PHA-Exch> Vaccine for drug addiction could offer hope to users

[Claudio Schuftan]

From: Vern Weitzel vern at coombs.anu.edu.au

Vaccine for drug addiction could offer hope to users

by Regan Doherty

CHICAGO (AFP) - In a search for what could be the ultimate cure for drug
addiction, scientists have developed a vaccine which prevents the body
from getting high.

The hope is that it can stop people from falling back into a spiral of
addiction if they have a relapse.

The most promising results so far have been with cocaine, but
researchers hope it could also one day be used to cure addiction to
methamphetamine, heroin and even cigarettes.

"The vaccine slowly decreases the amount of cocaine that reaches the
brain," said Thomas Kosten, a professor of psychiatry and neuroscience
at Baylor College of Medicine in Houston, who has been working on the
vaccine since 1995.

"It's a slow process, and patients do not go through any significant
withdrawal symptoms."

The vaccine works by getting the body's immune system to recognize the
drug as foreign and attack it in the blood stream.

It does so by injecting an altered version of the drug into the body
which has been attached to a protein that the body will recognize as a
threat.

"The body then says, 'This is a foreign article. I should start making
antibodies to it,'" Kosten said in a telephone interview.

The cocaine molecules eventually pass through the kidneys and are
excreted through the urine.

That stops the drug from reaching the brain and producing a sought-after
high.

Use of the vaccine would lead to a gradual tapering of dependence,
Kosten said.

"Gradually, antibody levels would rise. If you kept using (cocaine),
you'd get less and less of an effect."

Of all the drugs tested, cocaine is the easiest one for which to develop
a vaccine because of an enzyme in the bloodstream, cholinesterase, that
helps break it down, Kosten said.

He has also begun to test vaccines for methamphetamine and heroin in
animal studies, and hopes to eventually add nicotine to the list.

"That's going to be the moneymaker," he said.

The injections are designed for therapeutic -- not for preventative --
use, and are meant for those already suffering from addiction.

That, however, does not rule out other possible future uses, Kosten said.

"You could potentially inject pregnant cocaine users with the vaccine to
prevent their fetuses from becoming contaminated," he explained.

Other uses could include administering the vaccine to high-risk
adolescents in order to prevent them from becoming addicted early on, he
said, while acknowledging that this would raise serious ethical and
legal questions.

Testing for the cocaine vaccine has included a series of five injections
over a period of three months, Kosten said.

The vaccine has one more large scale human study scheduled before it is
ready for the federal Food and Drug Administration approval process.

A similar nicotine vaccine is also in the early stages of testing by
several groups of European researchers. Kosten hopes to have the vaccine
on the market in two to three years.
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