Treatment within the first few hours after a stroke is crucial to avoid the most serious outcomes, lead researcher Shaun Jackson from the Heart Research Institute said.

"We are talking about the acute phase of the stroke and there is currently only one drug that is available for the treatment of strokes, a clot dissolving drug called tPA," Professor Jackson said.

However the drug is ineffective for many patients and researchers are working to identify new anti-clotting methods that reduce stroke injury.

"In our preclinical models, we have shown that our anti-clotting drug, when combined with tPA, not only dissolves a blood clot from a stroke more effectively than tPA alone but it can stop the clot from reforming," Prof Jackson said.

"It has the ability to attack different components of the blood clot than tPA alone and the new combination therapy looks very promising in experimental models.

"It does this without an added risk of bleeding, and we know bleeding leads to more strokes so this drug may help reduce risk of another stroke."

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The new drug will be trialled at stroke units at Newcastle's John Hunter Hospital as well as across the country at the Royal Prince Alfred, Prince of Wales, Royal Adelaide and Royal Melbourne Hospital.

"We know from Phase 1 trials in healthy people that this antiplatelet drug is safe and well tolerated," Prof Jackson said.

"We now need to test it to see if it has a positive impact on people who have suffered a stroke."

Patients who suffer an acute ischaemic stroke, the most common form of a stroke where the blood supply to the brain is blocked, will be given the anti-clotting drug in addition to other medications during the first critical hours.