In fact, the California researchers, together with the National Institute on Alcohol Abuse and Alcoholism, are now planning the first studies in humans of the drug's effectiveness in curbing alcohol cravings and dependence, Bartlett said. That the drug is already Food and Drug Administration-approved should speed things along.

"This is a drug that people are actually using. That's not trivial — not at all," said Mark Egli, co-leader of the medications development program at the NIAAA, part of the National Institutes of Health. "There is plenty of animal research that looks pretty cool but there is no way those drugs are ever going to be used by human beings."

In the new study, researchers trained rats to drink alcohol and measured the effect of varenicline once the animals became the laboratory equivalent of heavy drinkers. They found the drug curbed their drinking. Even when stopped, the animals resumed drinking but didn't binge.

Just as varenicline doesn't work for all smokers, it's highly unlikely it would for all drinkers.

"Is this going to be a cure-all? No, not for smoking or alcoholism because both diseases are more complicated than a single target or single genetic issue," said Allan Collins, a professor of pharmacology at the University of Colorado who was not connected to the study.

Still, Collins, who's worked on the topic for decades, called the drug's potential use in treating alcoholism a "no-brainer." And Egli said it supports the emerging view that there is a common biological basis for addictions to both alcohol and tobacco.

As for Pfizer, the New York company has yet to decide whether to seek broader FDA approval for the drug, a spokesman said.

"Without having considerable more data on this it would be very difficult for us to say we might pursue it or not. It's almost a wait-and-see," said Pfizer's Stephen Lederer.