Thrombolytic therapy with the drug alteplase can help some patients lead more independent lives following a stroke, even when the drug is given more than 3 hours after symptoms begin.
Researchers reported in the October 17 Lancet on 800 patients who were randomly assigned to receive alteplase or placebo. Most were treated from 3 to 6 hours after symptoms appeared. Alteplase is a recombinant tissue-type plasminogen activator that previous studies found to be effective in limiting brain injury from stroke if it is given within 3 hours of the onset of symptoms. The problem is that most patients don't seek treatment in time to benefit from the drug.
Voelker R. Improving Stroke Outcomes. JAMA. 1998;280(18):1559. doi:10.1001/jama.280.18.1559-JWM80008-3-1