A vaccine that blocks fentanyl from entering the brain in rats — and thus prevents severe addiction — could one day be used to treat opioid addiction.
Importantly, the vaccine did not block the effects of other opioids, other than fentanyl, meaning they may not block pain in humans using other methods.
“We believe these findings could have a significant impact on a major problem that has plagued society for decades – opioid abuse,” says Colin Haile, a neuroscientist at the University of Houston, lead author of the study.
In this study, researchers gave rats three doses of a fentanyl vaccine over a three-week period. Another group of rats received a placebo.
The researchers took regular blood samples, showing the increase in anti-fentanyl antibody over time in the vaccinated rats.
After the vaccination schedule, the rats were given a dose of fentanyl.
To see if the vaccine blocks fentanyl’s pain-killing effect, the researchers measured the pain responses of the vaccinated rats by heating the rats’ tails for less than 10 seconds and seeing how long it took them to go away.
In another study, they exposed the rats to a hotplate and timed the time it took them to lick their hind legs.
Mice that were given the vaccine got rid of pain faster than the control group in both experiments, showing that the vaccine – when given at a higher dose of two – was blocking the pain of fentanyl.
A post-mortem examination showed that the vaccine reduced the amount of fentanyl in the brain.
“Our vaccine can create anti-fentanyl antibodies that bind to ingested fentanyl and prevent it from entering the brain, allowing it to be excreted through the kidneys,” says Haile.
Researchers they didn’t see any side effects in the vaccinated rats involved in the lab studies, but of course, more work is needed before the vaccine goes to clinical trials.
The researchers are now planning human trials.
They expect to see fewer side effects because fentanyl vaccines are often made with components already approved for use in human vaccines: a small molecule like fentanyl linked to a large protein carrier called CRM197, which has been approved for use. human vaccine, is a helpful molecule called dmLT that enhances the immune system and has been proven safe in many clinical trials.
Together, these components stimulate the immune system to recognize fentanyl as a threat and create antibodies that prevent the drug from reaching the brain, similar to how a cold shot teaches the immune system to recognize its target.
The synthetic opioid fentanyl is 100 times more potent than morphine. Many doctors have been prescribing them for pain relief since the 1990s, leading to the ‘opioid epidemic’ in the United States, where more than 150 people die from fentanyl overdoses every day.
It only takes about two milligrams of fentanyl to kill someone. Drugs such as heroin are often mixed with fentanyl to give them an extra boost – a problem that has prompted police to issue warnings about the deadly drug circulating on the black market.
Studies show that nearly 90 percent of people who seek opioid addiction treatment relapse due to addiction.
Naloxone can be used in an emergency to prevent death from fentanyl overdose, and daily drugs such as methadone can reduce appetite and withdrawal, prevent overdose death, and help people not to take fentanyl – but it all depends on people who follow the treatment.
However, a vaccine that works longer to block the effects of fentanyl could help people overcome addiction more quickly, potentially reducing fentanyl-related deaths.
This study was published in Medicine.
