What’s going on with medetomidine?

Rhino Tranq

How did fentanyl mixed with medetomidine become known as “Rhino Tranq”? The answer is in the etymology of how street drugs are named.

In the pharmacy industry, drug names are assigned according to syllables (stems) in the drug name that convey information about the drug’s chemical structure, action etc. It’s a process wherein multiple names are submitted; one eventually rises to the top and gets submitted to the FDA. The illicit drug market doesn’t work that way. Street drug names are essentially nicknames sharing something in common with the licit drug, such as a chemical similarity or effect.

Xylazine and medetomidine are closely related compounds. Both are nonopioid α₂-adrenergic receptor agonist, veterinary-only drugs. Both are used for sedation, analgesia, and muscle relaxation (common animal tranquilizers). Medetomidine, however, is much stronger than xylazine.

The combination of fentanyl with xylazine is known as “Tranq” on the street. Xylazine is a potent veterinary tranquilizer, but it is not as strong as medetomidine. Think of medetomidine like xylazine on steroids. Xylazine can be used to tranquilize a horse. If you need to tranquilize a larger, more powerful animal (like a rhinoceros), you need a stronger tranquilizer. Hence, the street name “Rhino Tranq” for fentanyl combined with medetomidine.

Questions and answers

Although adulteration of fentanyl occurs with both xylazine and medetomidine, many illicit fentanyl supplies are being identified containing both xylazine and medetomidine. Questions veterinary professionals may have about medetomidine and their answers are as follows:

1. Is medetomidine going to be scheduled at the federal or state level(s)? Medetomidine is not currently scheduled as a controlled substance federally by the DEA, nor have any states scheduled medetomidine at the state level. Legislation is pending in Pennsylvania via PASB866,⁴ which was introduced in July 2025 to add medetomidine as a schedule III controlled substance.
2. Is dexmedetomidine at risk for diversion? Yes, dexmedetomidine is also at risk for diversion and should be securely stored and tracked as a “drug of concern”. The DEA recognizes both medetomidine and dexmedetomidine as threats, with dexmedetomidine typically associated with the diversion of medetomidine.
3. Where is the illicit medetomidine supply coming from? According to the CDC,² the sudden, widespread appearance of medetomidine suggests that the supply is likely entering illicit supply chains multiple ways. In addition to diversion of licit veterinary pharmaceutical-grade product, it is possible that illicit importation of raw medetomidine powder may be entering the United States from foreign countries the same way that xylazine did. Illegal synthesizing of medetomidine may also be occurring in clandestine laboratories because pharmaceutical-grade products mostly contain dexmedetomidine (not medetomidine).
4. Does using medetomidine increase my risk for a surprise DEA inspection? Medetomidine is not federally scheduled as a controlled substance and is not DEA-regulated. However, medetomidine is a known adulterant being used as a cutting agent with fentanyl. Therefore, if you are ordering medetomidine with schedule II controlled substance (particularly fentanyl), you could be more susceptible to an inspection but that is not something that can be verified. The DEA does not publicly release information about how DEA registrants are selected for inspections.
5. Are drug distributors monitoring medetomidine for suspicious ordering? No public statements have been made (or are required to be made) concerning how drug distributors monitor medetomidine among customers. Existing DEA regulations do not indicate how distributors should utilize ordering information related to non-federally scheduled “drugs of concern”. That being said, a lack of scheduling does not prevent distributors from executing due diligence as DEA registrants distributing other drugs and controlled substances; including fentanyl, which medetomidine has become problematic enough as an adulterant with to warrant a joint Health Advisory issued by the CDC and White House ONDCP. All DEA distributors have a duty ensure that orders being placed for medetomidine are reviewed, monitored and responsibly fulfilled per 21 CFR 1301.74(b)⁵.
6. Who do I report suspected or confirmed theft of medetomidine to if the DEA has not scheduled it? Even though as an unscheduled drug medetomidine does not technically fall under controlled substance reporting regulations, as a potent, veterinary sedative that is increasingly diverted for illicit use as a cutting agent with fentanyl, any theft or loss of medetomidine should be reported to the DEA and local authorities. The risk of death from a medetomidine-related overdose may be much higher than the risk with xylazine. From a liability standpoint, if medetomidine is diverted from your facility for illicit purposes and someone dies, the liability is on the veterinarian it was ordered under and the facility it was diverted from. Depending on the ownership structure, that could be one person, multiple people, and/or also include a corporate group. The amount of scrutiny and reputational damage a situation like that generates could result in immeasurable financial losses. Additionally, the court will ask what was done to have prevented the situation as well as if any issues were suspected. If a theft or loss occurred and was not reported, the impact failing to report would have on legal proceedings could be devastating. Remember, DEA registrants must do everything in their power to prevent diversion and protect not only of their inventory but the DEA-registered premises where the inventory is stored.
7. What should I do to manage medetomidine in my practice to protect myself from becoming a target for diversion? If you use medetomidine in the practice of veterinary medicine, taking proactive measures to ensure the safety of your practice, staff, and inventory is a matter of necessity. As an animal-use only drug, veterinary facilities are targets for individuals seeking to divert medetomidine. Medetomidine is a “drug of concern” and should be securely stored and logged for tracking purposes like controlled substances are for monitoring purposes.
8. Can I store and log medetomidine with my controlled substances? No. Medetomidine is a “drug of concern”, not a federally scheduled controlled substance; therefore, it needs to be securely stored and logged separately from controlled substances in accordance with DEA recordkeeping and security requirements.^6-8

