NEWS: BBC: Child's toy inspires drug device

[janet paterson <janet313@xxxxxxxxxxx>]

BBC News Online: Health

Thursday, 8 March, 2001, 01:06 GMT

Child's toy inspires drug device

A children's bath toy was the inspiration for a new device that could
revolutionise the way drugs are delivered to the body.

Scientists are developing an implant that uses spongy artificial muscles to
release drugs in amounts that match exactly the body's needs.

New Scientist magazine reports that the developers hope their new
"controlled release" technology will be ideal for delivering repeated,
measured doses of drugs - for instance the insulin that diabetics need to
regulate blood sugar.

One of the first applications of the new technology, however, is likely to
be more unusual. It is planned to use it to deliver melatonin to astronauts
to regulate their sleep patterns.

Researchers have long sought a method of matching drug doses precisely to
the fluctuating needs of the body of a patient with a long term disorder.

This is impossible using pills and injections as doses tend to be set in
advance for a fixed period.

The new device has been developed by materials scientist Dr Marc Madou, of
Ohio State University in Columbus, US.

He designed an implantable capsule about the size of a matchstick that is
perforated with microscopic holes, each opened or closed by a small ring of
artificial muscle.

The muscles shrink and swell on command, behaving like tiny trapdoors to
release variable amounts of medication.

Sponge man

Dr Madou got the idea from a toy sponge man that expands to several times
its size when soaked in water.

It set him wondering if sponge-like materials, called porous hydrogels,
could be used in a similar way to open and shut a drug delivery trap.

Porous hydrogels are full of microscopic holes and, like the toy, they are
capable of expanding to several times their normal size.

Dr Madou created an artificial muscle by attaching a piece of hydrogel to a
backbone of conductive plastic.

Current flowing through the plastic makes the hydrogel shrink or swell.

Applying a voltage makes the muscle contract, releasing the drug. Reversing
the voltage makes the muscles expand, cutting off the flow.

Dr Madou said: "The hydrogel is like a miniature sphincter only it's
controlled by a battery."

The next step is to develop a biosensor that will poke outside the capsule
to detect current conditions within the body.

For instance, in diabetics it would measure levels of blood sugar to
determine how much insulin needs to be released by the implant.

A spokesman for Diabetes UK said: "People treating their diabetes with
insulin injections need to vary their dosage according to what they are
eating or what they are doing.

"This makes controlling their blood glucose levels very difficult.

"A device that could sense how much insulin is required and automatically
release that amount would be a major breakthrough.

"However this idea is at a very early stage and it would be quite a few
years, if at all, before any such device could benefit people with
diabetes."

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Related to this story:
GPs 'give children unproven doses' (20 Nov 00 | Health) Made-to-measure
medicine (08 Apr 00 | Health) Cancer drugs tracked around body (01 Mar
01 | Health)

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Internet links: New Scientist | Ohio State University | Diabetes UK |

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