What are the recommended doses of bupropion (Wellbutrin) for the sustained‑release, extended‑release, and immediate‑release formulations in adults?

Wellbutrin (Bupropion) Dosing

For smoking cessation, start bupropion at 150 mg once daily for 3 days, then increase to 150 mg twice daily (maximum 300 mg/day) for 7-12 weeks, initiating 1-2 weeks before the quit date 1.

Formulation-Specific Dosing

Sustained-Release (SR) Formulation

For depression:

• Initial dose: 150 mg once daily in the morning
• Titration: After 3-4 days, increase to 150 mg twice daily if tolerated
• Maximum dose: 200 mg twice daily (400 mg/day total)
• Timing: Give second dose before 3 PM to minimize insomnia 2

For depression treatment, both 150 mg/day and 300 mg/day have demonstrated efficacy, with 300 mg/day showing superior response rates 3.

Extended-Release (XL) Formulation

For depression:

• Initial dose: 150 mg once daily in the morning
• Titration: May increase to 300 mg once daily after several days
• Maximum dose: 450 mg once daily
• Key advantage: Once-daily dosing improves convenience and compliance 4, 5

The XL formulation is bioequivalent to SR but offers simplified dosing with similar efficacy and tolerability 5, 6.

Immediate-Release (IR) Formulation

For depression:

• Initial dose: 37.5-100 mg in the morning
• Titration: Increase by 37.5 mg every 3 days as tolerated
• Target dose: 100 mg three times daily
• Maximum dose: 150 mg three times daily (450 mg/day total) 2, 7

Special Clinical Situations

Combination Therapy (Naltrexone-Bupropion ER for Obesity)

For weight management:

• Week 1: One tablet (8 mg naltrexone/90 mg bupropion) daily in the morning
• Week 2: One tablet twice daily
• Week 3: Two tablets in the morning, one in the afternoon
• Week 4 onward: Two tablets twice daily (maintenance dose = 32 mg naltrexone/360 mg bupropion daily)
• Important: Take second dose earlier in the day to avoid insomnia 8

Neuropathic Pain (as Coanalgesic)

Starting dose: 100-150 mg daily Target dose: 150-450 mg daily 9

Dose Adjustments

Renal Impairment

• Moderate to severe impairment: Reduce total daily dose by 50%
• End-stage renal disease: Avoid use 8

Hepatic Impairment

• Moderate to severe impairment: Maximum 150 mg daily (or one tablet daily for combination product) 8

Critical Safety Considerations

Seizure Risk

The dose-related seizure risk is the most important safety concern. The incidence is approximately 0.1% at 300 mg/day but increases nearly 10-fold between 450-600 mg/day 4.

Contraindications for bupropion:

• Seizure disorder or history of seizures
• Eating disorders (anorexia/bulimia)
• Abrupt discontinuation of alcohol, benzodiazepines, or antiepileptics
• Brain metastases or CNS tumors
• Concurrent MAO inhibitor use (within 14 days) 1, 4

Neuropsychiatric Monitoring

Monitor for worsening depression, suicidal ideation, agitation, or behavioral changes, particularly in patients under 24 years old. However, recent large trials (EAGLES study) found no significant increase in neuropsychiatric adverse events compared to placebo 1, 10.

Hypertension

Monitor blood pressure before and during treatment. Risk increases with concomitant nicotine replacement therapy (6.1% vs 2.5% with bupropion alone) 4.

Common Pitfalls to Avoid

1. Never exceed 150 mg per single dose for SR formulation or 300 mg for XL formulation to minimize seizure risk
2. Avoid late-day dosing - give second dose before 3 PM to prevent insomnia
3. Do not use in patients requiring opioid therapy when prescribing naltrexone-bupropion combination
4. Gradual titration is essential - rapid dose escalation increases adverse effects and seizure risk
5. Screen for eating disorders and seizure history before initiating treatment

Treatment Duration

• Smoking cessation: 7-12 weeks initially; may extend to 6-12 months for relapse prevention 1
• Depression: Minimum 4-8 weeks for adequate therapeutic trial; reassess need after 9 months 2
• Weight management: Discontinue if <5% weight loss after 12 weeks at maintenance dose 8