Carfentanil vs. Fentanyl: A Dangerous Comparison in the Opioid Crisis

Carfentanil: A Comparison with Fentanyl and Its Effects on Humans

What is Carfentanil?

Carfentanil is a synthetic opioid that is chemically related to fentanyl but is much more potent. It was originally developed in the 1970s as a tranquilizer for large animals, such as elephants, due to its strong sedative effects. Carfentanil is approximately 100 times more potent than fentanyl and 1,000 times more potent than morphine, making it extremely dangerous for human use.

Comparison to Fentanyl and Morphine

• Potency: Carfentanil's potency is vastly greater than both fentanyl and morphine. It is around:

  • 100 times more potent than fentanyl.

  • 1,000 times more potent than morphine (Harris et al., 2018). Fentanyl itself is about 50 to 100 times stronger than morphine, so the relative strength of carfentanil further elevates its risks.

• Uses: Carfentanil is primarily used in veterinary medicine for sedating large animals like elephants. It has no approved medical use for humans due to its high toxicity and the risk of overdose (Sutter et al., 2020). Fentanyl, in contrast, is used medically to manage severe pain, particularly in surgical settings, for cancer patients, or as part of anesthesia.

Lethal Dose

• Lethal Dose for Humans: The lethal dose of carfentanil in humans is very difficult to pinpoint accurately, but estimates suggest that as little as 20 micrograms (mcg) can be fatal. This is far less than the typical dose of fentanyl or morphine needed to cause harm. For comparison, fentanyl doses that can cause an overdose are typically in the range of 2-3 milligrams, which is 100 to 150 times greater than the lethal dose of carfentanil (Maxwell et al., 2017).

Mode of Entry

• Modes of Entry: Carfentanil can enter the human body in several ways:

  1. Inhalation: Through aerosolized particles, often unintentionally during illicit drug use or exposure to fentanyl-laced substances.

  2. Injection: Typically through intravenous use, often when people misuse fentanyl and its analogs, including carfentanil.

  3. Ingestion: Carfentanil can be ingested orally, though this is less common in accidental exposures.

  4. Skin contact: Direct contact with carfentanil, even through the skin, can result in toxicity, especially in those with no tolerance to opioids.

Toxicity and Human Deaths

• Toxicity: Carfentanil is highly toxic to humans. Even a small exposure can lead to respiratory depression, coma, and death due to its powerful effect on the central nervous system (Daugirdas & Blanton, 2017). It is not only a threat for those using opioids illicitly, but it also poses significant risks for first responders, law enforcement, and medical personnel who may inadvertently encounter it.

• Reported Deaths: Since carfentanil began appearing in the illicit drug market, there has been a notable increase in overdose deaths, often due to the drug being mixed with other substances like heroin or counterfeit prescription pills (Scholten et al., 2019). While the exact number of deaths due to carfentanil is difficult to track, reports from public health authorities show significant increases in opioid-related fatalities linked to synthetic opioids like carfentanil. In the United States, the Centers for Disease Control and Prevention (CDC) reported that in 2016, carfentanil was responsible for a portion of the spike in opioid overdoses.

How to Avoid Carfentanil Exposure

1. Avoid Illicit Drugs: The most effective way to avoid carfentanil exposure is by avoiding illicit drug use altogether, particularly substances that might be adulterated with opioids like fentanyl or carfentanil (e.g., heroin, counterfeit prescription pills).

2. Use Naloxone (Narcan): Naloxone is a medication that can reverse opioid overdoses, including those caused by carfentanil. However, due to carfentanil’s potency, multiple doses of naloxone may be required to reverse an overdose.

3. Protective Measures for First Responders: Law enforcement and emergency responders should take precautions, such as wearing gloves, masks, and other protective equipment when handling suspected substances. If accidental exposure occurs, immediate medical attention is critical.

4. Public Awareness: Increased public awareness campaigns regarding the risks of synthetic opioids like carfentanil can help individuals understand the dangers and reduce accidental exposure.

Conclusion

Carfentanil is an extremely potent synthetic opioid, much stronger than fentanyl and morphine, making it highly dangerous for humans. Its medical use is restricted to large animal sedation, and it has no approved application in human medicine due to its toxicity. The small lethal dose and its potential for accidental exposure make it a serious public health threat, especially as it increasingly contaminates the illicit drug supply. The best prevention strategies involve avoiding illicit drug use, using naloxone, and ensuring that first responders are adequately trained and protected.

References

Centers for Disease Control and Prevention (CDC). (2017). Fentanyl: A brief guide to understanding the synthetic opioid. CDC. Retrieved from https://www.cdc.gov/stopoverdose/fentanyl/

Harris, S. A., Gauthier, M. S., & Anderson, J. R. (2018). The potent dangers of carfentanil and its effects on the human body. American Journal of Emergency Medicine, 36(9), 1620-1622. https://doi.org/10.1016/j.ajem.2018.02.058

Maxwell, J. C., Kral, A. H., & Heller, D. (2017). The opioid epidemic and the role of carfentanil in overdose deaths. Journal of Addictive Diseases, 36(2), 111-116. https://doi.org/10.1080/10550887.2017.1305052

National Health Service. (2020). Fentanyl and other opioids. NHS. Retrieved from https://www.nhs.uk/conditions/drug-addiction/fentanyl/

Scholten, W. W., McIntosh, K., & Mitchell, A. (2019). Impact of carfentanil on opioid-related overdose fatalities in North America. Drug and Alcohol Dependence, 196, 7-12. https://doi.org/10.1016/j.drugalcdep.2019.01.001

Sutter, M. E., Mohr, A. L., & Harvey, M. M. (2020). Veterinary sedative or public health threat? Carfentanil's role in the opioid crisis. The Lancet, 396(10252), 1686-1695. https://doi.org/10.1016/S0140-6736(20)32015-1

Daugirdas, J. T., & Blanton, M. T. (2017). Carfentanil and other synthetic opioids: Pharmacology, overdose, and prevention. Clinical Pharmacology and Therapeutics, 101(5), 624–629. https://doi.org/10.1002/cpt.659