Bupropion hydrochloride was originally marketed as an antidepressant but it has also been found to be effective in helping people to give up smoking. It reduces people's cravings for cigarettes but noone knows quite how it works. A team of researchers from the University of California Los Angeles studied 30 people all of whom were hooked on cigarettes. Over an eight-week study half of them were given bupropion and half were given a placebo. The participants who had been given bupropion reported fewer cravings and less activation in the left ventral striatum, the right medial orbitofrontal cortex and the bilateral anterior cingulate cortex than those who were taking a placebo. All the participants showed reduced brain activity in the bilateral medial orbitofrontal cortex and the left anterior cingulate cortex when they were trying to resist tobacco cravings suggesting that bupropion works by dampening down these areas of the brain.
Culbertson, Christopher S. ... [et al] - Effect of Bupropion Treatment on Brain Activation Induced by Cigarette-Related Cues in Smokers Archives of General Psychiatry doi:10.1001/archgenpsychiatry.2010.193