Wearable Patch Could Automatically Reverse a Fentanyl Overdose

Researchers at Virginia Tech's Department of Biological Systems Engineering have built a wearable patch, smaller than a penny, that can detect fentanyl in the body and automatically release naloxone, the medication that reverses opioid overdoses. Called the iNal patch, it is designed to help even when no other person is nearby to administer the antidote. The work, led by assistant professor Wujin Sun, was published in the journal Advanced Science.

The patch contains an array of 121 microscopic needles that reach fluid just below the skin without causing significant tissue damage. Embedded in it are porous silica nanoparticles filled with naloxone, sealed behind molecular gates that respond to fentanyl. When fentanyl reaches the patch, the gates open and release naloxone, with more released as fentanyl levels rise. Only some pores open each time, leaving naloxone in reserve in case fentanyl exposure happens again.

In laboratory tests, the patch began responding within minutes and kept releasing naloxone for as long as 24 hours. In tests on mice, higher fentanyl doses triggered larger naloxone releases, and the device remained responsive through at least three separate exposures. Mice wearing the patch developed substantially fewer signs of opioid overdose than mice exposed to fentanyl without it. The researchers reported no significant irritation or other harmful effects from the patch in these tests.

Sun described the device as a harm-reduction tool rather than a replacement for pain medication, intended to catch cases where someone taking opioids for legitimate pain relief has an accidental overdose. The researchers, who have filed a patent application, said more testing is needed to determine how durable the patch is over time and how it performs on different skin types before it can be used in people.