Painless microneedle flu vaccines

Main Category: Infectious Diseases / Bacteria / Viruses
Also Included In: Flu / Cold / SARS
Article Date: 22 Dec 2003 - 0:00 PDT


Researchers at the Georgia Institute of Technology have been developing needles that are smaller than the diameter of a strand of hair. When placed on the underside of a patch, an array of the microneedles can deliver medicines nearly painlessly and without the help of a health professional.

'Some people might not feel a thing,' said Mark Prausnitz, a biomedical engineer at the Institute. 'It depends on the size of the needle and the person. What hurts one person won't hurt another.'

Pain perceptions aside, no microneedle will feel anything like the jab from a typical hypodermic.

Prausnitz says his test subjects claim they don't feel a thing (granted, they're hearty graduate students). The hope is by avoiding the 'ouch' in drug delivery, people might be more willing - and more able - to make sure they are protected.

Choice of Materials: Metal, Polymer, Glass

In their workshop, Prausnitz and his colleagues have been spinning, baking, glass-drawing and melting at microscopic levels to create an array of tiny needles from silicon, biodegradable polymers, metals and glass. Their creations range in size from 1 millimeter in length to only 25 microns - or about a third of the diameter of a human hair.

Prausnitz favors the metal microneedles for their proven compatibility within the body and for their strength - the pins are made from stainless steel and, in some cases gold.

'You really don't need much material, so it's not expensive,' he said.

Polymer needles also have an advantage, he says, because if a tip snaps off while inserted, the material can easily biodegrade. The team also created molds for the needles, making it possible for a company to mass produce them.

The Georgia lab has licensed the technology to a Massachusetts company, Biovalve, while other companies owned by 3M and Johnson and Johnson are tapping other labs to develop their own lines of microneedles.

None of the needles have yet been approved by the Food and Drug Administration for general use.

Prausnitz says when they do receive FDA approval, the needles could become instrumental during medical emergencies. Following a biological attack, for example, antibiotics or vaccines could be handed out in patch form so people could easily administer the treatment themselves.

'Almost anyone could do it - all it involves is sticking and unsticking a patch,' Prausnitz said.

Different Deliveries

The needles deliver medications in a variety of ways. Some are designed in hollow form and would work as a traditional syringe by injecting a medicine just under the skin's surface. Prausnitz points out the small needles might even be more effective than large hypodermics because they can deliver medicine to a group of immune cells just under the skin's surface that are an effective target for drugs.

Another possibility is using arrays of the microneedles to poke small holes in the skin. The small holes could then easily absorb medicine that's applied over the area.

The needles may also be coated with a drug, inserted into the skin and removed once the drug has had time to dissipate. Finally, Prausnitz's team is outfitting patches with needles and sensors for diabetics. The patches would sense when the person needs more insulin and deliver it automatically.

Poking even small holes in the skin may not sound pleasant, but since the needles are so small, all the pricking and injecting is virtually pain-free. In fact, when it comes to needles, much of the pain sensation may be in the packaging.

'People are conditioned to look at a hypodermic syringe and expect pain, so we'd want our delivery systems to look very different,' said Prausnitz.

Tiny Tube Delivery

Microneedles are just one way researchers are hoping to make drug delivery less painful.

Other projects include constructing carbon nanotubes into controlled delivery systems. Nanotubes are made from carbon sheets wrapped into cylinders that are extremely strong and extremely small at about one billionth of a meter.

A series of nanotubes are packed like straws in a box and placed on a patch for timed drug delivery. Another approach uses microscopic biocapsules that, when placed just under the skin, could deliver a constant amount of medicine over a long period.

If and when these products become available, people might have more reason to feel at ease when they're told, 'Now this won't hurt a bit …'

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