Researchers say immunization is the way to go with cocaine addiction, in part because they have failed to develop a classical blocker that would prevent the drug from binding to cells in the brain. Theoretically, immunization would stop the cocaine in the bloodstream before it reached the brain.

Cocaine is also a good target because of its popularity and its potentially disastrous effects in heavy users -- it's one of the most highly addictive drugs available. Researchers say that anyone can develop an appetite for the drug, which binds to the normal dopamine transporter. Even lab animals get hooked after they've experienced cocaine highs. "Every mouse will self-administer cocaine; they will press the bar to the exclusion of food, or sex; they will press it until they die," says Kim Janda, professor of chemistry at Scripps Research Institute in La Jolla, Calif.

But repeated use is not simply a habit; cocaine alters brain function. "Opiates don't make you stop thinking correctly, but cocaine and amphetamines and methamphetamines actually change the way your brain works," says David Musto, professor of child psychiatry and the history of medicine at Yale. "And so you can get extremely paranoid that people are still after you." Janet knows this well: Two years after she quit taking drugs, she says, she still stays home many days because of intense anxiety attacks around people.

Scientists are investigating two immunization techniques. Active immunization works as a conventional vaccine does: It triggers the body to produce antibodies that bind to the cocaine and neutralize it. The second approach, passive immunization, uses injected antibodies that bind to the cocaine and break, or "catalyze," it into harmless fragments.

Janda and his colleagues recently completed a study on rats showing that a combination of the two techniques works best, and has less risk of relapse than using the active method alone. Janda's findings will be reported soon in the Proceedings of the National Academy of Sciences. And he will begin testing his approach on people in the next few months, in collaboration with Drug Abuse Sciences, a pharmaceutical company in Menlo Park, Calif.

Even if they turn out to work well, these immunization approaches have limitations. If users don't get the high they want, they might take more cocaine to override the effects of the vaccine. (With passive immunization with a catalytic antibody, researchers say, this shouldn't happen as easily.) Moreover, it takes several months to create the needed antibodies -- for example, two months for Kosten's vaccine -- which might be enough time for someone to give up on the treatment.

And if the pleasure of cocaine is blocked, a user can always jump to other drugs. "The thing I have learned about drugs is that if you're not getting the high that you want out of it, then you look for alternatives," Janet says. It's also important not to underestimate the craving that addicts have for substances like cocaine, even if they have been clean for years. If, as happened to Janet recently, a former user is in the same room with someone who has cocaine, it can trigger an intense yearning for the drug.

The difficulty in treating people who are trying to kick any drug habit goes beyond just biology. No matter how successful a vaccine is, addiction will still be a struggle for many people, researchers say. Typically, complicated psychological, social and personal histories interplay with drug abuse.

"Many have organized their lives around their addiction, and then when that is stopped, they have to find a new way of reorganizing their lives," says Don DesJarlais, director of research for Beth Israel Medical Center's Chemical Dependency Institute in New York.

Janet snorted her first line of cocaine when she was 18, just after being told she would never be able to have children because of an accident. She was already carrying a heavy emotional burden, she says, having been molested at age 4 and raped by several men at age 11.

When she looks back on the beginning of her habit and wonders if anything could have stopped her, Janet says that perhaps if she'd been living at home and her parents had dragged her to get vaccinated, and had monitored her, then maybe she would have stopped. But she insists, as do the researchers developing these vaccines, that all the medical attention in the world won't eliminate drug addiction. The key to quitting is having the desire, and the will, to quit.

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