A study on the Chantix drug which supposedly helps people quit smoking may also help in cutting off alcohol cravings.  The drug works by blocking nicotine receptors in the brain. Many people who have taken the drug to quit smoking have reported that their urge to drink was significantly reduced as well.

For the study, researchers recruited 15 healthy young adults ranging from moderate to heavy social drinkers (but were not alcohol dependent). On average, they drank at least 10 drinks a week and binged on alcohol at least once a week; they were also light smokers (fewer than five cigarettes daily). From WebMD:
Each person in the study visited the lab six times. In three of those sessions they were given a placebo pill. In the other three, they were given a single dose of the drug Chantix.

Three hours after they took their pills, they were asked to drink a beverage that contained either no alcohol, a low dose of alcohol, or a high dose of alcohol. The low dose was about two drinks' worth of alcohol. The high dose had about as much alcohol as in four drinks, and it was enough to legally intoxicate someone.

The order of the sessions was scrambled so people wouldn’t know which pill they were taking or how much they were drinking.

Before each session, researchers asked people questions about how they were feeling. They also measured their heart rate and blood pressure. People were also asked to put on special goggles that tracked their eye movements as they tried to follow a moving light.
Those who took Chantix reported increased feelings of nausea and generally feeling unwell after drinking, compared to the placebo. The reason may be that alcohol and nicotine may both exert their influence through the same receptor on brain cells, and since Chantix blocks that receptor, it could also help blunt some of the physical effects of alcohol.