What to prescribe for a patient with mood instability and seizures on Vimpat (lacosamide) and Keppra (levetiracetam)?

Management of Mood Instability in a Patient with Seizures on Vimpat and Keppra

For a patient with mood instability and seizures on Vimpat (lacosamide) and Keppra (levetiracetam), lamotrigine is the recommended addition for mood stabilization while maintaining seizure control.

Understanding the Current Medication Profile

The patient is currently on two antiepileptic medications:

1. Lacosamide (Vimpat)

   • Mechanism: Selective slow inactivation of voltage-gated sodium channels 1
   • May have positive effects on mood and anxiety symptoms 2
   • Well-tolerated in patients with focal seizures 1

2. Levetiracetam (Keppra)

   • Commonly used first-line agent for seizure control 1
   • Associated with psychiatric side effects including mood disturbances 1
   • May actually be contributing to the patient's mood instability

Assessment of the Clinical Situation

Potential Causes of Mood Instability

1. Medication-induced mood changes

   • Levetiracetam is known to cause psychiatric side effects including irritability, mood swings, and depression 1
   • These side effects are a "concern" according to guidelines 1

2. Underlying mood disorder comorbid with epilepsy

   • Mood disorders frequently co-occur with epilepsy
   • The seizure disorder itself may contribute to mood instability

Treatment Recommendations

Option 1: Add a Mood Stabilizer

Lamotrigine is the optimal choice for several reasons:

• Specifically recommended by guidelines for seizure control with good mood-stabilizing properties 1
• Has "good antiseizure activity" according to neuro-oncology guidelines 1
• Non-enzyme-inducing, avoiding drug interactions with current medications 1
• Effective for both focal and generalized seizures 3

Option 2: Consider Medication Adjustment

If lamotrigine is not suitable:

1. Valproic acid

   • Guidelines note it "still has a firm place in some centers" 1
   • Good efficacy and overall tolerability 1
   • However, contraindicated in women who may become pregnant 1
   • Can be used as adjunctive therapy for seizure control 1

2. Replace levetiracetam

   • If levetiracetam is suspected to be causing mood instability, consider replacing it with another antiepileptic with better psychiatric profile
   • Lacosamide could be maintained as it may have positive effects on mood 2

Implementation Plan

1. Add lamotrigine:

   • Start at low dose and titrate slowly (over several weeks) to reach therapeutic levels 1
   • Initial dose: 25mg daily, with gradual titration to minimize risk of rash
   • Target dose: 100-200mg twice daily (individualized based on response)

2. Monitor closely:

   • Assess for improvement in mood symptoms
   • Continue to monitor seizure control
   • Watch for potential side effects, particularly rash (which can be serious with lamotrigine)

3. If inadequate response:

   • Consider valproic acid as an alternative mood stabilizer
   • Or consider transitioning from levetiracetam to another antiepileptic with better psychiatric profile

Important Considerations and Pitfalls

• Avoid enzyme-inducing antiepileptics (phenytoin, phenobarbital, carbamazepine) as they have significant drug interactions and are no longer recommended as first-choice agents 1
• Monitor for psychiatric side effects of all antiepileptic medications, particularly with levetiracetam
• Beware of potential serious rash with lamotrigine, especially if titrated too quickly
• For female patients of childbearing potential, consider teratogenicity risks with valproic acid 3

Lamotrigine has demonstrated efficacy for both seizure control and mood stabilization, making it the optimal choice for addressing both conditions in this patient.