New drug offers bigger window to treat stroke

A DRUG which minimises brain damage when given three hours after stroke has proved successful in monkeys and humans.

A lack of oxygen in the brain during a stroke can cause fatal brain damage. There is only one approved treatment - tissue plasminogen activator - but it is most effective when administered within 90 minutes after the onset of stroke. Immediate treatment isn't always available, however, so drugs that can be given at a later time have been sought.

In a series of experiments, Michael Tymianski and colleagues at Toronto Western Hospital in Ontario, Canada, replicated the effects of stroke in macaques before intravenously administering a PSD-95 inhibitor, or a placebo. PSD-95 inhibitors interfere with the process that triggers cell death when the brain is deprived of oxygen.

To test its effectiveness the team used MRI to measure the volume of damaged brain for 30 days following the treatment, and conducted behavioural tests at various intervals within this time.

Monkeys treated with the PSD-95 inhibitor one hour after stroke had 55 per cent less damaged tissue in the brain after 24 hours and 70 per cent less after 30 days, compared with those that took a placebo. These animals also did better in behavioural tests. Importantly, the drug was also effective three hours after stroke (Nature, DOI: 10.1038/nature10841).

From NewScientist