A drug used to treat depression and certain other disorders. It is also used to help people stop smoking. Bupropion hydrochloride increases the levels of the chemicals dopamine, serotonin, and norepinephrine in the brain. This helps improve mood and can lessen cravings for nicotine. It is a type of antidepressant and a type of nicotine receptor antagonist. Also called Wellbutrin and Zyban.