What is the starting dose of Wellbutrin (bupropion)?

Starting Dose of Wellbutrin (Bupropion)

For major depressive disorder, start bupropion sustained-release (SR) at 150 mg once daily in the morning for 3 days, then increase to 150 mg twice daily (300 mg total) if tolerated. 1 For the extended-release (XL) formulation, the FDA-approved starting dose is 150 mg once daily in the morning, which may be increased after 4 days to the target dose of 300 mg once daily. 2

Standard Dosing by Formulation

Bupropion SR (Sustained-Release)

• Initial dose: 150 mg once daily in the morning for 3 days 1
• Target dose: 150 mg twice daily (300 mg total daily) starting on day 4 1
• Maximum dose: 400 mg per day 1
• Timing: Give the second dose before 3 PM to minimize insomnia risk 3, 1

Bupropion XL (Extended-Release)

• Initial dose: 150 mg once daily in the morning 2
• Target dose: 300 mg once daily after 4 days 2
• Maximum dose: 450 mg per day 1
• Administration: Take once daily in the morning, with or without food 2

Special Population Dosing Adjustments

Older Adults (≥65 Years)

Start at approximately 50% of the standard adult dose to reduce adverse reactions. 1 The recommended initial dose is 37.5 mg every morning, then increase by 37.5 mg every 3 days as tolerated, with a maximum of 150 mg twice daily (300 mg total). 3, 1 This gradual titration minimizes risks of agitation, seizures, and cardiovascular effects in elderly patients. 1

Hepatic Impairment

• Moderate to severe impairment (Child-Pugh 7–15): Maximum dose is 150 mg every other day 2, 1
• Mild impairment (Child-Pugh 5–6): Consider reducing dose and/or frequency 2

Renal Impairment

• Moderate to severe (GFR <90 mL/min): Reduce total daily dose by 50% (e.g., 150 mg daily instead of 300 mg) 1
• End-stage renal disease: Avoid bupropion entirely, as metabolites accumulate and dialysis does not effectively clear them 1

Critical Safety Considerations Before Initiating

Absolute Contraindications

• Seizure disorders or conditions predisposing to seizures (head trauma, brain tumor, stroke) 3, 1
• Current or recent MAOI use (within 14 days) 2
• Eating disorders (bulimia, anorexia nervosa) due to increased seizure risk 1
• Abrupt discontinuation of alcohol, benzodiazepines, or antiepileptic drugs 1, 4
• Uncontrolled hypertension 1

Baseline Screening Required

• Blood pressure and heart rate: Bupropion can elevate both parameters, requiring periodic monitoring especially in the first 12 weeks 1
• Suicidal ideation assessment: All patients, particularly those under 24 years, require close monitoring for emergent suicidal thoughts during the first 1–2 months 2, 1
• Seizure risk factors: Confirm absence of conditions that lower seizure threshold 1

Titration Strategy and Timing

The gradual dose escalation is mandatory to minimize seizure risk, which is approximately 0.1% (1 in 1,000) at the standard 300 mg/day dose. 1 Doses above 450 mg/day markedly increase seizure risk and should never be exceeded. 1

For patients requiring slower titration (e.g., elderly, multiple medications, anxiety about side effects), start at 37.5 mg once daily and increase by 37.5 mg every 3 days. 3, 1 This approach allows careful assessment of tolerability while building toward therapeutic levels.

Expected Timeline for Clinical Response

• Energy improvement: May occur within the first few weeks, as bupropion has activating properties 1
• Full antidepressant effect: Requires 6–8 weeks at therapeutic doses 1
• Response assessment: Do not modify treatment before completing a full 6–8 week trial at adequate doses 1

Common Pitfalls to Avoid

• Dosing too late in the day: The second SR dose must be given before 3 PM to prevent insomnia 3, 1
• Premature dose escalation: Increasing doses faster than recommended raises seizure risk 2
• Using in agitated patients: Bupropion's activating properties can worsen agitation; it should be avoided in highly agitated individuals 3
• Skipping baseline blood pressure measurement: Uncontrolled hypertension is a contraindication that must be identified before starting therapy 1
• Inadequate monitoring in young adults: Patients under 24 years carry an FDA black-box warning for increased suicidal thoughts and require intensive monitoring during weeks 1–2 2, 1

Formulation-Specific Considerations

Bupropion SR requires twice-daily dosing, while XL allows once-daily administration. 1 The SR formulation uses a wax-matrix vehicle for gradual release, with peak plasma concentrations at approximately 3 hours. 1 The XL formulation has a lower peak concentration and longer time to peak compared to SR, justifying once-daily dosing. 1 Both formulations are bioequivalent in total drug exposure but differ in their release profiles. 1

When switching between formulations or from brand to generic, monitor closely for loss of antidepressant effect, as historical bioequivalence issues have been reported with some generic SR formulations. 1