Two deaths in Boulder County, Colorado, in 2023 are the latest in the U.S. to be blamed on the powerful class of synthetic opioids called nitazenes. Most health systems cannot detect nitazenes, so the exact number of overdoses is unknown, but they’re implicated in more than 200 deaths in Europe and North America since 2019, including 11 in Colorado since 2021. One of the two Boulder County deaths is linked to a new formulation called N-Desethyl etonitazene, which was identified by a national laboratory, and is thought to be the first related death. The Conversation interviewed Dr. Christopher Holstege, professor...