Wellbutrin Initiating Dose
Start bupropion at 150 mg once daily in the morning for the first 3 days, then increase to 150 mg twice daily (300 mg/day total) if tolerated. 1, 2
Standard Dosing Algorithm
The most recent NCCN smoking cessation guidelines 1 and FDA labeling 3 provide consistent dosing recommendations:
Initial Titration Schedule:
- Days 1-3: 150 mg orally once daily in the morning
- Day 4 onward: 150 mg orally twice daily (total 300 mg/day)
- Maximum dose: 300 mg per day
This titration schedule applies across multiple indications including depression 1, 2, smoking cessation 1, 2, and weight management (when combined with naltrexone) 4.
Key Clinical Considerations
Timing of Second Dose
Give the second 150 mg dose before 3 PM to minimize insomnia risk 5. The medication is activating rather than sedating, so evening dosing can interfere with sleep.
Alternative Starting Dose for Specific Populations
For elderly patients or those with tolerability concerns, consider starting at 37.5 mg every morning, then increase by 37.5 mg every 3 days up to the target of 150 mg twice daily 5. However, the standard 150 mg starting dose is generally well-tolerated in most adults.
Dose Adjustments for Organ Dysfunction
- Moderate to severe renal impairment: Reduce total daily dose by 50% 4
- End-stage renal disease: Avoid use 4
- Moderate to severe hepatic impairment: Do not exceed 150 mg daily total 4
Critical Safety Warnings
Absolute Contraindications
Do not prescribe bupropion in patients with:
- Seizure disorders or conditions that lower seizure threshold (stroke, brain metastases, eating disorders) 1
- Current use of MAO inhibitors or within 14 days of discontinuation 1
- Concurrent tamoxifen use 1
- Closed-angle glaucoma 1
Seizure Risk
The seizure risk is dose-dependent. At doses ≤300 mg/day with proper divided dosing, the seizure rate is comparable to other antidepressants 6. Never exceed 300 mg per day total dose to minimize seizure risk 1.
Efficacy Timeline
Clinical trials demonstrate that bupropion 300 mg/day is effective for depression 3, 7, with some patients showing response as early as 2 weeks 8. The FDA label confirms efficacy at 300 mg/day, though one trial showed benefit only at 450 mg/day 3. However, given seizure concerns, start at 300 mg/day and only consider higher doses in specialized settings with careful monitoring.
Therapeutic Drug Monitoring
For patients with inadequate response at standard doses, consider measuring serum 4-hydroxybupropion levels (the major active metabolite). Target levels above 860 ng/mL are associated with marked improvement 9. Women may achieve higher serum levels than men at equivalent doses due to CYP2B6 differences 9.
Common Pitfalls to Avoid
- Don't start at full dose: The 3-day titration at 150 mg once daily reduces initial side effects
- Don't dose late in the day: This causes insomnia due to the activating properties
- Don't ignore seizure risk factors: Screen carefully for history of seizures, eating disorders, or brain lesions
- Don't combine with opioids if using naltrexone-bupropion: The naltrexone component will block opioid effects 4