Monday, 9 December, 2002, 00:00 GMT

DRUG COULD HELP COCAINE ADDICTS

A drug used to treat patients with cystic fibrosis and heart disease could
also help cocaine addicts to quit their habits.

Researchers in the United States have found that n-acetyl cysteine (NAC)
can help to reduce craving in cocaine users.

The medication eliminates the 'rewards' associated with taken the drug,
which keeps addicts wanting more.

Tests on rats have proved so effective that human trials are now being planned.

Researchers at the Medical University of South Carolina have found that NAC
has an impact on glutamate levels in the brain.

Previous studies have shown that this chemical plays a key role in cocaine
dependence.

Long-term use of cocaine interferes with normal glutamate levels. If
addicts stop using the drug, glutamate levels plunge.

Addicted Rats

Small amounts of cocaine can produce a large increase in this chemical,
although only for a short period.

It is this surge that encourages addicts to keep seeking the drug.

But Dr David Baker and colleagues have found that NAC can help to restore
glutamate levels to their normal levels.

Tests on rats have also shown that it stops the subsequent surge associated
with taking cocaine.

"Treatment with n-acetyl cysteines not only restores glutamate to normal
levels but also prevents glutamate levels from spiking following subsequent
cocaine injections," Dr Baker said.

The tests on rats also found NAC can reduce craving.

In this study, the rats were trained to self-administer cocaine injections
by pressing a lever.

When rats become used to the drug it is replaced with saline causing
withdrawal. The rat usually continues to press the lever for another two
weeks in the hope of obtaining cocaine.

When they stop pressing the lever, they are given an injection of cocaine.
This prompts them to start pressing the lever again or craving the drug.

'Encouraging'

However, the researchers found that NAC stopped the rats from craving the drug.

NAC is routinely used to treat patients with cystic fibrosis and bronchitis.

It is also taken as a supplement by people with heart disease and is
increasingly believed to help patients with HIV.

Dr John Marsden, a senior lecturer in addiction studies at the Institute of
Psychiatry in London, said the findings were encouraging.

However, he added that extensive studies in humans would be needed before
the medication could be administered to cocaine addicts.

"If there is a medication that would influence glutamate levels that could
be really encouraging.

"There could be a potential role of this NAC agent as part of relapse
prevention therapy."

Speaking to BBC News Online, he added: "This study is encouraging but we
need rigorous clinical trials in humans."

The findings were presented at the American College of
Neuropsychopharmacology annual meeting in San Juan, Puerto Rico.