Experimental fentanyl vaccine stops the drug from entering the brain

Even when someone is determined to beat their fentanyl addiction, there's still a good chance they will relapse at some point, and start taking the opioid again. A new vaccine is designed to help get them back on track, by blocking fentanyl's effect on the brain.

Developed by a team led by the University of Houston, the vaccine incorporates a fentanyl-like hapten.

A hapten is a small molecule which, when combined with a larger carrier protein, elicits the production of antibodies which bind to it. In the case of this vaccine, that protein is in fact a genetically deactivated diphtheria toxin known as CRM197 – it is already used in multiple FDA-approved vaccines.

Once the antibodies have been produced, they bind not only to the fentanyl-like hapten molecules, but also to any actual fentanyl molecules present in the bloodstream. Those molecules are thus unable to enter the brain, so they don't produce any feelings of euphoria. They ultimately end up being passed from the body via the kidneys.

Also present in the vaccine is an adjuvant molecule called dmLT, which is derived from E. coli bacteria. Like other adjuvants, it boosts the immune response produced by vaccines, making the medications more effective.

In tests performed on rats, the vaccine was shown to be effective at keeping fentanyl from reaching the brain, while not producing any significant side effects. And importantly, the antibodies which it produces specifically target the fentanyl and hapten molecules, leaving all others alone. This means that other types of opioids, such as morphine, are still effective for pain relief.

Plans call for human clinical trials of the vaccine to begin soon.

"We believe these findings could have a significant impact on a very serious problem plaguing society for years – opioid misuse," said the lead scientist, Assoc. Prof. Colin Haile. "Our vaccine is able to generate anti-fentanyl antibodies that bind to the consumed fentanyl and prevent it from entering the brain […] Thus, the individual will not feel the euphoric effects and can 'get back on the wagon' to sobriety."

A paper on the research – which also involved scientists from Tulane University, the Baylor College of Medicine, and the Veteran’s Affairs Medical Center in Houston – was recently published in the journal Pharmaceutics.

Source: University of Houston