Effective Dosing for Wellbutrin (Bupropion)
The effective dose of Wellbutrin (bupropion) varies by formulation: immediate-release (IR) 300-450 mg/day in 3 divided doses, sustained-release (SR) 300 mg/day in 2 divided doses (150 mg twice daily), and extended-release (XL) 150-300 mg once daily, with a maximum dose of 450 mg/day. 1, 2
Formulations and Standard Dosing
Immediate Release (IR)
- Starting dose: 100-150 mg daily 2
- Titration: Increase gradually to avoid side effects 3
- Maintenance dose: 300-450 mg daily in three divided doses 3
- Maximum dose: 450 mg daily 3
Sustained Release (SR)
- Starting dose: 100-150 mg once daily 2
- Maintenance dose: 100-150 mg twice daily 2
- Typical effective dose: 300 mg/day (150 mg twice daily) 4
- Maximum dose: 400 mg daily (200 mg twice daily) 1
Extended Release (XL/ER)
- Starting dose: 150 mg once daily in the morning 2, 1
- Maintenance dose: 150-300 mg once daily 2
- Maximum dose: 450 mg daily 2
- Note: Once-daily dosing appears to be at least as effective as twice-daily dosing with improved convenience and tolerability 4
Dosing Considerations for Specific Populations
Hepatic Impairment
- For moderate to severe hepatic impairment: Maximum 150 mg daily (XL formulation) or one tablet daily (naltrexone/bupropion combination) 2
- Consider lower doses and slower titration 2
Renal Impairment
- For moderate to severe renal impairment: Reduce total daily dose by half 2
- Avoid in end-stage renal disease 2
Pregnancy
- Bupropion has been used in pregnancy with limited data showing no major increase in congenital malformations 2
- Some studies suggest small absolute increases in cardiovascular malformations with first-trimester exposure, though confounding factors may exist 2
Clinical Efficacy and Monitoring
- Antidepressant effect typically requires 4-8 weeks of treatment at therapeutic doses 2
- For depression: If no response after 8 weeks at maximum tolerated dose, consider alternative treatment 1
- For smoking cessation: Bupropion at 300 mg/day has shown efficacy 2
- For weight management (as naltrexone/bupropion combination): Discontinue if <5% weight loss after 12 weeks at maintenance dose 2
Common Side Effects and Precautions
- Most common side effects: Dry mouth, insomnia, headache, nausea, dizziness, constipation, tremor 5
- Seizure risk: Bupropion lowers seizure threshold; avoid in patients with seizure disorders 2
- Cardiovascular effects: May cause modest increases in blood pressure and heart rate 6
- Drug interactions: Avoid concurrent use with MAOIs; allow 14 days between discontinuing MAOIs and starting bupropion 2
- Psychiatric effects: Monitor for worsening depression, suicidal ideation, or unusual changes in behavior, especially early in treatment 1
Clinical Pearl
When switching between formulations (IR, SR, XL), remember that all three formulations are bioequivalent in terms of systemic exposure to bupropion under steady-state conditions, though the dosing schedule differs 5. This allows for simplified conversion between formulations while maintaining therapeutic effect.