Naltrexone, an opioid antagonist approved in 1994 by the U.S. Food and Drug Administration for alcohol-dependence (AD) treatment, can reduce relapse rates among AD patients. Research on naltrexone's effectiveness on nicotine dependence is less clear, although researchers believe it may be helpful for specific smoker subgroups. A new study has found that naltrexone can help non-AD smokers who drink heavily on a social basis.
Results will be published in the June issue of Alcoholism: Clinical & Experimental Research and are currently available at Early View.
"This was a smoking cessation trial," explained Andrea C. King, a psychologist and associate professor in the department of psychiatry at the University of Chicago, and first author of the study. "We examined smokers who did not have any other current addiction - besides tobacco - or mental or medical disorders, which may have confounded the results. The range of alcohol drinking was from abstainer to heavy social drinker."
King and her colleagues examined 78 study participants (43 men, 35 women) drawn from a larger study looking at the effectiveness of naltrexone on smoking cessation. Of the 78, 34 were randomly assigned to receive naltrexone; 44 received a placebo. Dosage at 25 mg daily began three days prior to the quit date, and then continued at 50 mg daily for eight weeks. Drinking and liver enzyme levels were monitored, and all participants received nicotine patches (to ease withdrawal symptoms) and behavioral counseling for up to four weeks following the quit date.
"Naltrexone, at 50 mg oral daily, when added to counseling and patch, significantly decreased heavy drinking rates in smokers enrolled in smoking cessation," said King. "Persons with the heaviest drinking patterns appeared to benefit the most from naltrexone, in terms of alcohol and smoking outcomes; it also increased their quit rates more so than in lighter drinkers."
King noted that that these results are likely based on the strong inter-connections between drinking and smoking for many individuals.
"Both nicotine and alcohol may stimulate brain reward pathways connected to endogenous opioids - meaning the 'endorphins' which are feel-good brain chemicals - as well as dopamine," she said. "An opioid blocker like naltrexone therefore may benefit persons who use both substances concurrently." She and her research team are trying to replicate these findings with a larger group of participants.
"If we do support these findings with a larger sample, then use of naltrexone could be expanded to drinkers-smokers who are trying to quit smoking," she said. "While quitting smoking is difficult for many, it may be especially hard for smokers who also drink alcohol, because the two are often used together, and drinking can dose-dependently trigger smoking urges and behavior. A medication like naltrexone, in addition to a standard quality smoking cessation program, may help this hard-to-treat subgroup of smokers who face additive health consequences from the co-use of these substances. This is significant also because naltrexone is well tolerated and safe."
Until then, she advised individuals who are trying to quit smoking to create a clear plan of action. "Stick with your plan, and learn from your mistakes, and try again if not successful. For some, it takes several attempts before being successful. FDA-approved medications and either group or individual counselling improve one's chances substantially. Tobacco is the number one modifiable health problem of our time. Persons with alcohol problems who also smoke are at more risk of dying prematurely from tobacco-related causes than they are of alcohol-related causes."
Alcoholism: Clinical & Experimental Research (ACER) is the official journal of the Research Society on Alcoholism and the International Society for Biomedical Research on Alcoholism. Co-authors of the ACER paper, "Naltrexone Decreases Heavy Drinking Rates in Smoking Cessation Treatment: An Exploratory Study," were: Dingcai Cao of the Department of Surgery, Catherine Vanier of the Pritzker School of Medicine, and Tracie Wilcox of the Department of Medicine, all at the University of Chicago. The study was funded by the University of Chicago Cancer Research Center, the General Clinical Research Center, and the National Institute on Alcohol Abuse and Alcoholism.