Health

Why 361 needles are better than one

baby injection Image copyright Getty Images
Image caption Many adults, as well as children, dislike needles

One in 10 of us are said to have a fear of the hypodermic needle, a necessary but frequently uncomfortable fact of medical life.

While the needle is an efficient way to administer drugs and take samples for analysis, it still involves sticking a sharp bit of metal into the body.

This is problematic for many children, but particularly premature babies.

Since they are typically ill, premature babies are given a lot of medicines. But, because of their vulnerability, doctors need to take frequent blood samples as to ensure they get the right dose.

This could come in the form of regular injections, or the insertion of a permanent cannula, a procedure which is difficult enough to administer in grown adults.

'Like a cat's tongue'

Many researchers have tried to find an alternative solution.

Now, Prof Ryan Donnelly from Queens University Belfast and his team think they have come up with a solution. Not one needle, but 361.

The device looks like a small, clear plastic patch about half a centimetre across, which easily sits on the tip of your finger. One side looks quite rough.

Image copyright Queens University, Belfast
Image caption Microneedle patch compared to traditional needle

"It's a patch with 361 tiny, individual needles on it," explains Prof Donnelly.

The patch feels slightly rough to the touch, something akin to Velcro or a cats tongue. But the individual needles are extremely hard, and sharp at the tips.

Unlike normal hypodermic needles, these microneedles only penetrate the top layer of your skin. They don't contact the nerves, which is why you feel no pain. Nor do they go into your blood vessels.

Instead they collect the so called interstitial fluid which surrounds the cells in the outer layer of skin.

This fluid contains all the information the doctor requires.

'Very distressed'

Image copyright Getty Images
Image caption Crying newborn receives his first vaccination

This is good news for adults, but could be revolutionary for premature babies.

Dr Aaron Brady, a pharmacist recently recruited to the team has direct experience of working in neonatal care.

"Neonates, babies up to 28 days, have a very small blood volume - about the size of a drinks can.

"Quite often they'll need to have their blood monitored four times a day. If we can use these microneedles instead, we don't have to take any blood at all."

Dr Brady adds: "There are real problems associated with hypodermic needles, such as scarring and bruising.

"Using microneedles instantly eliminates any issues with scaring, bruising and damage to tissue."

Parents are very much in favour of something that could be applied as easily as a sticking plaster because, as Prof Ryan says, they become "very distressed" by the invasive medical procedures their children have to be subjected to.

Sofie Backstrom's daughter Freja has just turned one, but she was born three months prematurely at 26 weeks.

"When she was born she had blood samples taken almost daily for the first three months," says Sofie.

She still has injection scars from that time.

"They're mainly on the back of her hands and feet but on her knees and elbows too - about 20 scars on each."

Sofie would have welcomed a pain-free alternative.

"I think it's always worse for the parents - you don't want to see your child getting stabbed."

Drug delivery

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Media captionPlastic patch promises pain free injections

Prof Donnelly and his team aren't the only ones developing an alternative to injections. Several groups around the world are working on similar technologies, including Linda Klavinskis, an immunobiologist from Kings College London.

Microneedles can also be used for drug delivery and she is very excited about their potential. "One of the most profound effects will be the ability to deliver vaccines at a reduced cost.

"Microneedles are very simple, you don't need specially trained staff and they won't need any of the paraphernalia of a conventional vaccine."

Compounds can be incorporated into the polymer patches when they are made, and are slowly released into the body once they come into contact with the interstitial fluid.

Keeping cool

Prof Donnelly's team have used the patches to administer everything from insulin to ibuprofen.

Microneedles could also do away with the need to refrigerate vaccines.

Most vaccines need to be kept cold to stay effective and to prevent bacterial growth.

Trapped inside the polymer patches the vaccines should be stable in a dry state, even at warm temperatures.

It makes the needles particularly useful for vaccination campaigns in remote areas, where delivering and storing conventional liquid vaccines can be a challenge.

Prof Donnelly says: "Up to 50% of vaccines do not work in the developing world, because they've inadvertently been allowed to warm beyond 38C, or they've been frozen by mistake, which can damage the vaccine.".

If a patient receives a vaccine that hasn't been refrigerated properly it may not work and could lead to septicaemia and even death.

Needle stick injuries

Image caption Used microneedles are too soft to cause needle stick injuries

The microneedles are also much safer than conventional hypodermics.

Every year, around two million health workers get injured by sharp needles after they've been used. Contracting HIV or hepatitis this way is not uncommon.

The patches are made of hydrogel - similar to the material used in disposable nappies or contact lenses. Although hard when inserted, they soften as fluid is absorbed and can no longer cause injury.

It also prevents them from being used again. The WHO estimates that every year 21 million cases of hepatitis B can be attributed to needle reuse.

"Even after one minute in skin the micro needles are too soft to be reinserted and hence there is no danger associated with them." Prof Donnelly says.

The microneedles are still being developed and need to undergo rigorous clinical trials.

However Prof Donnelly is optimistic that they will soon be a common sight around the world.

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