What is bupropion and how does its mechanism differ from SSRIs?

Bupropion is an atypical antidepressant that inhibits the reuptake of norepinephrine and dopamine but has no effect on serotonin. It is unique among antidepressants because it does not cause sexual dysfunction or weight gain, and actually tends to produce mild weight loss. Bupropion is also approved for smoking cessation under the brand name Zyban and for seasonal affective disorder. It lowers the seizure threshold and is contraindicated in patients with seizure disorders, eating disorders, or those undergoing abrupt alcohol or benzodiazepine withdrawal.