Fentanyl is a powerful opioid analgesic that initially was brought to the market in the form of transdermal patches, intended for the treatment of severe chronic pain. It is also used in the hospital environment as an injectable drug for anaesthesia and acute pain. Fentanyl is a synthetic drug, based on the morphine molecule, that is 50-100x more potent than morphine on a milligram-to-milligram basis. Fentanyl rapidly penetrates lipids (fat tissues) and once it’s in the bloodstream, quickly reaches the brain and other organs with a short duration of action.
Fentanyl is now infamous because it has entered the illegal drug supply and become a major driver of opiate overdoses and deaths. When used illegally, it is typically supplied as tablets or as a powder. Because so little fentanyl is required for a “high” compared with other drugs, it may be deliberately combined with or sold as other drugs, sometimes with fatal results. Even potentially fatal doses are too small to be tasted or otherwise easily detected.
Fentanyl, like all opioid drugs, works by binding to opioid receptors in the body. In addition to euphoria, it reduces respiration. Overdoses slow breathing, leading to hypoxia, and the accumulation of carbon dioxide. When there is insufficient oxygen to the brain, coma, brain damage, or death can result.
With the recognition that only small doses of fentanyl can be fatal, there have been multiple reports of law enforcement officers that have fallen ill or fainted from simply touching fentanyl. While toxicologists have questioned these stories and pointed out that skin contact is fentanyl is not itself sufficient to cause an overdose, there are multiple stories about “overdoses” attributed to skin contact. (See the Slate article “The Viral Story About the Cop Who Overdosed by Touching Fentanyl Is Nonsense“.) Yes, fentanyl patches do demonstrate that it can be absorbed by the skin, but they work slowly, and are specifically formulated to push the drug across the skin barrier. A specialized transdermal formulation is essential, because skin is normally an effective barrier against a variety of toxins. Transdermal patches, including fentanyl patches, must adhere to the skin and not be removed for some time in order for the drug to diffuse across the membrane and accumulate in the upper layers of the tissue, where it eventually becomes available to the blood stream. Fentanyl is estimated to take 20 minutes just to penetrate the skin and be detectable in the blood. With a fentanyl patch, it will take 1-3 days for steady absorption rates to be achieved.
A case report of inadvertent skin exposure
As a clever pharmacist who found a way to turn an accident into a paper, Ryan Feldman recently wrote up his personal exposure to a very large dose of fentanyl liquid. (Spoilers: He was fine):
Never thought I’d BE a case report, but here we are🤷
Outcomes from confirmed fent exposure are needed to fight misinformation, & sometimes in science accident=opportunity😅
— Ryan Feldman (@EMPoisonPharmD) June 22, 2022
Feldman’s paper describes how he became an unwitting case study. He was disposing of a container of fentanyl solution, but accidentally spilled it on his hand, wrist and forearm. He had a cut and some abrasions on his exposed hand, so the skin was not in optimal condition. One minute after this exposure to approximately 380mcg, he washed the area soap and water. Despite this exposure and skin contact with a very large dose of the drug, a medical exam was normal. He had no signs of opioid exposure and resumed work.
Ultimately, the exposure and absorption of a drug like fentanyl will be based on the area of the body exposed, and the dose that one is exposed to. As the authors point out, this case study should provide reassurance to those concerned about accidental skin exposure.
There is the widespread belief, particularly among first responders, that even brief skin contact with fentanyl can cause overdoses and death. Occupational exposure to opioids is a real concern to this group. Toxicologists have suggested that reported reactions, like fainting, may be psychogenic rather than a result of any actual toxicity. This case study provides more reassurance about ungloved contact with fentanyl. In the event that there is transient skin exposure to fentanyl, no meaningful absorption is anticipated. Simply wash the affected area with soap and water as soon as possible.