PRESCRIPTION ADDICTION

Medications designed for one purpose often end up as treatments for other
conditions. That's not unusual. What is surprising is the number of older
drugs that have suddenly become good candidates for treating cocaine addiction.

Researchers at the National Institute on Drug Abuse are studying whether a
half-dozen medications used for such conditions as narcolepsy and influenza
can help people trying to abstain from cocaine and other addictive drugs.

Traditional therapy for cocaine addiction, which affects an estimated 1.5
million Americans, has centered on psychological counseling and behavioral
therapy.

But scientists are increasingly using drugs to treat drug dependence, an
effort stemming from an increased understanding of the brain's natural
chemicals and how foreign substances affect the brain.

The first of these studies is on selegiline, an old antidepressant that is
also used to help reduce the symptoms of Parkinson's disease. NIDA
researchers are expected to soon announce the results of a study in which
300 cocaine users were treated with either a selegiline skin patch or a
placebo.

"Selegiline is what I call a first-generation drug for cocaine dependence.
The majority of these will be drugs that are already marketed," says Dr.
Frank Vocci, director of medications development at the National Institute
on Drug Abuse.

Because such drugs are already widely available, doctors have an idea of
how they work in the body and how they might help treat drug dependence.

Selegiline is a monoamine oxidase inhibitor, meaning that it inactivates an
enzyme that breaks down brain chemicals important to mood and well-being.
MAO inhibitors fell out of favor years ago, however, because patients
taking them can have severe toxic reactions, even death, if they consume
foods containing tyramine, an amino acid found in cheese, sausage, soy
sauce, beer and many other foods.

The cocaine dependence study is using a new formulation of selegiline: a
skin patch that appears to avoid interactions with tyramine. The patch is
being developed by Somerset Pharmaceuticals in Tampa, Fla.

"With the patch, there are no dietary restrictions," Vocci says.

An earlier study in which cocaine users were given small doses of oral
selegiline indicated that it can help blunt the high that users feel, thus
curbing the desire to use again.

The drug elevates levels of a brain chemical called dopamine that appear to
be eroded by the use of cocaine and nicotine (selegiline is also being
tested for nicotine dependence).

But selegiline also appears to prompt the release of a chemical called
phenyl ethylamine. This substance is often called the "love chemical,"
Vocci says, because it's found in chocolate and has been linked to feelings
of love. The "love chemical" reputation is "urban science legend," Vocci
says. "It's still an interesting compound."

The institute has also launched a study on the effects of selegiline on
methamphetamine dependence because methamphetamines also affect dopamine
levels in the brain.

While selegiline is one of NIDA's first attempts at testing medications for
substance abuse, many other projects are underway. All of the studies,
Vocci notes, will be using medications along with behavioral therapies.
Research has shown that such an approach is more effective than drug
therapies alone, he says.

And later this year, NIDA will launch a study on a cocaine vaccine. The
goal is to prime the body to recognize cocaine as a foreign invader and
generate antibodies. Study volunteers will receive injections of the
vaccine and then will be followed for several months to gauge their cocaine
use.

Shari Roan writes for the Los Angeles Times.