It was never tested on humans but is now being manufactured and sold by clandestine labs in Asia. "These synthetic opioids are so potent you essentially have to dilute it by mixing it in with heroin or something else because it's too powerful," he said. Thirty-one states have reported overdose deaths from U-47700. That includes Colorado, where two people were killed in Boulder County in January. But it was a case in Utah that thrust the drug into the national spotlight. Two 13-year-olds overdosed and died after buying the drug from a classmate who purchased it online. Hospitals are also...