A new treatment option for heroin and other opioid misuse diminishes the effects of the drugs, providing new potential to prevent overdoses and help individuals overcome addictions. The experimental vaccine comes from scientists at the The U.S. Military HIV Research Program (MHRP) at the Walter Reed Army Institute of Research (WRAIR).
The vaccine works by activating antibodies that prevent misused opioids from crossing the blood-brain barrier (BBB), a diffusion barrier that protects the brain from being exposed to things like drugs in the blood. In addition to heroin, misuse of opioids like hydrocodone, oxycodone, and codeine are contributing to a growing opioid epidemic in the United States, as the Centers for Disease Control and Prevention estimates that 91 Americans die every day of an opioid overdose.
Researchers tested the experimental vaccine in rats and mice, in their new study published in the Journal of Medicinal Chemistry. It contains drugs that stimulate the immune system, an adjuvant called the “Army Liposome Formulation” (ALF).
“The vaccine aims to block the euphoria and addictive effects,” explained MHRP’s Dr. Gary Matyas. “This study suggests that vaccination can be used together with standard therapies to prevent the withdrawal and craving symptoms associated with opioid withdrawal."
Before Matyas and others could confirm the vaccine’s potential to be used with other therapies, they had to ensure that the antibodies activated by the vaccine would not cross-react with other drugs used for opioid misuse, including methadone, buprenorphine, and naltrexone. They found that antibodies induced by the new experimental vaccine do not react with these drugs or with a drug called naloxone, which is used as an “overdose rescue” treatment.
Overdose rescue treatment reverses the effects of hypoventilation, or respiratory depression. Hypoventilation is characterized by slow and ineffective breathing caused by the body’s inability to effectively remove carbon dioxide to make room for oxygen; hypoventilation can lead to confusion, headache, and seizures.
The new study also found that the vaccine has no reaction with non-narcotic pain relievers, including aspirin, ibuprofen and acetaminophen.
Researchers involved with the study are hopeful that further studies of the experimental opioid vaccine will eventually improve access to and success of treatment for opioid management therapy, which is often not available and is associated with high relapse rates even when it is accessible.