(Newser) – Get ready to hear much more about a powerful new street drug called W-18. Police in Edmonton, Canada, this week announced a huge seizure of it made in December—4 kilograms, or enough for hundreds of millions of pills, reports the Globe and Mail. The drug is a synthetic opiate like fentanyl that produces a heroin-like high, but it's 100 times more powerful than fentanyl and 10,000 times more powerful than morphine. As Vice and the CBC explain, it's probably being churned out by labs in China and then shipped to North America via services such as FedEx. This is the second major W-18 seizure within a year in Canada, but it's not just a Canadian problem. A drug dealer in Florida convicted of importing fentanyl also had 2.5 pounds of W-18, the Sun Sentinel reported in March. But because the drug isn't illegal—yet—it didn't factor into his sentence.

"This is the most deadly drug trend I've seen in 31 years," says an epidemiologist at Nova Southeastern University in Florida. Scientists at the University of Alberta developed W-18 in the 1980s as a potential painkiller, though it and other strains in the "W" series, which ran from W-1 to W-32, have since been used mainly for research. The CBC notes W-18 is the most powerful of the 32. No tests are available to detect it in urine or blood, which means it may already be taking an unknown toll on users if it's being cut into other drugs—and perhaps be at least partly responsible for the escalating deaths attributed to heroin. "Often, if the analog is mixed with heroin, heroin just becomes the cause of death," an expert on synthetic drugs in Florida tells the Broward-Palm Beach New Times. (In Ohio, the mother and grandmother of a teen who died after using heroin face charges.)

