A Cochrane review [Abstract] 1 included 8 studies on naltrexoneat doses of 25 - 100 mg/day reporting long-term abstinence data (six months or more) with over 1200 smokers. All studies were randomized and double-blind and 6 studies confirmed abstinence with biochemical verification (exhaled carbon monoxide or plasma cotinine). There was no significant effect of naltrexone on long-term abstinence (OR 1.26, 95% confidence interval 0.80 to 2.01). No significant difference was detected between naltrexone and placebo (RR 1.00; 95% CI 0.66 to 1.51; n=445), or between naltrexone and placebo as an adjunct to NRT (RR 0.95; 95% CI 0.70 to 1.30; n=768). The estimate was similar when all 8 trials were pooled (RR 0.97; 95% CI 0.76 to 1.24; n=1213).
An RCT 2 recruited heavy-drinking smokers (n=150) and randomized them to receive 10 weeks of either 50 mg naltrexone or placebo daily. Participants received 6 weeks of transdermal nicotine patch and 6 sessions of counseling that addressed both heavy drinking and smoking. Participants were followed for 26 weeks after their target quit smoking date.There were substantial reductions at follow-up in percent heavy drinking days and average drinks per week. However, participants receiving naltrexone did not differ significantly from those receiving placebo on percent heavy drinking days (effect size d = -0.04, 95% CI -0.30 to 0.22) or average drinks per week (d = -0.09, 95% CI -0.35 to 0.18) during follow-up. Naltrexone compared to placebo was not associated with a significant increase in smoking abstinence rates during follow-up (odds ratio = 0.93, 95% CI 0.46 to 1.86, p = 0.83). The effect of naltrexone on these outcomes was not significantly moderated by current alcohol dependence or gender.
Another RCT 3 enrolled adult smokers (n=315) in a 12-week of 50 mg naltrexone for smoking cessation. Participants were categorized into subgroups based upon past 6-month drinking patterns: Heavy drinking smokers (n = 69; averaged HASH(0x2fcfe80)2 heavy drinking episodes per month), moderate-to-light drinking smokers (n = 204, consumed 1 drink up to a maximum of <2 heavy drinking episodes per month on average), or nondrinking smokers (n = 42, no alcohol). Main study outcomes were biochemically verified prolonged abstinence quit rates, and smoking urge and alcohol use (drinks/wk) during treatment. Prolonged abstinence quit rates at week 12 were 32% (placebo) vs 10% (naltrexone) for non drinking smokers, 25% vs 25% for moderate-to-light drinking smokers, and 15% vs 32 % for heavy-drinking smokers. Naltrexone increased 12-week smoking abstinence rates and decreased smoking urge and alcohol use among heavy drinking smokers, but not moderate-to-light or nondrinking smokers.
A pilot study 4 examined whether naltrexone and bupropion combination treatment can help weight loss and smoking cessation in male obese patients with schizophrenia (n=22). Participants were randomized to receive adjunctive naltrexone (25 mg/day) and bupropion (300 mg/day) combination or placebo for 24 weeks. Body weight, body mass index (BMI), fasting lipids, smoking urge, expired carbon monoxide (CO) level and cigarettes smoked per week were measured at baseline and week 24. There was no significant difference between the groups in changes in weight, BMI, fasting lipids, or cigarette smoking measures (p's > 0.05).
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