Maximum Dose of Wellbutrin XL (Bupropion)
The maximum recommended dose of Wellbutrin XL (bupropion extended-release) is 450 mg per day. 1
Dosing Guidelines
Wellbutrin XL follows a specific dosing schedule:
- Starting dose: 150 mg once daily in the morning
- Titration: Can be increased to 300 mg once daily after several days
- Maximum dose: 450 mg once daily 1
The medication should be taken in the morning to minimize the risk of insomnia, which is a common side effect. The extended-release formulation is designed for once-daily dosing, which has been justified in clinical studies with youth and is appropriate for adults as well 2.
Pharmacokinetic Considerations
Bupropion XL has:
- Half-life of approximately 11-14 hours
- Linear pharmacokinetics
- Extensive metabolism to at least six metabolites, some of which may be active 3
- Hydroxybupropion is the primary active metabolite with higher and more sustained levels than bupropion itself 2
Precautions and Dose Adjustments
Dose adjustments are necessary in certain populations:
Hepatic impairment:
- Mild impairment (Child-Pugh score 5-6): Consider reducing dose/frequency
- Moderate to severe impairment (Child-Pugh score 7-15): Maximum 150 mg every other day 4
Renal impairment:
- For GFR <90 mL/min: Consider reduced dose and/or frequency
- Monitor closely for adverse reactions 4
Elderly patients:
- No specific dose adjustment required, but monitor renal function
- May be more sensitive to side effects 4
Side Effects and Risks
Common side effects include:
- Dry mouth (reported in 13% of patients)
- Insomnia
- Headache
- Nausea
- Agitation
The risk of seizures increases with higher doses, which is why the maximum dose is capped at 450 mg daily. In a study of patients who took extra doses of bupropion, seizures occurred in 0.8% of cases, which is twice the rate reported with therapeutic dosing 5.
Clinical Pearls
- Bupropion is activating and may cause rapid improvement in energy levels, making it unsuitable for agitated patients 1
- To minimize insomnia risk, the dose should be taken in the morning 1
- Bupropion should not be used in patients with seizure disorders 1
- The medication is contraindicated with monoamine oxidase inhibitors (MAOIs) within 14 days 6
- Monitor for suicidal ideation, especially during the first month of treatment 6
Conclusion
When prescribing Wellbutrin XL, adhere to the maximum daily dose of 450 mg to minimize the risk of adverse effects, particularly seizures, while maintaining therapeutic efficacy for depression.