Background: A synthetic substance of the benzimidazole structural class, not approved for medical use in the USA. Have been linked to overdoses in several states
Initially developed in 1950’s as analgesic potentially safer than opioids, but were never approved for therapeutic use.
Chemical structure is different from morphine like phenanthrene motif and meperidine analogs like fentanyl
These are the same -azoles that are well known fungicides, used to treat nematode infections etc.
Area also known as ‘nitazenes’ and have street names “iso” and “tony”
Pharmacological profile similar to mu-opioid receptor agonists
Since 2019, DEA has received ~7,000 reports of benzimidazole-opioids in the drug supply, and has been implicated in over 200 drug related overdose deaths in Europe and North America.
800x more potent than morphine, 40x more potent than fentanyl.
Can be injected, smoked, snorted, ingested, and appears in powders, tablets, or liquids
Treatment:
Naloxone is mainstay of treatment: may require 10 mg dose or more.
Supportive care: ABC’s.
Consider co-ingestions: methamphetamine, amphetamine, and benzodiazepine seen in 46.2%, 25% and 13.5%, respectively, of overdoses in Tennessee between 2019-2021.
Harm Reduction:
Give Naloxone prescription – high dose, and multiple RX for those at high risk.
Nitazene test strips are available for purchase at BTNX, but not likely available in the community unlike fentanyl or xylazine test strips
Engage local community stakeholders (EMS, police, other emergency departments, social workers, first responders, community outreach workers, shelters etc) and educate about emerging threat of nitazenes and need for high doses of Narcan as above.
References:
1. BENZIMIDAZOLE–OPIOIDS. Drug Enforcement Administration; 2025. https://www.deadiversion.usdoj.gov/drug_chem_info/benzimidazole-opioids.pdf
2. Roberts A. Notes from the Field: Nitazene-Related Deaths — Tennessee, 2019–2021. MMWR Morb Mortal Wkly Rep. 2022;71. doi:10.15585/mmwr.mm7137a5
3. Pergolizzi Jr J, Raffa R, LeQuang JAK, Breve F, Varrassi G. Old Drugs and New Challenges: A Narrative Review of Nitazenes. Cureus. Published online June 21, 2023. doi:10.7759/cureus.40736
4. Gussow L. What Emergency Practitioners Need to Know About Nitazenes, Potent New Synthetic Opioids. Emergency Medicine News. 2025;47(3):3-3. doi:10.1097/01.EEM.0000000000000010