Do opioid antagonists such as naltrexone help people to stop smoking?

David SP., Lancaster T, Stead LF, Evins AE, Cahill K

Published Online:

October 7, 2009

While nicotine replacement therapy and certain antidepressants help people to stop smoking, their overall effect is small because nicotine dependence involves many factors including learned behaviour, social settings and the effects of various drugs. Naltrexone is a long-acting drug (an opioid antagonist) which blunts the effects of narcotics such as heroin and morphine and might help reduce nicotine addiction by blocking some of the rewarding effects of smoking. Our review found that there is not enough evidence (with four trials covering 582 smokers) to show the effect of opioid antagonists such as naltrexone on smoking cessation. The effects of some opioid antagonists (e.g. naltrexone, naloxone: 13 trials covering 455 smokers) on withdrawal symptoms and the pleasurable effects of smoking are as yet unclear.

Abstract (click to read)

Background:

The reinforcing properties of nicotine may be mediated through release of various neurotransmitters both centrally and systemically. People who smoke report positive effects such as pleasure, arousal, and relaxation as well as relief of negative affect, tension, and anxiety. Opioid (narcotic) antagonists are of particular interest to investigators as potential agents to attenuate the rewarding effects of cigarette smoking.

Objectives:

To evaluate the efficacy of opioid antagonists in promoting long-term smoking cessation. The drugs include naloxone and the longer-acting opioid antagonist naltrexone.

Search strategy:

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) for trials of naloxone, naltrexone and other opioid antagonists and conducted an additional search of MEDLINE using 'Narcotic antagonists' and smoking terms in June 2009. We also contacted investigators, when possible, for information on unpublished studies.

Selection criteria:

We considered randomized controlled trials comparing opioid antagonists to placebo or an alternative therapeutic control for smoking cessation. We included in the meta-analysis only those trials which reported data on abstinence for a minimum of six months. We also reviewed, for descriptive purposes, results from short-term laboratory-based studies of opioid antagonists designed to evaluate psycho-biological mediating variables associated with nicotine dependence.

Data collection and analysis:

We extracted data in duplicate on the type of study population, the nature of the drug therapy, the outcome measures, method of randomization, and completeness of follow up. The main outcome measure was cotinine- or carbon monoxide-verified abstinence from smoking after at least six months follow up in patients smoking at baseline. Where appropriate, we performed meta-analysis using a fixed-effect model (Mantel-Haenszel odds ratios).

Main results:

Four trials of naltrexone met inclusion criteria for meta-analyses for long-term cessation. All four trials failed to detect a significant difference in quit rates between naltrexone and placebo. In a pooled analysis there was no significant effect of naltrexone on long-term abstinence, and confidence intervals were wide (odds ratio 1.26, 95% confidence interval 0.80 to 2.01). No trials of naloxone or buprenorphine reported long-term follow up.

Authors' conclusions:

Based on limited data from four trials it is not possible to confirm or refute whether naltrexone helps people who smoke, to quit. The confidence intervals are compatible with both clinically significant benefit and possible negative effects of naltrexone in promoting abstinence. Data from larger trials of naltrexone are needed to settle the question of efficacy for smoking cessation.

This record should be cited as:

David SP., Lancaster T, Stead LF, Evins AE, Cahill K. Opioid antagonists for smoking cessation. Cochrane Database of Systematic Reviews 2006, Issue 4. Art. No.: CD003086. DOI: 10.1002/14651858.CD003086.pub2

Assessed as up to date:

June 12, 2009

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Primary Review Group:

Tobacco Addiction Group

Health topics:

Lungs & airways > Smoking cessation > Pharmacological interventions

Tobacco, drugs, & alcohol dependence > Tobacco > Pharmacological interventions

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Do opioid antagonists such as naltrexone help people to stop smoking?

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