A patient with bipolar II disorder who is currently taking bupropion (Wellbutrin) 100 mg and lamotrigine 100 mg and is feeling depressed—what evidence‑based next steps should be taken?

Optimize Lamotrigine Dose First

The most evidence-based next step is to increase lamotrigine to a therapeutic dose of 200 mg daily, as the current 100 mg dose is subtherapeutic for bipolar depression. 1

Immediate Action: Titrate Lamotrigine

• Target dose: 200 mg daily (standard therapeutic range for bipolar depression is 200-400 mg)
• Current 100 mg is below the effective threshold demonstrated in clinical trials
• Lamotrigine has compelling evidence as add-on treatment for acute bipolar II depression, with significant reduction in depressive symptoms (SMD -0.30, p=0.004) 1
• Also proven effective for maintenance treatment with lower relapse rates than placebo (RR 0.84, p=0.037) 1

Titration schedule: Increase by 25-50 mg every 1-2 weeks to minimize rash risk, targeting 200 mg initially. Can increase to 400 mg if needed for response.

Critical Concern: Bupropion in Bipolar II

The bupropion (Wellbutrin) 100 mg poses a significant risk and warrants careful monitoring or discontinuation. Despite older literature suggesting lower switch rates, recent meta-analysis shows bupropion carries similar phase-shifting risk to other antidepressants (p=0.952) 2. The FDA label explicitly warns about mood changes including mania, hypomania, and worsening depression 33.

Two Options for Bupropion:

1. Conservative approach (recommended for BD II): Discontinue bupropion and optimize lamotrigine monotherapy first

   • BD II patients may not require antimanic coverage during treatment per clinical discretion 4
   • Reduces polypharmacy and switch risk

2. If continuing bupropion: Monitor weekly for:

   • Irritability, agitation, decreased sleep need
   • Increased energy, impulsivity, racing thoughts
   • Any hypomanic symptoms warrant immediate discontinuation 33

Additional Evidence-Based Adjuncts

If inadequate response after optimizing lamotrigine to 200-400 mg:

Bright Light Therapy (BLT)

• Strong evidence for bipolar depression (SMD=0.43, p=0.03; OR=2.32 for clinical response) 4
• Protocol: 10,000 lux light box for 30 minutes each morning upon awakening
• Safe for BD II without mandatory mood stabilizer coverage (clinician discretion) 4
• Monitor weekly for mood improvement and any hypomanic symptoms
• Increase duration by 15 min/week up to 60 minutes if poor response 4

Quetiapine

• If lamotrigine optimization fails, quetiapine has compelling evidence for bipolar II depression 56
• Consider before adding or continuing antidepressants

Common Pitfalls to Avoid

1. Underdosing lamotrigine: 100 mg is insufficient; most patients require 200-400 mg for antidepressant effect
2. Assuming bupropion is "safe" in bipolar disorder: Recent evidence contradicts this—switch rates are similar to other antidepressants 2
3. Adding multiple agents before optimizing existing ones: Maximize lamotrigine first before layering treatments
4. Ignoring early hypomanic symptoms: Irritability, decreased sleep, increased goal-directed activity require immediate intervention 33

Monitoring Schedule

• Weekly for first month: Mood symptoms, sleep, energy, irritability
• Watch specifically for hypomanic switch with bupropion on board
• Assess lamotrigine response at each dose increase
• If suicidal ideation emerges: discontinue bupropion immediately per FDA guidance 33