Cocaine Vaccine Shows Promise for Treating Addiction

| by National Institutes of Health

Immunization with an experimental anti-cocaine vaccine resulted
in a substantial reduction in cocaine use in 38 percent of vaccinated
patients in a clinical trial supported by the National Institute
on Drug Abuse (NIDA), a component of the National Institutes of
Health. The study, published in the October issue of the Archives
of General Psychiatry, is the first successful, placebo-controlled
demonstration of a vaccine against an illicit drug of 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."

Like vaccines against infectious 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 themselves to cocaine molecules in the blood,
preventing them from passing through the blood-brain barrier. By
preventing the drug’s entry into the brain, the vaccine inhibits or
blocks the cocaine-induced euphoria.

This study included 115 patients from a methadone maintenance
program who were randomly assigned to receive the anti-cocaine vaccine
or a placebo (inactive) vaccine. Participants were recruited from a
methadone maintenance program because their retention rates are
substantially better than programs focused primarily on treatment for
cocaine abuse. Participants in both 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 therapy
sessions with a trained 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.

Participants differed in the levels of antibodies generated in response to
vaccination. Thirty-eight percent 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 urines than those who received the placebo or those with
active vaccine but 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.

"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 percent of participants with lower levels of
antibodies," said Thomas Kosten, M.D., of Baylor College of Medicine in
Houston, the study's principal investigator.

"In this study immunization did not achieve complete abstinence from
cocaine use," added Dr. Kosten. "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

Dr. Kosten led the study in collaboration with colleagues from Yale
University School of Medicine, the Connecticut Veterans Administration
(VA) Healthcare System, Baylor College of Medicine, and the Michael E.
DeBakey VA Medical Center.

The National Institute on Drug Abuse is a component of the National
Institutes of Health, U.S. Department of Health and Human Services.
NIDA supports most of the world's research on the health aspects of
drug abuse and addiction. The Institute carries out a large variety of
programs to inform policy and improve practice. Fact sheets on the
health effects of drugs of abuse and information on NIDA research and
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