NIH Study Finds Experimental Nitazene‑Derived Opioid Reduces Pain in Mice Without Addiction Signs

A National Institute on Drug Abuse team reports that an experimental drug called DFNZ, derived from the highly potent and illicit nitazene class of synthetic opioids, produced strong pain relief in mice without the hallmark risks of standard opioids, including respiratory depression, tolerance and physical dependence, at preclinical therapeutic doses. In early animal tests, DFNZ reached the brain within five to 10 minutes and provided at least two hours of analgesia while actually increasing brain oxygen levels instead of suppressing breathing. The researchers, led by NIDA investigator Michael Michaelides, say repeated dosing did not trigger meaningful withdrawal symptoms aside from irritability and suggest DFNZ might eventually serve both as a safer pain medication and as a treatment for opioid use disorder, although it has not yet been tested in humans. NIDA director Nora Volkow called the prospect of an effective pain drug without addiction and overdose risk an enormous potential public‑health benefit, but outside experts stress that nitazenes as a class are currently a deadly black‑market threat and that any spin‑off compound will require rigorous clinical trials. The work lands amid a still‑raging U.S. opioid and fentanyl crisis, and is already driving online debate over whether decades‑old chemical families like nitazenes can be repurposed into tools rather than just hazards in the drug epidemic.