Is lamotrigine (Lamictal) 150mg twice daily (BD) a suitable treatment for personality disorder?

Lamotrigine for Personality Disorder: Not Recommended

Lamotrigine 150mg twice daily is not recommended for personality disorder as there is insufficient evidence supporting its efficacy and safety at this dose, and current guidelines do not recommend it as a treatment option for personality disorders.

Evidence Assessment

Lack of Guideline Support

None of the provided guidelines specifically recommend lamotrigine for personality disorders. The most relevant guideline evidence focuses on:

1. Pharmacological treatments for other conditions such as:

   • Bipolar disorder 1
   • Epilepsy 1
   • Major depressive disorder 2

2. For personality disorders specifically, the British Society of Gastroenterology guidelines 3 recommend:

   • Tricyclic antidepressants (TCAs) as second-line treatment
   • Antipsychotics such as sulpiride may be considered as second-line treatment
   • No mention of lamotrigine for personality disorders

Research Evidence on Lamotrigine for Personality Disorder

The research evidence for lamotrigine in personality disorders is limited and contradictory:

1. Early small studies showed some promise:

   • A 2007 retrospective chart review of 13 female patients showed improvement in affective instability 4
   • A 1998 open case series found 50% of patients achieved remission with lamotrigine 5

2. However, the most recent and highest quality evidence is negative:

   • A 2018 randomized controlled trial (RCT) with 276 participants found that "the addition of lamotrigine to the usual care of people with BPD was not found to be clinically effective or provide a cost-effective use of resources" 6

This recent RCT 6 represents the strongest evidence available and does not support lamotrigine use in borderline personality disorder.

Dosing Concerns

The proposed dose of 150mg twice daily (300mg total) is at the upper limit of what has been studied:

• The 2018 RCT used up to 200mg daily (400mg for those on oral contraceptives) 6
• Earlier case studies used doses ranging from 50-300mg daily 7, 4, 5

Alternative Treatment Options

Based on the available guidelines, the following treatments have better evidence for personality disorders:

1. First-line options:

   • Psychotherapy approaches (cognitive behavioral therapy, dialectical behavior therapy)
   • Psychoeducation 1

2. Second-line pharmacological options:

   • Tricyclic antidepressants as gut-brain neuromodulators 3
   • Antipsychotics such as sulpiride (100mg four times daily) or levosulpiride (25mg three times daily) 3

Clinical Implications and Pitfalls

Important Considerations

• Avoid polypharmacy in personality disorders as it's common but lacks evidence
• Be aware that lamotrigine requires slow titration to minimize the risk of serious rash
• The risk of Stevens-Johnson syndrome with lamotrigine is approximately 0.1% 8

Monitoring Requirements

If despite this recommendation you decide to use lamotrigine:

• Start at low doses (25mg) and increase gradually by 25mg weekly
• Monitor closely for rash, especially in the first 8 weeks
• Be aware that women on oral contraceptives may require higher doses due to drug interactions

Conclusion

Based on the most recent high-quality evidence 6, lamotrigine at 150mg twice daily is not recommended for personality disorder. The 2018 RCT found no clinical benefit over placebo, and this represents the strongest available evidence. Consider evidence-based alternatives such as psychotherapy, and if pharmacotherapy is needed, tricyclic antidepressants or specific antipsychotics as recommended in current guidelines.