They have managed to isolate an active ingredient of the poison, tetrodotoxin, without passing on its deadly effects.
The result is 3,000 times stronger than morphine. It can work to ease pain for between eight and 21 days where traditional painkillers are no longer effective.
And unlike morphine, it is non-addictive and has no known side-effects. The poison is found in the internal organs of the puffer, or blowfish, which is regarded as a delicacy in Japan.
Six diners die every year from eating it when it has not been properly prepared.
Just one fish can produce 600 doses of the drug, which attacks the nerve cells that send pain signals to the brain instead of numbing the senses.
Scientists believe it could revolutionise the treatment of pain and allow terminally-ill patients comfort in the final days.
The drug, to be known as Tectin, was developed by Vancouver-based International Wex Technologies after scientists in China noticed the toxin's potential as a painkiller when they used it to help heroin addicts through withdrawal.
Tetrodotoxin is also being tested at Imperial College, London, where research is being carried out into its possible use as a cure for prostate cancer, which kills around 10,000 British men each year.
Wex believes it could soon be available as a painkiller in Canada and the U.S. and, through its partner company Esteve, in Europe.
Attempting to explain the tetrodotoxin effect, Dr Neil Hagen, the principal investigator for the Canadian study, said: "Imagine that you didn't feel it when you were being cut with a knife, but you knew you were being touched
Read more: http://www.dailymail.co.uk/health/article-200851/Health-benefits-deadly-fish.html#ixzz3ma5GgKXt
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