Drinking too much is a deadly gamble at any time of year, but especially during the holidays. One answer for problem drinkers is naltrexone — a drug, taken daily, that curbs the urge to drink. But in order for the pill to work, you have to take it, making a commitment to sobriety every day. In 2006 the government approved a naltrexone injection that works for a full month. In a study conducted late last year, the injection got high marks, reducing the number of days on which the subjects drank and the amount they consumed when they slipped. These results were consistent throughout the year — even during the holidays, when the temptation and risks are greatest.