Can a drug cure an addict?

Researchers are working on a vaccine that could neuter the effects of narcotics like cocaine. Some experts warn this magic bullet could backfire

A man is at a downtown loft party. He knows he shouldn't be there, but a friend convinced him it would be a good time, one not to miss.

The music, the short skirts and familiar faces set off an urge he has been fighting for six months. It's been that long since he last cut cocaine. And he swore to stay clean.

But tonight, the pull is too strong. In a bathroom, after a quick exchange, he gets his fix.

He waits a few minutes. Yet the euphoria does not come. The vaccine worked – it stopped the cocaine molecules swirling in his blood from reaching his brain – and the man, even after giving in to temptation, does not spiral back into addiction.

The man in this scenario does not exist. But in as few as five years, this experience could be very real for the hundreds of thousands of people in North America who struggle with cocaine addiction.

In an ever-widening search to treat addiction, scientists have homed in on vaccines as a way to help people kick their habits for good. They say the powerful technology holds promise as an innovative way to treat drugs of abuse, including cocaine, methamphetamine, and even nicotine.

Human trials for the nicotine and cocaine vaccines are already well under way and have yielded good results. The National Institute for Drug Abuse in the U.S. has put $15 million toward research.

The promise of a magic bullet, a quick fix that would tear people away from drug dependency, is enticing to researchers, clinicians and addicts alike. But even as the technology is being perfected in laboratories, experts doubt that a single type of treatment will be able to solve addiction, a complex puzzle that affects dozens of brain processes and arises from myriad environmental, economic and social situations.

Anti-addiction vaccines also come with a host of ethical dilemmas: Should parents be allowed to inoculate their children against cocaine and nicotine?

Should convicted drug offenders have to be vaccinated against their illegal habit before entering prison? Should a vaccine be forced upon people, whether a person with mental illness or a pregnant mother, to protect their health?

Despite these concerns, proponents say vaccines, if and when they are shown to be safe and effective, will hold an important niche in addiction treatment and therapy.

There needs to be a wide variety of options since people respond differently to different treatments, says Margaret Haney, an associate professor of clinical neuroscience at Columbia University who studies medications, including a vaccine, to treat cocaine dependence.

Right now, she says, there are not enough medications available to treat most types of drugs of abuse, particularly cocaine.

"A vaccine is not going to cure cocaine addiction," she says.

"But there is a subset of people who will benefit from this approach ... There is a great call out there among people who are dependent, and from their family members, for something to help."

Anti-addiction vaccines employ immunotherapy and work by setting the body's immune system against drug molecules floating in the blood.

Normally, cocaine and nicotine molecules are too small for the body to recognize and easily pass from the bloodstream into the brain, where they set off pleasure receptors and produce a high.

To create a vaccine, scientists pair drug molecules with proteins to increase their overall size.

This forces the body to recognize them and to start producing antibodies against them.

After several inoculations, a patient who tries to use drugs will have enough antibodies in their blood to fight the new drug molecules, which are then prevented from reaching the brain.

The antibodies are excreted with no lasting effects.

Since vaccines target drugs before they reach the brain, scientists predict patients should experience fewer side effects.

Most other medications used to treat addiction work by changing neural pathways in the brain that mediate the effects of a particular drug.

At Columbia, in 2003, Haney tested a cocaine vaccine on 10 people who had no plans to quit using the drug.

After a course of four vaccines injected over a 12-week period, half of the people produced sufficient levels of cocaine antibodies and reported a substantial decrease, up to a 70 per cent drop, in their dependence.

Haney says the results are exciting.

One of the concerns with a cocaine vaccine is that once inoculated against a cocaine high, determined users will seek other drugs. But Haney's subjects did not do that.

"On the outside, they were using less cocaine. They just stopped. None of them switched to another drug of abuse."

A 2005 Yale University clinical trial of 18 cocaine addicts in early treatment found that cocaine antibodies persisted in the blood six months after inoculation, and subjects reported the usual euphoric effect of cocaine had diminished.

Clinical trials of nicotine vaccines have also met with success and experts say one of these vaccines will likely hit the market in as little as three years.

A 2005 clinical trial out of the University of Minnesota looked at NicVAX, a vaccine produced by Nabi Biopharmaceuticals based in Boca Raton, Fla. It found 38 per cent of smokers who received a higher dose of the vaccine quit smoking for one month, compared with 9 per cent of the placebo group.

"This is proof of principle that this (vaccine) can help people quit smoking," says study author Dorothy Hatsukami, the Forster family professor in cancer prevention at the University of Minnesota.

She sees the vaccine as a tool to help determined quitters from relapsing.

"Nothing is going to be a miracle cure," she says.

"Cigarette smoking is about more than just the drug itself. It includes a lot of things, the social environment, the pleasure sensory of smoking, using it to deal with stress. There are a lot of factors associated with smoking that people still need to deal with ... It (quitting) will still be a struggle, but it's always good to have something to help with the struggle."

Scientists who are working on anti-addiction vaccines see both the promise and the challenges that lay ahead.

Before the nicotine or cocaine vaccines can get to market, scientists have to figure out how to make them more effective, says Paul Pentel, professor of medicine and pharmacology at the University of Minnesota and a pioneer in the field.

It is clear, he says, from the three nicotine and one cocaine clinical trials that the more antibodies a person can produce, the better their chance of not using the drug. The clinical trials have also shown that not everybody who gets the vaccine will produce enough antibodies. Scientists don't yet exactly know why this happens.

"It needs to be improved to be generally useful and to get the most out of it," says Pentel.

Experts also say the mounting excitement over anti-addiction vaccines has to be tempered. Many people think of vaccines as a cure-all. And in most cases that is true; a shot against, say, measles, will prevent the disease from striking.

But anti-addiction vaccines work more like medication, says Pentel. People will likely need multiple doses over many months or years. Vaccines won't curb cravings or deal with the underlying reasons for addiction. And, in their current form, they certainly will not stop people from seeking drugs in the first place.

Haney at Columbia is adamant that people are not vaccinated against their will.

"If parents want to vaccinate their kids, I feel very strongly that that will be a disaster," she says. "The only appropriate use is for somebody who is very motivated to quit."

Tony George, a professor and chair in addiction psychiatry at the University of Toronto, says anti-addiction vaccines will be used in treatment programs once they are proven to be safe and effective. Clinicians are always looking to have more tools to help clients stay clean for good.

"This will be a bonus to our armoury," he says. "It just increases our repertoire and our chances of success."

source: The Toronto Star
Megan Ogilvie
Health Reporter