Japanese drugmaker Eisai Co Ltd, which acquired European rights to Prialt from Ireland's Elan Corp Plc, is marketing the medicine first in Britain before rolling it out in other European markets.
The drug is the synthetic equivalent of a substance produced by the predatory cone snail Conus magus, found off the Philippines, which uses it in a venomous "harpoon" to paralyze fish.
In humans, it shuts down pain pathways by stopping nerve cells from sending signals to the brain.
The drug is extremely potent and can cause side effects including dizziness, nausea and blurred vision.
It is only designed for a small group of patients with cancer and other serious conditions linked to severe pain and is delivered through a tiny pump directly into fluid surrounding the spinal cord.
Eisai agreed in February to pay Elan up to $100 million for European rights to Prialt, which industry analysts expect to be a niche product with modest sales.
In the United States, where Elan kept rights, the drug sold $6.3 million in 2005 after being launched in the first quarter.
Prialt will cost 271.83 pounds ($499.7) in Britain for a vial containing 100 micrograms. The average final dose used in studies testing the drug was 7.2 micrograms per patient a day.
"Source":[ http://today.reuters.co.uk/news/newsArticle.aspx?type=scienceNews&storyID=2006-07-09T233219Z_01_L07891191_RTRIDST_0_SCIENCE-HEATH-EISAI-PRIALT-DC.XML&archived=False]