Elephant-tranquilizer (carfentanil)-tainted heroin showing up in Ohio

August 10, 2016, 2:55 pm


Human Health Hazards of Veterinary Medications: Information for Emergency Departments. Lust EB et al. J Emerg Med 2011 Feb;40:198-207


Yesterday, Canadian police announced that, earlier in the summer, they had seized one kilogram of carfentanil contained in a package labelled “Printer Parts” shipped from China and addressed to a man in Calgary.

Carfentanil is frequently, and accurately, referred to as an “elephant tranquilizer.” It is a fentanyl analog, a mu-receptor agonist with a potency 10,000 times that of morphine (or 100 times that of fentanyl.) It is not approved for any medical indication in humans but is used by veterinarians to sedate large animals such as elephants and horses.

The lethal amount of carfentanil is reported to be about 20 μg in humans, which led the police in Canada to claim that the 1 kg seizure contained 50 million deadly doses. It’s unclear if the substance seized was actually pure carfentanil. If it was, that would present an extreme hazmat risk, since the drug is so powerful and can be absorbed after inhalation or through mucus membranes and broken skin.

I had missed this valuable article by Lust et al when it was published in 2011, but came across it when I found it was virtually the only paper available describing the toxicity of carfentanil. The authors note that in animals, the drug has rapid onset and undergoes hepatic metabolism and renal elimination. Manifestations of carfentanil exposure, consistent with opioid toxicity, include mitosis, altered mental status, and respiratory depression. Larger than usual doses of naloxone may be required to reverse the effects of the drug. Areas of mucus membrane or skin exposure should be irrigated abundantly with cool water. (Hot water will increase blood flow to the area and possibly accelerate absorption.)

Other veterinary medications discussed in this article are clenbuterol, ketamine, tilmicosin, testosterone, estradiol, dinoprost,  and cloprostenol.

By the way, recent news about carfentanil has not been limited to the seized shipment in Canada. As the news story from WKRC in Cincinnati at the top of this post reports, carfentanil has been identified in samples and specimens associated with a number of recent overdose cases in the Akron area. Carfentanil-laced heroin has also been associated with at least one fatality in Ohio.

Further reading:

Everything You Should Know About Carfentanil (Vice.com)




  1. DocAmy Says:

    Been associated with more than one fatality. Almost 30 OD deaths in July alone in Akron and most of them are suspected to be due to carfentanil.


    Thanks for posting this. I plan to read this full article.

  2. Leon Gussow Says:


    Wow! Thanks for pointing out this news story. It would be interesting to have forensic information on these cases so we would have data about how many involved carfentanil as a cause or contributing factor.

  3. carfentanil use in humans Says:

    Drug Enforcement Agency has recently captured a packet of one kg Carfentanil drug on airport. DAE has very strict enforcement rules to stop its sale in market other than animals. But legally Carfentanil drug is authorized elephant tranquilizer.