Potential Vaccines for Other Addictive Drugs

Drug addiction researchers believe that it may be possible to develop similar vaccines for other addictive drugs. The concept for all of these vaccines is that they will bind to the brain-active chemical in the drug while it is still in the bloodstream outside the brain, and that the chemical that causes addicting effects will never be able to enter the brain.

Psychiatrist Thomas Kosten at the Baylor College of Medicine in Houston, Texas has been working on a different vaccine for cocaine addiction. He and his colleagues have been working on a treatment that "soaks up enough cocaine" in the bloodstream that only small amounts ever reach the brain. Unlike Janda's team at the Scripps Research Institute, Kosten and colleagues have tested their vaccine on human cocaine addicts.

The results were mixed.

The research team recruited 115 cocaine addicts from a community treatment center in West Haven, Connecticut. They randomly selected 58 volunteers to receive the vaccine and 57 volunteers to receive a placebo. All the volunteers were given 5 injections of vaccine or placebo over a 12-week period. (Five dropped out before the end of the study.) Kosten and colleagues measured antibody levels after each injection and also tested bloodstream levels of cocaine.

Just 38% of addicts who received all five injections built up antibody levels that were high enough to dull the effects of cocaine. And only about half of that 38% actually quit using the drug.

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Cocaine addicts who had received Kosten's vaccine did not get a high the next time they used cocaine. However, some cocaine addicts tried to compensate for the effects of the vaccine by using up to 10 times as much cocaine, or by buying cocaine from a variety of dealers. Some reported greater devastation to their finances after using the vaccine than before. (There is no indication that the researchers offered the cocaine addicts additional money.) About 1/4 of the volunteers who received the vaccine did not make any antibodies at all, and the effects of the vaccine seemed to wear off after 8 to 10 weeks.

Dr. S. Michael Owens has been developing a vaccine for methamphetamine abuse for InterveXion Therapies, a private biotech firm in Little Rock, Arkansas. His research takes into accounts that both "highs" and "lows" from using meth can be more severe than expected. His firm received preliminary approvals to begin clinical testing of his vaccines in 2010, and may begin testing on human volunteers in 2012.

Since drug addiction is a huge social problem, why aren't the big drug companies investing in research?

There are several strong reasons that the development of anti-addiction vaccines right now is dependent on the generosity of charitable funding organizations and the risk-taking of small biotech firms.

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• Large pharmaceutical companies don't want to become too closely identified with drug addiction.
• There is an even larger market for treating nicotine addiction with low-tech (and mostly unreliable) medications. After all, if a medication for nicotine addiction does not work, or you don't finish the box, there is always a possibility you will buy more.
• There is a lot more profit in a treatment you have to use every day than in a treatment you only need every few months.

Immunotherapy for drug addiction faces numerous scientific obstacles. But the greatest obstacle to realizing easy treatments for addiction may be that ineffective treatment earns a lot more money.