Can I switch a patient from Bupropion (BID - twice a day) 100mg to 300mg extended release?

Switching from Bupropion 100mg BID to 300mg Extended Release

Yes, you can switch directly from Bupropion 100mg twice daily (200mg total daily dose) to 300mg extended release once daily, as the formulations are bioequivalent and the FDA labeling explicitly supports this conversion when giving the same total daily dose when possible. 1

Direct Conversion Protocol

• Switch the patient directly to 300mg XL once daily in the morning 1
• The FDA labeling states: "When switching patients from WELLBUTRIN tablets (bupropion hydrochloride tablets) to bupropion hydrochloride extended-release tablets (XL) or from WELLBUTRIN SR sustained-release tablets to bupropion hydrochloride extended-release tablets (XL), give the same total daily dose when possible" 1
• While your patient is currently on 200mg total daily (100mg BID), the 300mg XL formulation represents the standard therapeutic target dose for both depression and smoking cessation 2, 1

Pharmacokinetic Rationale

• The XL formulation reaches peak concentration (Tmax) at approximately 5 hours versus 3 hours for SR formulation, providing more gradual absorption throughout the day 3
• All three formulations (IR, SR, and XL) are bioequivalent, meaning they deliver the same amount of active drug despite different release profiles 3
• Bupropion has a half-life of approximately 21 hours, and its primary active metabolite hydroxybupropion has a half-life of approximately 20 hours, supporting once-daily dosing with XL formulation 3

Administration Instructions

• Administer the 300mg XL tablet once daily in the morning 2, 1
• The tablet must be swallowed whole and not crushed, divided, or chewed 1
• Can be taken with or without food 1

Safety Monitoring After Switch

• Monitor for insomnia risk, which is the most common side effect and occurs more frequently than placebo 4, 5
• Watch for dry mouth, the only other adverse effect significantly more common than placebo 4, 5
• Monitor blood pressure and heart rate, particularly during the first 12 weeks, as bupropion can cause elevations in both 2
• Assess for neuropsychiatric adverse effects, especially in patients younger than 24 years 2

Critical Safety Considerations

• The maximum dose of 300mg daily minimizes seizure risk to approximately 0.1% 4, 6, 5
• Do not exceed 300mg daily for smoking cessation or 450mg daily for depression (though 300mg is the typical target) 2, 1
• Confirm the patient has no history of seizure disorder, eating disorders (bulimia or anorexia nervosa), or recent abrupt discontinuation of alcohol, benzodiazepines, barbiturates, or antiepileptic drugs, as these are absolute contraindications 1

Dose Adjustments for Special Populations

• For moderate to severe hepatic impairment (Child-Pugh 7-15), maximum dose is 150mg every other day 1
• For renal impairment (GFR <90 mL/min), reduce dose and/or frequency by approximately 50% 2, 1
• For older adults, if starting fresh, begin at 37.5mg daily and titrate by 37.5mg every 3 days, but direct conversion from established therapy is appropriate 2

Expected Efficacy

• The 300mg daily dose is directly related to anti-smoking efficacy and represents the optimal dose for the majority of patients 7
• For depression, allow 6-8 weeks at adequate dose before determining treatment response 2
• For smoking cessation, efficacy should be assessed after 7-12 weeks of treatment 2