A tiny Canadian company wants to use poison from a fish ? a substance more toxic than cyanide ? to help cancer patients suppress pain or to wean heroin addicts off their habit. International Wex Technologies, a Vancouver-based company listed on the small-cap Canadian Venture Exchange, says early trials show positive results from tetrodotoxin, although bigger and more extensive tests will be needed before the product reaches the marketing stage. It says the new drug could be on the market within three years, if all the tests work out.

The new drug is derived from a blowfish poison ? a substance so dangerous that a mere trace can paralyse a person within minutes. The blowfish is known to gourmets as the source of the sometimes deadly Japanese fugu delicacy, a dish that can be prepared only by trained and licensed chefs, because the slip of a knife can poison the food, causing the diner to drop to the ground convulsing and gasping for air. It has been described as the culinary version of Russian roulette.

But the drug derived from the poison, tetrodotoxin, has already passed two phases of clinical tests, and doctors conducting early surveys say it eased pain in terminally ill cancer patients, where no other pain medication had worked. Dr Edward Sellers, a professor of pharmacology at the University of Toronto helped Wex conduct its Phase II trials, a study of 22 patients.

Sellers said one patient in his mid-50s was in such agony that he couldn?t even wear his clothes without sharp surges of pain. But with shots of Tectin, Wex?s patented name for tetrodotoxin, his pain subsided for more than week.

Researchers injected patients with several micrograms of Tectin ? a quantity so small it can?t be seen with the naked eye ? twice a day for four days, and found that nearly 70 percent experienced a reduction in pain. Pain relief began around the third day of treatment, and often lasted after the final injection. In some cases, the relief extended beyond 15 days, the study showed. Tectin, a sodium channel blocker, stops nerves from sending pain signals to the brain.

The company says Tectin differs from other painkillers in that it doesn?t have the same side effects as morphine and its derivatives, doesn?t interact with other medicines and is not addictive. It is up to 3,200 times stronger than morphine. The success of the early Tectin tests is a small coup for a company that has set its sights on the $38 billion North American painkiller market, some 10 percent of which comes from managing cancer pain.