Researcher Closes in on Anti-addiction Vaccines

We tend to think of vaccines as protecting against infectious disease, but what if they could be formulated to help people ward off or kick drug addiction? For over 25 years, that has been the goal of Kim D. Janda, PhD, a professor of chemistry at the Scripps Research Institute.
 
As an article in today’s New York Times explains, Janda is working on vaccines that would prompt the immune system to produce antibodies that would prevent a given narcotic, such as nicotine or cocaine, from having an effect on the body or brain. As an example, cocaine addicts who received one of his experimental vaccines and then snorted cocaine reported feeling as if they had been given phony drugs.
 
In July, Janda’s lab announced it had produced a vaccine for rats that prevented heroin from having its customary pain-deadening effects. As a result, the rats were no longer interested in using heroin. So far, however, none of his vaccines have succeeded in human clinical trials.
 
Anti-addiction vaccines work on a principal similar to that of disease vaccines. They inject a small amount of a substance into the blood, prompting the immune system to produce antibodies that neutralize the substance if it shows up in the future.
 
The challenge is that, since drug molecules are far smaller than disease molecules, they are usually unnoticed by the immune system. To get around this problem, Janda attaches the drug molecule (or a synthetic version) to a larger protein to make it more noticeable and includes substances designed to draw the immune system’s attention.
 
So far, Janda has failed in attempts to make a vaccine against alcohol, whose molecules are too small to attach to a larger protein, and marijuana, whose active ingredient, THC, hides within the body. He has also tried to develop a vaccine against obesity that blocks the effects of a hormone called ghrelin that signals hunger; it has successfully reduced food intake in animals but has yet to prove itself in humans.
 
Even if the vaccines do ultimately succeed, they have some potential problems. One is that being vaccinated against the effects of one drug—for instance cocaine—would not prevent a user from becoming addicted to another drug, such as methamphetamines. Another is that someone vaccinated against a given drug would test positive for antibodies to the drug for up to six months, providing evidence that they had had problems with addiction.
 
Source
An Addiction Vaccine, Tantalizingly Close [New York Times]