By Pat Anson, Editor
Scientists at The Scripps Research Institute have developed an experimental vaccine that appears to significantly lower the risk of an overdose from prescription opioids and could someday revolutionize opioid addiction treatment. The vaccine also blocks the pain-relieving effects of opioid medication.
“We saw both blunting of the drug’s effects and, remarkably, prevention of drug lethality,” said co-author Kim Janda, PhD, a professor of chemistry at Scripps. “The protection against overdose death was unforeseen but clearly of enormous potential clinical benefit.”
Vaccines typically take advantage of the immune system’s ability to recognize and neutralize foreign invaders such as bacteria.
When injected, the opioid vaccine triggers an immune system response when two widely used painkillers -- hydrocodone and oxycodone -- are detected. Antibodies released by the immune system seek out the opioids and bind to the drugs' molecules, preventing them from reaching the brain.
“The vaccine approach stops the drug before it even gets to the brain,” said study co-author Cody Wenthur, PhD, a research associate at Scripps. “It’s like a preemptive strike.”
In tests on laboratory mice, scientists found that the opioid vaccine blocked the pain relieving effects of oxycodone and hydrocodone, as well as any euphoria. The vaccinated mice also appeared less susceptible to a fatal overdose.
“Our goal was to create a vaccine that mirrored the drug’s natural structure. Clearly this tactic provided a broadly useful opioid deterrent,” said study first author Atsushi Kimishima, a research associate at Scripps.
Currently, opioid addiction treatment relies on other opioids – such as methadone and buprenorphine (Suboxone) – to stifle cravings for opioids. But those drugs can be abused as well.
Although some of the vaccinated mice succumbed to an opioid overdose, researchers found that that it took much longer for the drug to impart its toxicity. If this effect holds true in humans, the opioid vaccine could extend the window of time for emergency treatment if an overdose occurs.
The next step for researchers is to refine the dose and injection schedule for the opioid vaccine. It may also be possible to make the vaccine more effective. Scripps researchers are already working on vaccines to block the effects of heroin, fentanyl and other synthetic opioids.
The Scripps study has been published in the journal ACS Chemical Biology. The study was supported by the National Institute on Drug Abuse of the National Institutes of Health.
California-based Opiant Pharmaceuticals is developing a similar vaccine designed to treat heroin addiction. The company recently announced that it has obtained exclusive development and commercialization rights to an experimental heroin vaccine invented by scientists at the Walter Reed Army Institute of Research and the National Institute on Drug Abuse.
“Aggressively addressing heroin addiction is part of Opiant’s mission,” Roger Crystal, MD, CEO of Opiant said in a news release. “In our view, this vaccine fits our plan to develop innovative treatments for this condition. The vaccine has promising preclinical data.”
Opiant’s first commercial product was Narcan, an emergency nasal spray that rapidly reverses the effects of an opioid overdose.
“Whilst our development of Narcan Nasal Spray to reverse opioid overdose has been a significant effort to address the unfortunate consequences of heroin addiction, we see the vaccine as having potential in addressing the disease itself,” said Crystal.