Passive vaccine could treat cocaine overdose

Much of the anti-drug vaccine research to date has focused on active vaccination, such as a heroin vaccine in development in Mexico, or the cocaine vaccine using Immunovaccine's adjuvant. Other approaches include antibodies that degrade the drug. Scripps Research Institute is developing a passive vaccine--anti-drug antibodies that capture the drug and stop it from having an effect--to treat cocaine overdose and it has seen promising results in animals.

In the study, published in Molecular Pharmaceutics, the researchers used genetically engineered mice to create a monoclonal antibody, code-named MAb GNCgzk, which binds to cocaine. In mice given a normally lethal overdose, treatment with the passive vaccine within a few minutes protected about 80 percent of the treated mice, but half of the untreated mice died. When the researchers created a "stripped down" version, with just a fragment of antibody (F(ab')2-gzk), a low dose reversed the effects of the cocaine within seconds.

"This would be the first specific antidote for cocaine toxicity," said Kim Janda, Ph.D., senior author of the report and professor in the Department of Immunology and Microbial Science. "It's a human antibody so it should be relatively safe, it has a superior affinity for cocaine, and we examined it in a cocaine overdose model that mirrors a real-life scenario." The researchers plan clinical trials if they can produce economically-viable quantities of the antibody fragment.

Despite years of research, few addiction vaccines have made it into the clinic, and there are none available on the market. This passive approach may not only treat patients in a cocaine overdose, which causes around 5,000 deaths a year in the U.S., but could also reduce the risk of relapses in the next few weeks as it remains in the circulation of the body for a while. It could also support patients in detox, but would not have the same long-term effect as an active vaccine.

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- see the abstract