Questions are being raised about claims that Canada’s newest illicit street drug is 100 times more toxic than the powerful opioid fentanyl. The Canadian inventor of W-18 says people are jumping to conclusions that aren’t supported by the scientific literature. Ed Knaus says the drug may not even be an opioid, because its mechanism of action on the body hasn’t been proven. W-18 was patented as a pain reliever in the early 80s, and made illegal earlier this month after police found it turning up on the illicit drug market. Doctor David Juurlink is the head of pharmacology at Toronto’s Sunnybrook Health Sciences. He says W-18 may be dangerous, but more research is needed before conclusions can be drawn about its potency. He says the main thing about the synthetic drug is that “we don’t know very much.”