Is it okay to increase lamotrigine (Lamictal) to 150mg twice a day in a patient with personality disorder who is currently on 100mg twice a day and experiencing benefit?

Increasing Lamotrigine Dosage in Personality Disorder

Yes, it is appropriate to increase lamotrigine from 100mg twice daily to 150mg twice daily in a patient with personality disorder who is experiencing benefit from the current dose. This increase is within the therapeutic range and follows appropriate dosing protocols for mood stabilization in personality disorders.

Dosing Considerations for Lamotrigine in Personality Disorders

Lamotrigine has shown efficacy in treating affective instability and mood symptoms in personality disorders, particularly borderline personality disorder. The dosing approach should follow these guidelines:

• Starting dose is typically low (25-50mg daily) with gradual titration
• Therapeutic range for personality disorders is generally 50-300mg daily
• Dose increases should occur in increments of 25-50mg every 1-2 weeks
• The proposed increase from 200mg to 300mg daily total dose is within the established therapeutic range

Evidence Supporting Lamotrigine in Personality Disorders

Several studies support the use of lamotrigine in personality disorders:

• Open case series have shown robust responses to lamotrigine in borderline personality disorder patients at doses ranging from 75-300mg/day 1
• Retrospective chart reviews found that lamotrigine at doses of 50-200mg/day improved affective instability in borderline personality disorder patients 2
• Clinical research indicates that the general effective dose range for lamotrigine in affective disorders is 50-300mg daily 3

Safety Considerations

When increasing the lamotrigine dose, monitor for:

1. Skin rash - this is the most serious potential adverse effect
2. Headache, dizziness, or somnolence
3. Gastrointestinal symptoms
4. Changes in mood or behavior

The risk of serious rash is highest during initial titration, not during later dose increases after the patient has already tolerated the medication, making this increase relatively safe from that perspective.

Titration Protocol

For the proposed increase:

• Increase from 100mg twice daily to 150mg twice daily
• Consider a step-wise approach: increase to 100mg morning/150mg evening for 1 week before reaching 150mg twice daily
• Monitor for side effects during the titration period
• Assess therapeutic response after 2-4 weeks at the new dose

Monitoring Recommendations

After increasing the dose:

• Evaluate therapeutic response using standardized measures if available
• Monitor for adverse effects at follow-up visits
• Consider serum level monitoring if there are concerns about adherence or toxicity
• Assess for any changes in other medications that might interact with lamotrigine

Common Pitfalls to Avoid

1. Increasing the dose too rapidly (not applicable in this case as patient is already established on lamotrigine)
2. Failing to monitor for adverse effects
3. Not recognizing drug interactions (particularly with oral contraceptives which can lower lamotrigine levels)
4. Overlooking the need for regular follow-up to assess efficacy

The evidence supports that lamotrigine can be an effective treatment for affective instability in personality disorders, and increasing the dose in a patient already showing benefit is a reasonable approach to optimize therapeutic outcomes.