Alcoholic Rats Show Kudzu May Help Addicted Humans

Maggie Koerth-Baker
for National Geographic News

August 12, 2009

Kudzu—an invasive vine infamous for choking much of the southern U.S.—may end up being a lifeline for alcoholics, a new rat study shows.

Native to Asia, kudzu has long been used as a treatment for addiction by practitioners of traditional Chinese medicine. Accidentally introduced to the U.S. in the late 1800s, the fast-growing plant has smothered many native plants throughout the South.

(Related: "Kudzu Entrepreneurs Find Gold in Green 'Menace.'")

More than a decade's worth of studies have shown that extracts of kudzu can successfully reduce cravings and consumption of alcohol in both animals and humans. Now, researchers are exploring two ways of turning the plant into a medicine.

For the first time, researchers have attempted to synthesize a drug based on daidzin—a chemical component of kudzu identified as the possible source of the plant's powers.

Though kudzu extract is already available in health food stores, "it's not a good drug," said study leader Ivan Diamond, vice president of Gilead Sciences, a biopharmaceutical company that is working to develop a kudzu-based compound for humans.

That's because kudzu extract—unregulated by the U.S. Food and Drug Administration—is poorly absorbed by the body and its concentration varies wildly from bottle to bottle, he said.

"As a doctor, you want to know exactly how much of the active chemical gets into the blood and what it does there. Our idea is to take the best of this plant and make a controlled medicine."

A Rat Walks Into a Bar …

Diamond's team successfully tested a synthetic, kudzu-like compound called CVT-10216 on "alcoholic" rats, with help from scientists. (Diamond has a financial interest in Gilead and stands to profit if a drug based on CVT-10216 can be successfully marketed.)

Like college students, the rodents were eased into alcohol consumption by drinking sugar-water cocktails. Slowly, the drinks got stiffer. A variety of tests gauged the rats' desire for alcohol.

In the most significant test, researchers gave rats access to booze only in a special cage. Once the rats showed significant interest in alcohol—for instance, choosing it over water—the researchers made them go cold turkey for several weeks.

Then, the rats went back to the special cage, but this time without any booze. Alcoholic rats, however, remembered the drinking cage and frantically looked for liquor whenever they were there.

"For them, it was like walking into a bar," said Diamond, whose research appears in an upcoming issue of the journal Alcoholism: Clinical and Experimental Research.

But when alcoholic rats were given CVT-10216, going to "the bar" no longer made them as excited.

This suggests CVT-10216 has the power to reduce cravings and not just consumption—which means it could help prevent relapse, the researchers say.

Herbal Alternative

Since there's still a ways to go before human alcoholics can take CVT-10216, other researchers are working to make kudzu treatments that may reach the market faster.

Harvard Medical School psychiatrist Scott Lukas is part of a team developing a kudzu extract called Alkontrol-Herbal. Like Diamond, he holds a financial stake in his medication's success.

Lukas said Diamond's new research is unique and important, "but I can't tell people who are alcoholics now to hold out for ten years."

Alkontrol-Herbal, Lukas said, can reach alcoholics faster than CVT-10216 because there's no requirement that herbal medications and supplements go through the lengthy FDA approval process. Unfortunately, this also means consumers can't trust the labels on their herbals.

"We took all the over-the-counter kudzu preparations and analyzed them, and none had the amounts of active chemicals they claimed," said Lukas, also a pharmacologist at McLean Hospital in Massachusetts. "Most contained none at all."

In contrast Lukas says Alkontrol-Herbal would be an alternative to the alternatives, with strict quality control and scientific research backing it up.

In a 2005 study, also published in Alcoholism: Clinical and Experimental Research, Lukas and colleagues found that heavy drinkers who took the Alkontrol-Herbal extract drank fewer beers when offered the drinks a month later.

Alkontrol-Herbal should be on store shelves within nine months, Lukas added.

No Silver Bullet

There's no silver bullet for the treatment of addiction, so it's important to have a wide range of treatments, said David Overstreet, who studies alcoholic addiction at the University of North Carolina at Chapel Hill.

Overstreet has done research on both Lukas's kudzu extracts and Diamond's synthetic compounds, but he doesn't have a financial stake in either. Questions remain about both, he said.

For instance, Overstreet said, Alkontrol-Herbal hasn't been through an experiment that shows that it reduces cravings, as the CVT-10216 experiment did. The ability to fight cravings is a crucial function of any alcohol-addiction treatment. The synthetic compound has its own drawbacks.

For one, it's not known whether CVT-10216 will work as well in humans as it does in rats.

The rat experiment is superior because it's an experiment that offers proof of reduction of cravings, rather than just proof of reduction of drinking. The supplement hasn't been tested in a way to prove this crucial function. Ability to fight cravings is what makes this really unique because that means the drug can fight relapse.

And there's the compliance issue, Overstreet said: Anecdotal evidence suggests alcoholics are more likely to take herbal supplements than medicines, because people often don't want to feel like they have a disease.

(See photos: "Beyond the Brain" in National Geographic magazine.)

On the plus side, tests of both CVT-10216 and Alkontrol-Herbal show evidence of low, or even non-existent, side effects.

"We only know bits and pieces," Overstreet said, "but we do say there's enough evidence now to support proper clinical trials of these new [kudzu-based] medicines and herbal medicines."