Mice that got four doses of an experimental vaccine over eight weeks kept breathing almost normally after being given fentanyl at levels that would usually cause severe respiratory problems. Scripps Research scientists built the vaccine, and the early results point to protection against fentanyl and several of its chemical relatives.
The problem it targets is familiar. Fentanyl is one of the deadliest drugs in the United States, and tiny amounts can slow or stop a person’s breathing. Naloxone, sold as Narcan, can reverse an overdose, but someone has to give it fast. Many deaths happen because fentanyl was mixed into other illegal drugs without the user knowing, or because new versions appear faster than officials can respond.
The vaccine works in the blood, not the brain. It teaches the immune system to spot the drug, and the antibodies latch on to the molecules and keep them from crossing into the brain.
An unusual design
Kim Janda, a chemistry professor at Scripps and senior author of the study, said the results suggest researchers might stop chasing each new synthetic opioid one by one and deal with the shared problem all at once.
The team did something that cuts against standard thinking. Vaccines against drugs are usually modelled to look like the drug. Here the researchers used a specially designed molecule that shares some traits with fentanyl but has a different core structure. They attached it to a carrier protein and gave it to the mice.
The antibodies picked out fentanyl, carfentanil, acetylfentanyl, furanylfentanyl and China White. They did not attach to morphine or oxycodone. If the vaccine ever reaches human trials, that could let patients keep taking prescribed painkillers when they need them.
Fentanyl levels in the brains of vaccinated mice were about 70 percent lower than in unvaccinated animals. The researchers read that as a sign the antibodies held much of the drug in the bloodstream.
The team said the vaccine is still years from reaching the public. They see it as a possible option someday for people recovering from opioid addiction and those at high risk of accidental exposure to fentanyl.
