Low Dose of Controversial Stroke Drug, rtPA Could Save Lives

Intravenous rtPA (or alteplase) works by breaking up clots blocking the flow of blood to the brain and is given to people suffering acute ischaemic stroke within the first few hours after the onset of symptoms.

Traditionally administered at a dose of 0.9mg/kg body weight, rtPA can go one of two ways: it can either save a person’s life and prevent disability resulting from a stroke, or cause a brain bleed and death in five per cent of all cases.

But now researchers believe they have come up with a compromise. A study released today, involving over 3,000 patients in 100 hospitals worldwide, finds that a lower dose of 0.6mg/kg could prevent deaths from strokes and reduce rates of serious bleeding in the brain, intracerebral haemorrhage (ICH), by two thirds.

“At the moment you could have a stroke but end up dying from a bleed in the brain,” says study lead author and senior director of the Neurological and Mental Health Division at The George Institute for Global Health, Professor Craig Anderson.

“It’s largely unpredictable as to who will respond and who is at risk with rtPA.

“What we have shown is that if we reduce the dose level, we maintain most of the clot-busting benefits of the higher dose but with significantly less major bleeds and improved survival rates.

“On a global scale, this approach could save the lives of many tens of thousands of people.”

The Stroke Foundation says 26 per cent of ischemic stroke patients in Australia receive disability reducing thrombolysis treatment within 60 minutes of hospital arrival.

Maurice Wilson, 57, had a stroke and was administered the standard, higher dose of rtPA at Sydney’s Royal Prince Alfred Hospital under a month ago.
“tPA, or thrombolysis, is currently recommended as a leading treatment for ischaemic stroke in Australia and around the world,” says A/Prof Campbell.

“It is crucial that tPA is administered in stroke units, and emergency departments with appropriate expertise and infrastructure for monitoring, rapid assessment and investigation of patients with acute stroke.”

However, the Stroke Foundation is currently reviewing the stroke clinical guidelines, including the use of tPA.

The Australasian College of Emergency Medicine’s clinical care advice on stroke does not endorse use of IV rtPA and says it is applicable only to a minority of stroke patients, and should be seen as a treatment option indicated in carefully selected stroke patients, rather than a standard of care.

Although the study, published in the New England Journal of Medicine, found that the lower dose of rtPA reduced resulting deaths, it did not reduce the amount of people suffering a residual disability from a stroke.

The study’s authors and the Stroke Foundation say more research is needed to confirm the low dose as a treatment for use.

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