had three injections into her knee joint.
"It was not very successful," she says. "The last needle didn't go in the right place and it hurt like hell... If they can do anything without needles, that's fine by me."
Dr. Madeline Devey, scientific adviser to the Arthritis Research Campaign in the UK, agrees.
"It sounds like a good idea," she says.
"One of the big difficulties with joint injections is that you can't get the needle into the right place easily." This can lead to a lot of pain, or the drug not reaching the intended area.
The MicroJet could also be used for eye treatments. Researchers would like to test eye drugs for the elderly, says Von Muhlen, but clinical trials are being held up because the drugs can be difficult to deliver.
"What excites me is new applications that aren't being used because of the limitations in current needle-free technologies," he says.
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