It's a drug that Hakique Virani describes simply as "terrifying."

Virani is talking about W18, a man-made opioid like fentanyl. Except, in one key respect.

Its potency.

Edmonton police seized four kilograms of powdered W18 in December, and Virani did the math.

"In fact, the quantities that I'm hearing of would kill every person in Alberta where we found W18 dozens of times over," he said in an interview.

Virani is a public health physician who also teaches at the Faculty of Medicine at the University of Alberta.

Fentanyl is often described as 100 times more potent than morphine. W18 is 100 times more potent than fentanyl.

Police and health officials in Saskatchewan are well aware of fentanyl. The illicitly-produced drug is responsible for dozens of overdose deaths in this province since 2010, largely because there is no quality control in pills made illegally.

Saskatoon Police say they've heard of the new drug, but are not aware of any in the city.

Part of the difficulty with W18 is that it's very difficult to detect in toxicology tests because such minute amounts are needed for an overdose.

And the reality with the drug trade is that substances that are on the street in B.C. and Alberta typically work their way here.

Virani said the arrival W18 drives home the point that Canada needs updated guidelines on opiate prescribing.

This could mean better physician education and giving regulatory authorities the power to address harmful prescribing.