Bupropion Mechanism and Clinical Effects

Introduction to Bupropion

Bupropion works primarily as a norepinephrine and dopamine reuptake inhibitor while also blocking nicotinic acetylcholinergic receptors, making it uniquely effective for depression and smoking cessation without the sexual dysfunction and weight gain common to other antidepressants 1, 2

Bupropion acts as an inhibitor of nicotinic acetylcholinergic receptors, which contributes to its smoking cessation efficacy 1, 2

The American College of Cardiology and other guideline societies recommend bupropion for major depressive disorder, as it demonstrates efficacy comparable to SSRIs and tricyclic antidepressants 2, 3
Bupropion is effective for smoking cessation, with a 2014 Cochrane review of 44 trials showing a relative risk of 1.62 (95% CI, 1.49-1.76) for successful cessation 1, 2
The EAGLES trial (n=8,144) showed bupropion achieved superior abstinence rates versus placebo (OR 2.07; 95% CI, 1.75-2.45), with efficacy similar to nicotine patch but less than varenicline 1, 2
Bupropion may be particularly beneficial for patients with comorbid depression who want to quit smoking, addressing both conditions simultaneously 1, 2, 4

Bupropion has a lower rate of sexual dysfunction (approximately 8%) compared to SSRIs like fluoxetine or sertraline, making it the antidepressant with the least sexual side effects 3
Bupropion lowers the seizure threshold with a 0.1% seizure risk at recommended doses, and should be avoided in patients with seizure disorders, brain metastases, eating disorders, or any elevated seizure risk 1, 2, 4, 6
The maximum dose should not exceed 450 mg/day to minimize seizure risk 6

For depression (SR formulation), the recommended dose is 150 mg once daily for 3 days, then increase to 150 mg twice daily (300 mg total) 6
For smoking cessation, the recommended dose is 150 mg twice daily (300 mg total), beginning 1-2 weeks before quit date, for 7-12 weeks 4, 6
The maximum dose is 450 mg/day for XL formulation, 400 mg/day for SR formulation 6

Absolute contraindications for bupropion include seizure disorders or conditions that increase seizure risk, current or recent MAOI use, eating disorders, and abrupt discontinuation of alcohol or sedatives 1, 2, 4, 6
Bupropion inhibits CYP2D6, and should not be combined with tamoxifen, as it may interfere with its metabolism 6
Bupropion is ideal for smokers with depression who want to address both conditions, and may be less likely to provoke mania than serotonergic antidepressants in bipolar depression 1, 2, 4