Carbamazepine 100mg TID Titration Schedule
For adults starting carbamazepine 100mg three times daily (300mg/day total), the FDA-approved titration schedule is to begin with 200mg twice daily (400mg/day) for tablets, then increase at weekly intervals by adding up to 200mg/day using a three or four times daily regimen until optimal response is obtained, with maintenance doses typically 800-1200mg daily. 1
Standard Titration Protocol
Initial Dosing
- Start with 200mg twice daily (400mg/day total) rather than 100mg TID, as this is the FDA-recommended starting dose for adults and children over 12 years 1
- If starting at 100mg TID (300mg/day), this represents a lower-than-standard initial dose that may be appropriate for frail or elderly patients 2
Weekly Titration Steps
- Increase by 200mg/day at weekly intervals using a three or four times daily dosing schedule 1
- The gradual titration over 1-2 weeks minimizes side effects including fatigue, dizziness, ataxia, double vision, nausea, and vomiting 2
- Example schedule: Week 1: 400mg/day → Week 2: 600mg/day → Week 3: 800mg/day → Week 4: 1000mg/day 1
Target Maintenance Dose
- Typical maintenance: 800-1200mg daily for most adults 1
- Maximum dose: 1200mg/day for patients over 15 years (1600mg/day in rare adult cases) 1
- Once seizures are controlled, reduce gradually to minimum effective level 1
Critical Pre-Treatment Requirements
Mandatory Genetic Screening
- HLA-B*15:02 screening must be performed before initiating carbamazepine in patients of Asian descent to assess Stevens-Johnson syndrome risk 3, 4
Baseline Laboratory Testing
- Complete blood count and liver function tests required before starting therapy 4
- These baseline values are essential for monitoring hematologic complications including leukopenia and rare aplastic anemia 2, 5
Therapeutic Monitoring Strategy
Blood Level Timing
- Draw carbamazepine levels 4-6 days after dosing or dose adjustments, not sooner 3, 4
- Drawing levels too early leads to falsely elevated results from transient elevations 3
- Target therapeutic range: 4-8 mcg/mL (15-40 μmol/L) 6, 4, 7
Ongoing Laboratory Monitoring
- Monthly liver function tests for first 3 months, then every 3-6 months if stable 4
- Monitor complete blood count regularly to detect leukopenia (occurs in ~18% of patients) or rare aplastic anemia 5
- Aplastic anemia is most likely to occur within first 3-4 months of therapy 2
Dosing Administration Principles
Timing and Frequency
- Administer with meals to improve tolerability 1
- Use at least twice-daily dosing (preferably three or four times daily) due to carbamazepine's short half-life 2
- This avoids excessively high peak levels that occur with single daily dosing and cause more side effects 2
Alternative Loading Strategy (Emergency Settings Only)
- In emergency department settings for acute seizures, 8 mg/kg oral suspension as single load achieves therapeutic levels within 2 hours with 93% success rate 8, 3
- This loading approach causes adverse effects in 58% of patients (mostly mild/transient) versus standard gradual titration 3
Common Pitfalls to Avoid
Drug Interactions
- Carbamazepine significantly decreases oral contraceptive effectiveness through hepatic enzyme induction—provide contraceptive counseling 6, 4
- Reduces levels of warfarin and corticosteroids 6
- Isoniazid increases carbamazepine levels, risking toxicity 6
- Phenytoin levels may increase when given concurrently 6
Monitoring Errors
- Do not draw levels within first 4-6 days of dose changes—wait for steady state 3, 4
- Do not discontinue for benign transient leukopenia unless severe or symptomatic 2, 5
- Persistent liver enzyme elevation may require discontinuation 6