Last Updated: Friday - 09/24/2010
Week of October 11, 2004
Puffer fish's toxin may ease cancer's crippling pain
By BILL GLEN
WCR Staff Writer
A deadly toxin derived from an unlikely source may help ease the horrible pain associated with cancer since it was first developed and tested for heroin withdrawal.
Tetrodotoxin, a lethal poison found in puffer fish, has been patented by a Vancouver-based company and is the subject of clinical trials across Canada after an initial study revealed 72 per cent of patients experienced significant pain relief.
Wex Technologies manufactures the toxin derivative under the names Tetrodin and Tectin.
Dr. Doreen Oneschuk, a physician on the palliative care unit at Edmonton's Grey Nuns Hospital, participated in a study two years ago targeting 10 patients across Canada. She and other investigators are seeking suitable patients for the next study.
Tetrodin is not a cure for cancer. It is a drug designed to relieve pain.
The new study is double-blind and placebo-controlled, meaning the doctors and patients do not know whether they are receiving the medication. Fifty per cent of the patients will receive Tetrodin while the other half will be given a pain-suppressing placebo. This differs from the past study where all of the patients received Tetrodin.
"The prior study was to test safety and ethicacy. This is now taking it one further step. It is customary to progress along this line."
Wex says the next trial phase will occur in up to 25 treatment centres and involve more than 100 people. So far, Oneschuk has not found anyone to participate.
"We are hopeful. It is exciting because this is something unique. We are going back to the availability of a fish no one could ever think of having tremendous potential to help people in pain. And we are looking at patients who might need only a limited number of dosings; they would not be required to take medication on a prolonged basis."
Oneschuk is hesitant to say if this form of treatment might reduce the number of patients who might be inclined to seek euthanasia, given that several factors can affect when a person might want to end his life.
"The request for euthanasia is not solely based on controlled physical symptoms," she said. "It often extends to issues dealing with psycho-social, existential and spiritual distress and dignity. It is very complex. You can't exclusively consider this to be the panacea."
Side effects from using the drug can include numbness and tingling in the lips and limbs.
There are monthly teleconferences involving 25 investigators who are actively recruiting patients who must satisfy strict admission criteria. For example, a patient must have a poor response to more traditional pain treatment and there must not be any other medication that could contribute to a significant complication that may overlap with the effects of Tetrodin.
"How this is also differing from the prior study is that we were looking at severe pain. It has been reduced to moderate or severe pain. I think the hope is to open up to others but for now, this study is still cancer patients," she said.
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