Using selective cannabinoid 1 (CB1) receptor antagonists such as rimonabant (Acomplia® at a dose of 20 mg per day can help people quit smoking, can help them to remain abstinent, and can help prevent the weight gain that so often accompanies attempts at stopping smoking. The lower dose of 5mg, however, was not shown to be effective, according to a Cochrane Systematic Review.
Smoking tobacco sends nicotine into the blood stream, and this chemical disrupts the endocannabinoid system, part of the hormonal control mechanism in the brain that controls energy balance and food intake. Over time the body alters the nature of its energy mechanism to compensate for this effect. Stopping smoking removes the nicotine and once again disturbs the mechanism, adding to the withdrawal symptoms and leaving a person prone to put on weight.
One potential way of preventing this is to take a drug that blocks the receptor that is involved in nicotine's action in the brain - the cannabinoid 1 receptor. These CB1 receptor antagonists could therefore form part of a therapeutic program aimed at helping individuals quit smoking, although this drug has not yet been approved as a smoking cessation treatment in the USA or in Europe.
To see whether there was evidence that these receptor antagonists work two Cochrane Researchers, Kate Cahill who works at the Department of Primary Care in the University of Oxford and Michael Ussher of St George's, University of London, searched the published and unpublished literature for relevant research projects. They found three trials that involved a total of 1567 smokers and 1661 people who had recently quit smoking. Analysing the data showed that the effect of the drug depended on the dose used:"From the preliminary data that we found it appears that 20mg rimonabant may significantly increase a person's likelihood of quitting and may also reduce the amount of weight that they gain," says Cahill.
Cahill K, Ussher M. Cannabinoid type 1 receptor antagonists (rimonabant) for smoking cessation Cochrane Database Syst Rev. 2007 Jul 18;(3):CD005353 [Full review]