http://www.dailymail.co.uk/health/article-4026284/Can-hi-tech-plaster-stop-fatal-blood-clots-cause-strokes-heart-attacks-new-patch-turbocharges-body-s-blood-thinning-molecules-making-defences-effective.html
- Millions are already taking tablets containing heparin to reduce the risk of clots
- The new patch automatically injects the same drug through miniature needles
- This prevents patients from taking too much, which can cause fatal bleeding
A high-tech skin patch could prevent deadly blood clots that cause strokes and heart attacks.
The
patch detects when a clot is in danger of developing and automatically
releases a blood thinner into the bloodstream in time to stop it.
It
does this through micro-needles in the patch which gently pierce tiny
blood vessels — called capillaries — just beneath the skin.
As
blood passes by, the needles — each one not much thicker than a human
hair — monitor levels of thrombin, a clotting agent which increases in
the blood when it is becoming dangerously thick and prone to clotting.
If
thrombin levels are abnormally high, tiny amounts of a drug called
heparin are released to thin the blood and reduce the clotting risk.
Heparin
works by 'turbocharging' the body's own blood-thinning molecule, called
antithrombin III, making it up to 2,000 times more effective.
Millions of people in Britain already take heparin tablets daily to reduce the risk of clots, or thrombosis.
Some
are prescribed it because they have atrial fibrillation, an irregular
heartbeat which can make blood pool inside the heart, increasing the
chances of a clot breaking away and travelling to the brain — causing a
stroke.
Others take the drug because they have already had a stroke and are at high risk of another.
Patients
who have had major surgery — such as hip or knee replacement — are also
put on short courses of heparin tablets or injections as immobility
puts them at high risk of a clot because blood pools in their legs.
But those on drugs such as heparin need frequent blood tests to ensure they are getting exactly the right dose.
Too
much medicine can cause potentially fatal bleeding, because blood is
too thin to clot. Too little means they can still be in danger of a
potentially lethal clot.
The
postage stamp-sized patch, developed at North Carolina State
University, keeps a round-the-clock check on thrombin levels and so does
away with the need for repeated blood tests.
On
one side it is covered in more than 100 miniature plastic needles.
These are covered in a coating containing liquid heparin and a special
chemical containing amino acids that binds the drug to the surface of
the needles.
When
thrombin levels are elavated, a chemical reaction takes place within
the amino acid coating — and releases heparin into the blood. So far,
the disposable patch, which can be changed daily, has only been tested
on mice.
Scientists
injected them with large amounts of thrombin — enough to cause a fatal
blood clot — after giving them a patch or a heparin jab.
HIGHER RISK OF BLOOD CLOTS FOR THOSE TAKING TESTOSTERONE PILLS
The
risk of blood clots increases in the first six months after starting
testosterone therapy for erectile dysfunction, according to a report in
the BMJ.
Researchers
studied 19,000 patients who had developed blood clots and found that
compared with men who hadn't used testosterone, current users had a 25
per cent higher risk. Why is unclear, but researchers say men should
discuss it with doctors after starting testosterone treatment.
The
results, published last month in the journal Advanced Materials, showed
all the mice with the patch survived but 80 per cent of those on a
heparin injection died from the results of a clot.
Researchers
said early results suggest the patch is faster and more effective than
injecting the drug, or taking it orally. The team now plan to run
studies testing the patch on patients.
Professor
Martin Cowie, a professor of cardiology at Imperial College London,
says the smart patch could improve anticoagulation for patients at risk
of clots.
'The
concept of a self-regulating patch that tailors the release of a drug
as needed into the body is very innovative. It's well worth pursuing,'
he adds.
Professor
Jeremy Pearson, an associate medical director at the British Heart
Foundation, believes that the patch is 'an ingenious approach'.
'It
may have advantages over current treatment which requires repeated
injections of heparin,' he says. 'The initial results in mice show
promise. It will be interesting to see whether these can be reproduced
in human studies.'
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