Those findings come from a study of 403 heavy drinkers in Finland, who took either a placebo or the drug nalmefene on an "as needed basis."
"It has a robust and sustained effect in reducing harmful heavy drinking in a large study population," said researcher Sakari Karhuvaara. "Alcohol problems have huge negative impacts on the well-being of individuals and families and cause enormous costs to society due to lost working days, accidents, treatment of alcohol-related disease, etcetera."
Before the study, patients assigned to nalmefene treatment reported 15.5 average heavy drinking days each month. They were directed to take the drug whenever they felt a looming urge to drink. During the first three months of treatment, the average number of heavy drinking days was 8.6 to 9.3 for the people in the nalmefene group.
The drinkers assigned to the placebo group had somewhat less dramatic reductions. They averaged 16.2 heavy drinking days a month before the study and 10.6 to 12.0 during the trial.
Researchers double-checked participant-reported alcohol consumption changes with tests that measured alcohol-use biomarkers in the blood.
In the United States, abstinence has been the traditional goal of the treatment of alcohol dependence, but in the last 20 years, there has been a movement to consider harm reduction or drinking reduction as a goal equal to abstinence.
"Alcohol dependence is nowadays recognized as a chronic, recurring disorder where relapses almost inevitably occur during and after the treatment," Karhuvaara said. So focusing on harm reduction in the short term is often much more feasible than complete abstinence, he added.
Karhuvaara is a physician and health researcher who was once an employee of Biotie Therapies Corp., the manufacturer of nalmefene. The drug maker supported the new study.
"There are fair amounts of good data (showing) that the more drinks you have a day, the more likely you are to have health or social consequences," said alcohol researcher Raymond Anton.
"The thinking is that if you can reduce heavy drinking days or the number of drinks per drinking day, you might actually alleviate some suffering, even though you don't cause the person to be abstinent."
Not everyone who seeks alcohol treatment is ready to consider a lifetime without alcohol, so an abstinence goal can be a barrier for some people considering help.
Many health professionals are convinced that a harm reduction approach can draw more people into treatment, said Anton, director of the Center for Drug and Alcohol Programs at the Medical University of South Carolina. Anton did not participate in the Finnish study, but he has conducted nalmefene research in the United States.
The Finnish researchers note some side effects among people in the nalmefene group, including nausea, abdominal discomfort, as well as energy and sleep difficulties. However, most study participants remained in the trial and continued using the drug.
"I wish they'd done an analysis to see if the people who suffered those side effects were the same people who drank less. Perhaps some of the reduction in drinking may have been because they didn't feel so good, rather than because the drug just took away an urge to drink," Anton said.
Patients must take most medications for alcohol treatment daily. Nalmefene taken "as needed" fits into the harm reduction treatment approach.
The drug is an opioid antagonist that works to block the effects of endorphins. The U.S. Food and Drug Administration has not approved nalmefene for use in alcohol treatment; the drug is primarily available in investigational studies.
Karhuvaara said his study also suggests that "practically any doctor" could successfully administer nalmefene in a wide variety of medical settings.
"It is an attempt to get the drug out of the sole use of addiction specialists and into the hands of primary providers," Anton said.