W-18 data about potency, classification lacking: Health Canada

Health Canada has taken a step back from claims that W-18 is a synthetic opioid that is 100 times more powerful than fentanyl, now acknowledging more research is needed.

More research needed on chemical drug showing up on Canadian streets, say officials

This picture, purported to show a powder sample of W-18, appears on a website based in China that promises to ship it. The caption reads, 'Not for human consumption.' (Smallorder)

Health Canada has taken a step back from claims that W-18 is a synthetic opioid that is 100 times more powerful than fentanyl, now acknowledging more research is needed.

The department issued a statement Tuesday clarifying its position on the drug after experts questioned widely circulated assertions about its potency and classification.

Health Canada said it referred to W-18 as a synthetic opioid to align with multiple sources, including the European Monitoring Centre for Drugs and Drug Abuse, and because the limited scientific information available compared it to morphine.

However, doubts about this classification have been raised recently by a number of "credible sources," the department said.

"It has been noted that, at present, while the only publicly available scientific report compares W-18 and related compounds to opioids, it does not determine whether or not W-18 binds to opioid receptors in the body," it said.

"The department is aware of ongoing studies to determine the mode of action of W-18 and will continue to assess new information as it becomes available."

Created in Edmonton

W-18 is a chemical created at the University of Alberta between 1977 and 1979 as part of a drug-design project aimed at creating a compound for pain relief. It was never produced commercially and the series was eventually shelved.

Police and health officials have issued several warnings about the drug, which they say is extremely dangerous.

Canada recently made it illegal to produce, possess, import, export or traffic W-18 after the substance was identified during several drug seizures. In a June 1 news release, Health Canada said W-18 "can be 100 times stronger than fentanyl."

But the inventor of W-18, Ed Knaus, has pointed out that he and other researchers who developed the drug never compared its potency to fentanyl.

Health Canada said on Tuesday that the only publicly available report on W-18 is the 1984 patent application, which included a study that used mice to test the pain-relieving activity of the compound. The results were compared to several other drugs, including aspirin and morphine.

The research found it takes 10,000 times more morphine than W-18 to produce the same analgesic effect in mice.

Fentanyl is 100 times stronger than morphine. Therefore, if the research results are interpreted to mean W-18 is 10,000 times stronger than morphine, that would make the drug 100 times stronger than fentanyl.

More research underway

However, Bryan Roth, a pharmacologist at the University of North Carolina, has said the study results don't necessarily mean W-18 is 10,000 times more dangerous than morphine. He is conducting his own research on W-18.

On Tuesday, Health Canada noted the limitations of the research but said the available data suggests a "potentially severe risk for harm to individuals."

Dr. David Juurlink, head of the division of clinical pharmacology and toxicology at Sunnybrook Health Sciences Centre, said recently that while W-18 could very well be dangerous more research is needed before conclusions can be drawn about its chemical behaviour and potency. (Michelle Siu/Canadian Press)

"In addition, the lack of data ... could lead users to rely on self-reported experiences and other information from user web forums, which may be inaccurate."

Health Canada emphasized that it is not currently known whether overdose-reversing agent naloxone would be effective for someone who had taken W-18.

However, administering naloxone would not hurt the person, and 911 should also be called for emergency medical assistance, it said.