October 6, 2009

Cocaine Vaccine May Be Future Hope For Treating Addiction

In the first successful study of a vaccination approach to treating drug addiction, a vaccine that uses the immune system to help block the euphoric effects of cocaine had a promising effect among 38 percent of subjects who received it, according to a Baylor College of Medicine researcher who headed the study.

While the shots did not have a perfect effect, the researchers believe the small success is promising enough to indicate that the new vaccine approach could be widely used to treat addiction within several years.

"It is such an important study. It clearly demonstrates ... that it is possible to generate vaccine that could interfere with cocaine actions in the brain," said Dr. Nora Volkow, director of the National Institute on Drug Abuse, which provided funding for the study.

The study's results were released within days of the government agency announcing plans for the first late-stage study of an experimental nicotine vaccine developed to help people quit smoking.

The Food and Drug Administration has pushed the NicVAX vaccine through, and the research will be funded by federal stimulus money.

Both the cocaine and nicotine vaccines work in the same way, by stimulating the immune system to produce antibodies that attach to molecules of the drugs and block them from reaching the brain.

The new study shows that cocaine-fighting antibodies helped keep users from experiencing a high from the drug while resulting in almost 40 percent of them substantially decreasing or stopping cocaine use at least temporarily.

Considering there are over 2 million cocaine abusers across the nation with no federally approved treatment, the results "are good enough - better than having nothing," said lead author Dr. Thomas Kosten of Baylor College of Medicine in Houston, who developed the vaccine used in the study.

The study is published in October's Archives of General Psychiatry, released Monday.

According to Volkow, the research is a model of a "transformative" perspective on drug addiction.

"By targeting it as a medical disease as opposed to a moral dilemma, we're likely to come up with solutions that have a much longer impact," she said.

The study involved 115 cocaine and heroin abusers who sought methadone treatment at a New Haven, Conn. clinic. Even though Methadone serves only as a treatment for heroin addiction, it requires repeat clinic visits. This made them available regularly for the researchers to work with and keep track of, Kosten said.

Over the course of a 12 week period, almost every participant received five shots of cocaine vaccine or a placebo substance. They were then followed for an additional 12 weeks.

The participants also took part in a weekly relapse-prevention therapy session, had their blood tested for antibodies and their urine tested for cocaine and heroin.

Of the 21 vaccine patients, 38 percent developed cocaine antibody levels high enough to prevent a cocaine high. In that group, 53 percent did not use cocaine during more than half of the duration of the study, whereas only 23 percent of those with lower antibody levels stopped.
Even though researchers referred to it as "limited success", the results are exciting and reveal that the vaccine approach is a good one, said Dr. Kyle Kampman, a University of Pennsylvania addiction researcher who was not involved in the study.
"We need novel approaches because cocaine dependence is a disease that has been very difficult to treat," Kampman said.

A 2007 National Survey on Drug Use and Health showed that 35.9 million Americans aged 12 and up reported having used cocaine, and 8.6 million reported having used crack, the solid smokable form of the drug.

In 2006, cocaine was responsible for about 14 percent of all admissions to drug abuse treatment programs.


On the Net: