Drugs Log

Two Baylor College of Medicine researchers in Houston are working on a cocaine vaccine they hope will become the first-ever medication to treat people hooked on the drug. “For people who have a desire to stop using, the vaccine should be very useful,” said Dr. Tom Kosten, a psychiatry professor who is being assisted in the research by his wife, Therese, a psychologist and neuroscientist. “At some point, most users will give in to temptation and relapse, but those for whom the vaccine is effective won’t get high and will lose interest.”

The vaccine, currently in clinical trials, stimulates the immune system to attack the real thing when it’s taken.

The immune system — unable to recognize cocaine and other drug molecules because they are so small — can’t make antibodies to attack them.

To help the immune system distinguish the drug, Kosten attached inactivated cocaine to the outside of inactivated cholera proteins.

In response, the immune system not only makes antibodies to the combination, which is harmless, but also recognizes the potent naked drug when it’s ingested. The antibodies bind to the cocaine and prevent it from reaching the brain, where it normally would generate the highs that are so addictive.

“It’s a very clever idea,” says David Eagleman, a Baylor neuroscientist. “Scientists have spent the last few decades figuring out reward pathways in the brain and how drugs like cocaine hijack the system. It turns out those pathways are difficult to rewire once they’ve seen the drug. But the vaccine just circumvents all that.”

Kosten asked the Food and Drug Administration in December to green-light a multi-institutional trial to begin in the spring and is awaiting a response.

Approval would mark a breakthrough in the treatment of cocaine addiction, which now mostly involves psychiatric counseling and 12-step programs. It presumably would be the final clinical hurdle before the vaccine — more than a decade in the making — might be approved for treatment. But one expert warns against expecting too much.

“Addiction vaccines are a promising advance, but it’s unlikely any treatment in this field will work for everyone,” said Dr. David Gorelick, a senior investigator at the National Institute on Drug Abuse. “Still, if they prove successful, they will give those working in drug addiction an important option.”

Scientists testing vaccine for cocaine users

Nothing says drug addiction more than a needle and syringe. But that’s exactly what a team of U.S. researchers believes can help cocaine users kick their menacing habit.

Two Baylor College of Medicine scientists based in Houston have developed a cocaine vaccine that creates antibodies that bind to the drug and prevent it from travelling from the bloodstream to the brain.

Unable to penetrate the brain, the drug can produce no high.

If the vaccine makes it through regulatory hurdles, it would be the first medication approved to treat cocaine addiction.

“It certainly is a way of combining immunology that had not been used before,” Tom Kosten, a professor of psychiatry and neuroscience at Baylor, said in a telephone interview yesterday. “We had always thought of altering the brain as a way to prevent drug abuse. This way, the drug never gets into the brain to begin with.”

Drug addiction treatment has largely been psychiatric counselling and 12-step programs. Dr. Kosten said that won’t go away – any approved vaccine would be complementary to behavioural therapy.

“If it’s approved in the U.S., then getting approval in Canada won’t be that difficult,” he said, adding that, if all goes well, a cocaine vaccine could be available in the United States in four years.

About 50 pharmaceutical options have previously been explored for cocaine addiction.

Dr. Kosten, who has been assisted in his decade-long research by his spouse, Therese Kosten, also a psychologist and neuroscientist at Baylor, asked the U.S. Food and Drug Administration last month to allow a Phase 3 clinical trial to begin this spring, involving 300 patients at six U.S. sites. Other trials are expected in Spain and Italy.

“Because there are no treatments for cocaine addiction, it’s been one of their fast-tracked programs at the FDA,” Dr. Kosten said. He is also at work on vaccines for heroin, nicotine and methamphetamine.

Yesterday, Evan Wood, co-principal investigator of the supervised injection facility evaluation in Vancouver, called the cocaine vaccine “new and provocative.”

“From a societal perspective, cocaine is one of the drugs that continue to be overlooked as one of the big problem drugs in our society,” said Dr. Wood, a physician epidemiologist at the British Columbia Centre for Excellence in HIV/AIDS.

“Crack cocaine is what is driving many of the social problems and public order problems and crime problems, particularly in the Downtown Eastside [of Vancouver].”

Dr. Wood said the “explosive HIV outbreak” in Vancouver’s east side is largely attributed to heroin users switching to cocaine, which leads to “more frequent injections, more chaotic behaviour and more syringe sharing.”

Learning about the immune system is opening all sorts of “avenues and possibilities,” said Dr. Wood. “But whether this is a useful tool remains to be seen.”

Certainly, the science is intriguing.

Since cocaine molecules are so small, the immune system does not recognize them and cannot make antibodies to attack them.

To fix that problem, Dr. Kosten attached inactivated cocaine to the outside of inactivated cholera proteins.

The immune system made harmless antibodies to the combination, but also recognized the drug when it was ingested. The antibodies bound to the cocaine, preventing it from reaching the brain, where the addictive highs are generated.

In Canada, there are no hard figures on how many are currently addicted to cocaine. Studies such as the Canadian Addiction Survey, published in 2004, found that more than 14 per cent of males, and 10.6 per cent of the total population, reported having tried cocaine.

Gerald Sidel, director of Addington Addiction Treatment Centre in Montreal, said yesterday that everybody is looking for the “magic bullet” to treat addictions.

He compared using modified cocaine to treat cocaine addicts to allowing alcoholics to engage in controlled drinking.

“Certainly if there is a way of helping people, I am not adverse to that,” Mr. Sidel said in a telephone interview yesterday. “But don’t treat drug addicts with drugs.”