Pharmacists May Someday Give Cocaine Shot

Vaccines have long been used to fight diseases, but a new, experimental vaccine is the first of its kind that has shown efficacy in fighting the disease of cocaine addiction. The results of a clinical trial supported by the National Institute on Drug Abuse (NIDA), part of the National Institutes of Health, showed a significant decrease of cocaine use in 38% of vaccinated patients.

"The results of this study represent a promising step toward an effective medical treatment for cocaine addiction," said NIDA Director Nora Volkow, MD. "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."

The vaccine stimulates the immune system to produce antibodies, which attach themselves to cocaine molecules in the blood and stop them from passing through the blood-brain barrier. The typical cocaine-induced euphoria is thereby blocked, as the drug's entry into the brain is prevented.

For the study, 115 patients from a methadone maintenance program were randomized to receive either the anti-cocaine vaccine or a placebo. All participants received 5 vaccinations over the course of 12 weeks and were followed for the subsequent 12 weeks. In addition, all patients enrolled in the study had their blood tested for antibodies to cocaine and their urine tested 3 times a week for opioids and cocaine, as well as took part in weekly relapse-prevention therapy sessions with a substance abuse counselor.

Antibody levels peaked between weeks 9 and 16, with the 38% of patients who showed a significant reduction in cocaine use seeing the highest levels. Study participants generated varied levels of antibodies in response to the vaccination.

"Fifty-three percent of participants in the high-antibody group were abstinent from cocaine more than half the time during weeks 8 to 20, compared with only 23% of participants with lower levels of antibodies," said Thomas Kosten, MD, of Baylor College of Medicine in Houston, Texas, the study's lead investigator. "In this study, immunization did not achieve complete abstinence from cocaine use. Previous research has shown, however, that a reduction in use is associated with a significant improvement in cocaine abusers' social functioning, and thus, is therapeutically meaningful.

The study was published in the October issue of the Archives of General Psychiatry.

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