Answers to a lot of questions surrounding medetomidine are unclear, while others remain outstanding. It’s important to understand that answers are going to take time. We have an escalating medetomidine problem, a drug for which no regulatory baseline exists. Figuring out the best path forward in terms of oversight and enforcement is complicated given the circumstances. Meanwhile, we are continually playing catchup to illicit drug supply chain operations.

Mitigating Risk

The medetomidine threat is serious, and the risk it poses to the industry is very real. The most important thing to focus on as a veterinary professional right now is mitigating risk by doing everything possible to keep a problem from arising in your facility. If you use medetomidine in the practice of veterinary medicine, I urge you to be proactive and implement security and oversight measures for medetomidine. Proactivity + preparation = prevention.

Kelley Detweiler is a DEA and controlled substance regulatory compliance specialist who provides solutions to veterinarians through her partnership with Dr. Peter Weinstein in Simple Solutions For Vets. She is the DEA compliance CE provider for the American Veterinary Medical Association, the coauthor of Safeguarding Controlled Substances, published by American Animal Hospital Association Press, and the 2024 recipient of the Illinois State Veterinary Medical Association’s President’s Award. She may be emailed at [email protected]

References

1. The White House. Office of National Drug Control Policy, CDC release health advisory on medetomidine in illicit fentanyl. White House. Published April 6, 2026. Accessed April 6, 2026. https://www.whitehouse.gov/briefings-statements/2026/04/office-of-national-drug-control-policy-cdc-release-health-advisory-on-medetomidine-in-illicit-fentanyl/
2. CDC. Medetomidine situation summary. CDC. Published April 2, 2026. Accessed. April 6, 2026. https://www.cdc.gov/overdose-prevention/situation-summary/medetomidine.html
3. Sinclair MD. A review of the physiological effects of α2-agonists related to the clinical use of medetomidine in small animal practice. Can Vet J. 2003;44(11):885–897. Accessed. April 2, 2026. https://pubmed.ncbi.nlm.nih.gov/14664351/
4. PASB866. Bill Track 50 website. Published July 24, 2025. Accessed April 6, 2026. https://www.billtrack50.com/billdetail/1902418
5. 21 CFR 1301.74(b). Code of Federal Regulations website. Published April 24, 1971. Accessed. April 6, 2026. https://www.ecfr.gov/current/title-21/part-1301/section-1301.74#p-1301.74(b)
6. 21 CFR 1301.75. Code of Federal Regulations website. Published April 24, 1971. Accessed. April 6, 2026. https://www.ecfr.gov/current/title-21/chapter-II/part-1301/subject-group-ECFRa7ff8142033a7a2/section-1301.75
7. 21 CFR 1301.72. Code of Federal Regulations website. Published September 21, 1971. Accessed. April 6, 2026. https://www.ecfr.gov/current/title-21/chapter-II/part-1301/subject-group-ECFRa7ff8142033a7a2/section-1301.72
8. 21 CFR 1304. Code of Federal Regulations website. 2009. Published April 6, 2026. Accessed April 6, 2026. https://www.ecfr.gov/current/title-21/chapter-II/part-1304