Deaths from opioid drug overdoses are surging in the U.S., with a recent report by the Centers for Disease Control and Prevention (CDC) suggesting that the number of fatalities has now reached “epidemic” levels. Fortunately, help may soon be at hand, thanks to researchers from The Scripps Research Institute who have developed a vaccine that could give users immunity to the effects of some of the most powerful opioids.
Opioids are natural or synthetic compounds that bind to the opiate receptors in the brain and central nervous system in order to numb feelings of pain. They are found in many prescription painkillers such as morphine and oxycodone, as well as street drugs like heroin. While the recent rise in opioid deaths has been attributed to the use of both pharmaceutical and illegal drugs, one particular opioid, called fentanyl, has been identified as among the most dangerous.
Thought to be at least 10 times stronger than heroin and 80 times more powerful than morphine, fentanyl is a synthetic opioid prescribed to patients suffering from severe pain that cannot be dampened by weaker drugs. Because fentanyl is easily synthesized, several of its derivatives have become common street drugs, under names such as China White, Apache, and TNT.
Given the compound’s potency, misuse of these drugs carries a high risk of overdose, which can provoke respiratory depression and other potentially fatal effects. It’s therefore hardly surprising that the rise of China White as a popular narcotic in the late 1980s produced a spike in opioid-related deaths in the eastern U.S. More recently, a new designer variation called acetylfentanyl has been linked with a string of overdose deaths.
Many prescription painkillers and street drugs contain opioids. David Smart/Shutterstock
To create the vaccine, scientists used a compound with the same “core scaffold” as fentanyl, which was then attached to a carrier protein and administered to mice. After delivering the vaccine, the researchers analyzed subjects’ blood plasma and found an increase in antibodies with a specificity for fentanyl type drugs. Since antibodies help to eliminate specific foreign invaders, this essentially recruited the mice’s own immune system to destroy the drug once it entered the bloodstream, thereby preventing it from reaching the brain.
Publishing their findings in the journal Angewandte Chemie, the study authors explain how they administered a number of different fentanyl derivatives to vaccinated mice, and found that the effect of these drugs were either eliminated or greatly reduced. For example, to test the painkilling properties of these compounds, researchers placed the mice on a hot surface and measured the level of heat they were able to withstand. After receiving the vaccine, mice needed 30 times more fentanyl than their non-vaccinated counterparts in order to generate an increased ability to endure pain.
Furthermore, a dose of fentanyl that proved fatal to 55 percent of non-treated mice was safely tolerated by all vaccinated mice, indicating that the vaccine may indeed help to prevent opioid-related overdose deaths. These effects were maintained in subsequent tests performed six weeks after delivering the vaccine, but began to wane after around 10 weeks. As such, the vaccine appears to have successfully stimulated the rodents’ immune system to continue to produce the relevant antibodies for some time after administration, but may require booster shots in order to consolidate this effect.
The researchers also think it might be possible to make even more powerful vaccines, maybe even those that are effective against both fentanyl and heroin, a desirable double attack given that the latter is often mixed with fentanyl derivatives.