Bupropion SR 100mg Daily: Dose Titration Timeline and Duration of Action
When to Increase Dosage from 100mg SR Daily
You should wait at least 4 days before increasing from 100mg SR to the standard therapeutic dose, though the FDA-approved protocol for bupropion SR typically starts at 150mg daily. 1
Standard Titration Protocol
The FDA label for bupropion XL (which has similar principles) recommends starting at 150mg daily and increasing to 300mg after 4 days, establishing this as the minimum safe interval for dose escalation to minimize seizure risk 1
For bupropion SR specifically, the American Family Physician recommends starting at 150mg once daily for 3 days, then increasing to 150mg twice daily (300mg total) 2
Since you're starting at a sub-therapeutic dose of 100mg SR daily, you should wait at least 4-7 days before increasing to 150mg twice daily (the standard therapeutic dose) 2, 1
Important Timing Considerations
The gradual titration is necessary to minimize seizure risk, which is dose-dependent 2, 1
If you're an older adult or have hepatic/renal impairment, slower titration (increasing by 37.5mg every 3 days) may be more appropriate 2
Duration of Action for 100mg SR
Bupropion SR (sustained-release) has a duration of action requiring twice-daily dosing, with the medication reaching peak levels approximately 3 hours after administration. 3
Pharmacokinetic Profile
Bupropion itself has a half-life of approximately 21 hours, while its primary active metabolite (hydroxybupropion) has a half-life of approximately 20 hours 3
The SR formulation reaches peak concentration (Tmax) at approximately 3 hours, compared to 1.5 hours for immediate-release 3
At steady state, the active metabolite hydroxybupropion reaches concentrations 4-7 fold higher than the parent drug, with an AUC approximately 10-fold greater 3
Practical Duration Implications
A single 100mg SR dose will provide medication coverage for approximately 12 hours, which is why SR formulations are dosed twice daily 2, 3
You should take the second dose before 3 PM to minimize insomnia risk, as bupropion has activating properties 2
Will You Experience a Crash?
No, you should not experience a "crash" with bupropion SR at 100mg daily, as the medication and its active metabolites have long half-lives that provide smooth coverage. 3
Why No Crash Occurs
The combination of bupropion's 21-hour half-life and its active metabolites (with half-lives of 20-37 hours) provides sustained drug levels without abrupt drops 3
The SR formulation is specifically designed for prolonged absorption, with peak levels at 3 hours and gradual decline over 12 hours 3
Even at the end of a dosing interval, significant drug levels remain due to accumulation of long-lived metabolites 3
Clinical Considerations
However, 100mg daily is below the therapeutic dose for depression (standard is 300mg daily in divided doses), so you may not experience robust antidepressant effects at this dose 2, 1
You should assess for adequate therapeutic response after 6-8 weeks at a therapeutic dose before determining if the medication is effective 2
Early monitoring within 1-2 weeks is critical for detecting worsening depression or suicidal ideation, particularly in patients under 24 years of age 2
Key Safety Points
Do not abruptly discontinue bupropion if you've been on it for an extended period; taper from 300mg to 150mg before stopping 1
The maximum dose for SR formulation is 400mg daily (200mg twice daily) to maintain seizure risk below 0.1% 2
Avoid taking the second dose late in the day, as bupropion's activating properties can cause insomnia 2