What are the advantages of using extended release (ER) lamotrigine over regular lamotrigine in patients with seizures or bipolar disorder?

Advantages of Extended-Release Lamotrigine Over Regular Lamotrigine

Extended-release lamotrigine should be used over immediate-release lamotrigine when improved seizure control and reduced adverse effects are priorities, as it provides more stable serum levels with less fluctuation between peak and trough concentrations. 1

Key Benefits of Extended-Release Lamotrigine

1. Improved Seizure Control

• Extended-release lamotrigine (LTG-XR) provides a 46% median reduction in seizure frequency compared to immediate-release formulation (LTG-IR) 1
• Nearly half (47%) of patients experience >50% reduction in seizure frequency when switched from LTG-IR to LTG-XR 1
• Higher trough levels may reduce breakthrough seizures by maintaining more consistent therapeutic concentrations 1

2. Reduced Adverse Effects

• Lower peak concentrations help minimize dose-related adverse effects such as:
  • Dizziness
  • Blurred vision
  • Double vision
  • Unsteadiness 1
• Seven out of 55 patients in a conversion study reported improvement in adverse effects when switching to LTG-XR 1

3. Improved Medication Adherence

• Once-daily dosing with LTG-XR simplifies treatment regimen compared to twice-daily dosing with LTG-IR 2
• Simplified regimen may improve patient adherence, particularly important for epilepsy and bipolar disorder management 2

4. More Stable Serum Concentrations

• LTG-XR minimizes serum concentration fluctuations throughout the day 2
• More consistent drug levels may provide more stable mood and seizure control 1, 2

Clinical Applications

For Epilepsy

• LTG-XR is indicated for patients experiencing:
  • Breakthrough seizures despite adequate LTG-IR dosing
  • Peak-related adverse effects with LTG-IR
  • Adherence issues with twice-daily dosing 1
• Levetiracetam and lamotrigine are preferred first-line options for seizure management due to efficacy and tolerability 3

For Bipolar Disorder

• Lamotrigine is approved for maintenance therapy in adults with bipolar disorder 3
• LTG-XR may provide more stable mood control through consistent serum levels 4, 5
• Particularly beneficial for bipolar depression, where lamotrigine has shown efficacy 4, 5

Important Considerations

Drug Interactions

• Lamotrigine levels are affected by other medications:
  • Decreased by enzyme-inducing anticonvulsants (phenytoin, carbamazepine) 3
  • Increased by valproate 3
• Lamotrigine can affect hormonal contraceptive effectiveness (Category 3 - risks generally outweigh benefits) 3
• Non-enzyme-inducing anticonvulsants like lamotrigine should be preferred when possible to avoid drug interactions 3

Conversion Protocol

When switching from LTG-IR to LTG-XR:

1. Use the same total daily dose initially
2. Monitor serum levels before and after conversion
3. Make dose adjustments based on clinical response and adverse effects
4. Allow adequate time (at least 6 months) to evaluate full benefits 1

Potential Limitations

• Similar safety profile between immediate and extended-release formulations 2
• Risk of serious rash remains a concern with both formulations (requires slow titration) 4, 5
• Higher cost of extended-release formulation may be a barrier for some patients

Conclusion

Extended-release lamotrigine offers significant advantages over immediate-release formulation, particularly for patients with suboptimal seizure control, those experiencing peak-related adverse effects, or those struggling with medication adherence. The more stable serum concentrations provided by LTG-XR translate to better seizure control and improved tolerability, making it a superior option for many patients with epilepsy or bipolar disorder.