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News Release

Issued by the Press Office of the National Institute on Drug Abuse (NIDA)

December 14, 1995

Immunization Found To Effectively Block Effects of Cocaine

Researchers funded by the National Institute on Drug Abuse, National Institutes of Health, report that they have successfully immunized rats against many of the stimulant effects of cocaine. Cocaine was prevented from entering the brain when rats were "vaccinated" with a substance that triggers the body to produce antibodies to cocaine. These antibodies then acted as biological "sponges" to which cocaine binds, thereby reducing the amount available in the blood to reach the brain. The results of this research are presented in "Suppression of Psychoactive Effects of Cocaine by Active Immunization" in the December 14, 1995 issue of Nature.

Researchers Kim Janda, Ph.D., Rocio Carrera, M.A., George Koob, Ph.D., and colleagues at The Scripps Research Institute demonstrated a greater than 70% reduction in cocaine in the brains of rats inoculated with the antibody-producing compound as compared to a group which was not inoculated. Researchers designed the compound so that the antibodies produced would respond specifically to the cocaine molecule yet not affect normal brain chemistry.

"This is an exciting breakthrough for drug abuse treatment research" said Dr. Alan I. Leshner, Director of the National Institute on Drug Abuse. "Developing medications for the treatment of cocaine addiction is very high among the Nation's greatest needs in dealing with its drug problem, and it is NIDA's number one priority. Dr. Janda's research gives the scientific and medical fields a very promising new direction in the search for a safe means of blocking the damaging effects of crack and cocaine."

In the study, Dr. Janda and colleagues used an "active immunization" approach by developing a substance that when administered to rats would trigger the immune system to produce antibodies that are specific for the cocaine molecule. The researchers inoculated the rats over a 35 day period and then tested their responses to cocaine. The immunized animals showed significantly lower responses to the stimulant effects of cocaine than normal animals because the immunization prevented much of the cocaine from getting to the brain. Cocaine concentrations in the brain tissue of the immunized animals were found to be dramatically less than the concentrations of cocaine in brain tissue of controls.

Other immunotherapy research for drug abuse treatment has explored the use of catalytic antibodies and other external agents that can be used to treat cocaine dependence. The research reported in Nature differs by inducing the production of antibodies which remain in the bloodstream for an extended period of time and block cocaine's effects after it is used.

Dr. Koob said, "The potential advantage of such an approach is that immunization should have none of the side effects associated with medications that interfere directly with parts of the brain responsible for cocaine's action." Dr. Janda added, "The importance of our work is that we bring together three separate disciplines: chemistry, immunology and neuropsychopharmacology, to offer a sound scientific approach for the treatment of cocaine abuse."

The researchers identified a number of issues which must be explored before this approach is ready for clinical trials. It is not clear how long the immunization would remain effective in the bloodstream nor what the effects of repeated immunization (boosters) would be. In addition, there are questions about the dangers of people taking higher doses of cocaine to overcome the effectiveness of the immunization as well as bioethics about the use of vaccinations for drug treatment.

'While we are in the initial phase of this very interesting research, it opens up a whole new range of possibilities. One long term goal would be to use this type of research to develop a medication capable of immunizing cocaine users and addicts against the effects of cocaine," Dr. Leshner added.

The National Institute on Drug Abuse, part of the National Institutes of Health, is the primary federal agency responsible for basic, clinical, and applied research designed to improve and develop new strategies to deal with the health problems and issues associated with drug abuse and addiction. The development of new medications for treating drug addictions is a major part of NIDA's efforts.


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