A Vaccine to Treat Cocaine Addiction?
Vaccines to protect against addiction are an exciting yet controversial topic. In a clinical trial supported by the National Institute on Drug Abuse (NIDA), an experimental anti-cocaine vaccine resulted in a substantial reduction in cocaine use in 38 percent of vaccinated patients. The study is the first successful, placebo-controlled demonstration of a vaccine against illicit drug abuse.
"The results of this study represent a promising step toward an effective medical treatment for cocaine addiction," said NIDA Director Dr. Nora Volkow. "Provided that larger follow-up studies confirm its safety and efficacy, this vaccine would offer a valuable new approach to treating cocaine addiction, for which no FDA-approved medication is currently available."
How the Cocaine Addiction Vaccine Works
Similar to vaccines against diseases such as measles and influenza, the anti-cocaine vaccine stimulates the immune system to produce antibodies. Unlike antibodies against infectious diseases, which destroy or deactivate the disease-causing agents, anti-cocaine antibodies attach to cocaine molecules in the blood, preventing them from passing through the blood-brain barrier. By blocking the drug's entry into the brain, the vaccine inhibits or blocks the cocaine-induced euphoria.
Participants in the study were part of a methadone maintenance program (because their retention rates are typically better than programs focused primarily on treatment for cocaine abuse). They were randomly assigned to receive the anti-cocaine vaccine or a placebo. Both study groups received five vaccinations over a 12-week period and were followed for an additional 12 weeks. All participants also took part in weekly relapse-prevention sessions with a substance abuse counselor, had their blood tested for antibodies to cocaine, and had their urine tested three times a week for the presence of opioids and cocaine.
Some of the most important study findings were:
- 38 percent of study participants attained blood levels of anti-cocaine antibodies thought to be sufficient to block cocaine's euphoric effects.
- During weeks 9 to 16 (when antibody levels peaked), these participants had significantly more cocaine-free urine tests than those who received the placebo or those with low levels of anti-cocaine antibodies.
- Participants with the highest antibody levels had the greatest reductions in cocaine use.
- No serious adverse effects were associated with vaccine treatment.
