The active ingredient in Zyban is bupropion hydrochloride, which is also present in certain anti-depressant medicines. The tablets are "sustained release" bupropion, which means the drug is slowly absorbed by your body.They do not contain nicotine. Zyban affects some of the areas of the brain that are affected by nicotine, and it is thought to work by acting on systems which play a role in brain reward for nicotine and withdrawal.
Using Zyban can help to reduce withdrawal symptoms when you quit, such as cravings, irritability, and difficulty concentrating. However, it may not stop these symptoms completely. Zyban may also make smoking seem less rewarding.
How well does it work?
People who use Zyban are nearly twice as likely to quit and stayed stopped, if they have counseling as well. Advice or counseling is provided by the Quitline or from your doctor, pharmacist or other trained advisor.
Although Zyban has been used as an anti-depressant, it is equally helpful to smokers with or without a past history of depression. Zyban reduces the weight gain that may occur after quitting, but the effect doesn't appear to last beyond its use.