Long-term use of nicotine can upset the endocannabinoid system in the brain, which controls food intake and energy balance. Rimonabant and similar drugs may help smokers to quit by rebalancing the system, which then reduces nicotine and food cravings. We searched our own specialised register of controlled trials. We also contacted Sanofi Aventis, the manufacturers of rimonabant, and researchers who presented early findings at conferences. We found two randomized controlled trials (RCTs) of rimonabant for smoking cessation, covering 1567 smokers, and one RCT of rimonabant for relapse prevention covering 1661 quitters. The available information shows that rimonabant at the 20 mg dose increased by 1½-fold the chances of not smoking at one year, compared with placebo. Rimonabant 5 mg did no better than placebo at any time point. In the relapse prevention trial, smokers who quit successfully with rimonabant 20 mg were 1½ times more likely to remain abstinent on active treatment (5 mg or 20 mg for 42 weeks) than on placebo. For those who quit successfully on 5 mg, neither active nor placebo treatment appeared to benefit them in avoiding relapse. This inconsistent picture makes it difficult to find a clear benefit for rimonabant in preventing relapse. One trial of taranabant (317 smokers) did not find a benefit for treatment over placebo, and the taranabant group suffered more side effects than the placebo group. Main side effects for rimonabant included nausea and upper respiratory tract infections, and serious harms were reported to be low. For taranabant, the main side effects included problems with digestive, nervous, psychiatric, skin and blood vessel organ systems. For both drugs, the number and severity of the side effects increased in those taking higher doses. Although the evidence on weight change is sparse in these trials, weight gain was reported to be significantly lower among the rimonabant 20 mg quitters than in the 5 mg or placebo quitters. During treatment, overweight or obese smokers tended to lose weight on 20 mg, while normal weight smokers did not. Taranabant also limited weight gain during cessation attempts. In 2008 both rimonabant and taranabant were withdrawn by the manufacturers, because of links to mental disorders and unacceptable side effects.
From the trial reports available, rimonabant 20 mg may increase the chances of quitting approximately 1½-fold. The evidence for rimonabant in maintaining abstinence is inconclusive.
Rimonabant 20 mg may moderate weight gain in the long term. Taranabant 2-8 mg may moderate weight gain, at least in the short term.
In 2008, development of both rimonabant and taranabant was discontinued by the manufacturers.
Selective type 1 cannabinoid (CB1) receptor antagonists may assist with smoking cessation by restoring the balance of the endocannabinoid system, which can be disrupted by prolonged use of nicotine. They also seek to address many smokers' reluctance to persist with a quit attempt because of concerns about weight gain.
To determine whether selective CB1 receptor antagonists (currently rimonabant and taranabant) increase the numbers of people stopping smoking
To assess their effects on weight change in successful quitters and in those who try to quit but fail.
We searched the Cochrane Tobacco Addiction Review Group specialized register for trials, using the terms ('rimonabant' or 'taranabant') and 'smoking' in the title or abstract, or as keywords. We also searched MEDLINE, EMBASE, CINAHL and PsycINFO, using major MESH terms. We acquired electronic or paper copies of posters of preliminary trial results presented at the American Thoracic Society Meeting in 2005, and at the Society for Research on Nicotine and Tobacco European Meeting 2006. We also attempted to contact the authors of ongoing studies of rimonabant, and Sanofi Aventis (manufacturers of rimonabant). The most recent search was in January 2011.
Types of studies
Randomized controlled trials
Types of participants
Types of interventions
Selective CB1 receptor antagonists, such as rimonabant and taranabant.
Types of outcome measures
The primary outcome is smoking status at a minimum of six months after the start of treatment. We preferred sustained cessation rates to point prevalence, and biochemically verified cessation to self-reported quitting. We regarded smokers who drop out or are lost to follow up as continuing smokers. We have noted any adverse effects of treatment.
A secondary outcome is weight change associated with the cessation attempt.
Two authors checked the abstracts for relevance, and attempted to acquire full trial reports. One author extracted the data, and a second author checked them.
We found three trials which met our inclusion criteria, covering 1567 smokers (cessation: STRATUS-EU and STRATUS-US), and 1661 quitters (relapse prevention: STRATUS-WW). At one year, the pooled risk ratio (RR) for quitting with rimonabant 20 mg was 1.50 (95% confidence interval (CI) 1.10 to 2.05). No significant benefit was demonstrated for rimonabant at 5 mg dosage. Adverse events included nausea and upper respiratory tract infections.
In the relapse prevention trial, smokers who had quit on the 20 mg regimen were more likely to remain abstinent on either active regimen than on placebo; the RR for the 20 mg maintenance group was 1.29 (95% CI 1.06 to 1.57), and for the 5 mg maintenance group 1.30 (95% CI 1.06 to 1.59). There appeared to be no significant benefit of maintenance treatment for the 5 mg quitters.
One trial of taranabant was not included in our meta-analyses, as it followed participants only until end of treatment; at eight weeks it found no benefit for treatment over placebo, with an OR of 1.2 (90% CI 0.6 to 2.5).
For rimonabant, weight gain was reported to be significantly lower among the 20 mg quitters than in the 5 mg or placebo quitters. During treatment, overweight or obese smokers tended to lose weight, while normal weight smokers did not. For taranabant, weight gain was significantly lower for 2-8 mg versus placebo at the end of eight weeks of treatment.
In 2008, post-marketing surveillance led the European Medicines Agency (EMEA) to require Sanofi Aventis to withdraw rimonabant, because of links to mental disorders. The development of taranabant was also suspended by Merck & Co because of unacceptable adverse events.