London, UK (BBN)-A panel of independent experts has decided that a clot-busting drug often used to treat strokes is "safe and effective".
The UK medicines watchdog wanted the benefits and risks of alteplase to be analysed after concerns were raised about its safety, reports BBC.
The panel concluded that the best time to use the drug is up to four and a half hours after the start of symptoms.
But some other doctors are still not convinced by the evidence.
Most strokes are caused by a clot blocking the flow of blood to the brain.
Many patients are given the drug alteplase to break down and disperse the clot - a treatment known as thrombolysis.
BENEFITS OUTWEIGH RISKS
The independent expert panel, chaired by Prof Sir Ian Weller, said it had looked at all available data on alteplase and decided that the earlier the drug was given to patients, the greater the chance of a good outcome.
Used up to four and a half hours after the onset of symptoms, the benefits of the drug were found to outweigh the risks.
But it added that the benefits of using alteplase to treat strokes were "highly time-dependent" and, in a small number of people, there was a risk of haemorrhage.
Prof Weller explained: "The evidence shows that for every 100 patients treated with alteplase, whilst there is an early risk of a fatal bleed in two patients, after three to six months, around 10 more in every 100 are disability-free when treated within three hours."
Five more patients in every 100 are left with no disabilities when treated between three and four-and-a-half hours after a stroke, he said.
However, there are still medical experts who have concerns.
'WORRIED'
Sir Richard Thompson, past president of the Royal College of Physicians, who sat in on proceedings as an observer, said he felt no progress had been made.
"An investigation like this should look at the evidence from both sides like a court of law. I didn't get the feeling there was a real examination of the evidence. Most of it came from people working in the field."
Dr Roger Shinton, a stroke expert, said there was more to find out.
"I'm sure there will be some further information, which we will all find helpful and that is to be welcomed.
"But I'm worried that most of the key bits of information that will help resolve this debate are still not going to be available."
Dr June Raine, the director of vigilance and risk management of medicines at the MHRA - the UK's medicines watchdog - said a thorough scientific assessment had been carried out, using all the latest evidence.
She added: "We will continue to monitor the safety of alteplase and if any new evidence emerges we will reassess the benefit-risk balance."
Dr Dale Webb, director of research and information at the Stroke Association, said the findings of the review were "extremely welcome news for stroke patients and their families".
"Eligible patients treated with thrombolysis [using alteplase] are more likely to lead more independent lives.
"However, this type of treatment is not suitable for everyone struck down by stroke."
The Stroke Association says it is funding research into other ways to help improve recovery rates from the condition.
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