Can oxcarbazepine, levetiracetam (Keppra) and lacosamide (Vimpat) be taken together?

Yes, oxcarbazepine, levetiracetam (Keppra), and lacosamide (Vimpat) can be safely taken together.

These three antiepileptic drugs have minimal clinically significant drug interactions with each other and are commonly used in combination for refractory partial-onset seizures. The FDA drug label for Vimpat explicitly states that steady-state plasma concentrations of levetiracetam and oxcarbazepine monohydroxy derivative (MHD) were not affected by concomitant intake of lacosamide 1. This combination represents a rational polytherapy approach using medications with complementary mechanisms of action and favorable pharmacokinetic profiles.

Evidence Supporting This Combination

Drug Interaction Profile

The pharmacokinetic data strongly support the safety of this combination:

• Lacosamide does not affect levetiracetam or oxcarbazepine levels: Clinical studies in patients with partial-onset seizures demonstrated no changes in steady-state concentrations when these drugs were coadministered 1

• Minimal enzyme interactions: Lacosamide does not induce or inhibit major cytochrome P450 enzymes (CYP1A2, 2B6, 2C9, 2C19, 3A4) and has <15% protein binding, making clinically relevant interactions unlikely 1

• Bidirectional effects are minor: While enzyme-inducing drugs like carbamazepine and phenytoin can reduce lacosamide levels by 15-20%, oxcarbazepine causes only small reductions 1. Levetiracetam has minimal risk of adverse drug interactions 2

Clinical Experience

Real-world evidence demonstrates this combination is both effective and well-tolerated:

• In a Russian retrospective study of 181 patients with uncontrolled focal epilepsy, lacosamide was successfully combined with levetiracetam, oxcarbazepine, and other antiepileptics, with 73.2% of patients receiving it alongside two additional drugs. The retention rate was 89.5% at 12 months with only 2.8% discontinuing due to adverse effects 3

• A retrospective study of 56 patients showed lacosamide used with carbamazepine, oxcarbazepine, lamotrigine, valproates, levetiracetam, and topiramate achieved complete seizure cessation in 14.3% and ≥50% reduction in 62.5% of patients 4

Important Caveats and Monitoring

Potential Concerns

While generally safe, be aware of these considerations:

1. One case report suggests lacosamide may lower valproate and levetiracetam levels through an unknown mechanism 5. However, this is a single report and contradicts the larger FDA-approved drug interaction data. Monitor for breakthrough seizures if this combination seems less effective than expected.

2. Dose-dependent side effects can occur with any combination:

   • Common adverse effects include dizziness, diplopia, somnolence, headache, and ataxia 6, 4
   • Neuropsychiatric effects from levetiracetam (irritability, mood changes) may be additive with other CNS depressants 7

3. Sodium channel effects: Both lacosamide and oxcarbazepine affect sodium channels. While not contraindicated, monitor for cardiac conduction abnormalities, particularly PR interval prolongation with lacosamide 6

Monitoring Recommendations

• Baseline and periodic ECGs when using lacosamide, especially in patients with cardiac conduction problems or taking other sodium channel blockers
• Serum sodium levels with oxcarbazepine (hyponatremia risk)
• Renal function for dose adjustments: both levetiracetam and lacosamide require dose reduction in renal impairment 1
• Clinical response and seizure frequency to assess efficacy
• Adverse effects, particularly CNS symptoms (dizziness, somnolence, ataxia)

Dosing Considerations

When combining these medications:

• Start with standard doses and titrate based on clinical response
• Levetiracetam: typically 1,000-3,000 mg/day in divided doses
• Lacosamide: typically 200-400 mg/day in divided doses 6
• Oxcarbazepine: typically 600-2,400 mg/day in divided doses 8
• Consider lower starting doses in elderly patients or those with renal/hepatic impairment

Clinical Context

This triple combination is particularly appropriate for:

• Refractory partial-onset seizures not controlled with monotherapy or dual therapy
• Patients requiring rational polytherapy with drugs having different mechanisms of action
• Situations where enzyme-inducing drugs (phenytoin, carbamazepine, phenobarbital) should be avoided due to drug interactions with other medications 7

The combination leverages levetiracetam's favorable interaction profile 2, lacosamide's sodium channel modulation without enzyme induction 1, and oxcarbazepine's efficacy in partial seizures 9, 8.