Concurrent Use of Trileptal and Lamictal
Yes, it is safe to take Trileptal (oxcarbazepine) and Lamictal (lamotrigine) together—these medications do not have clinically significant pharmacokinetic interactions and are commonly combined for both epilepsy and bipolar disorder management. 1, 2
Pharmacokinetic Evidence
No dose adjustments are required when combining these medications. A dedicated pharmacokinetic study in healthy volunteers demonstrated that:
- Lamotrigine's AUC and maximum concentration (Cmax) were not significantly affected by oxcarbazepine co-therapy 2
- Oxcarbazepine's active metabolite (MHD) levels were similarly unaffected by lamotrigine 2
- Neither drug interferes with the other's metabolism or elimination 2
This lack of interaction is explained by their different metabolic pathways—lamotrigine primarily undergoes glucuronidation, while oxcarbazepine is metabolized to its active monohydroxy derivative without significant enzyme induction or inhibition that would affect lamotrigine. 3
Clinical Applications
This combination is used in two main contexts:
For Epilepsy:
- Both drugs are effective for partial onset seizures 4
- Lamotrigine, carbamazepine (oxcarbazepine's close relative), and oxcarbazepine provide optimal seizure control for partial seizures 4
- The combination may be appropriate for refractory cases requiring polytherapy 5
For Bipolar Disorder:
- Lamotrigine is FDA-approved for maintenance therapy in bipolar disorder 6
- Atypical antipsychotics and mood stabilizers are commonly combined with lamotrigine 1
- The American Academy of Child and Adolescent Psychiatry supports combination therapy when clinically indicated, though care should be taken to avoid unnecessary polypharmacy 6
Important Safety Considerations
Increased frequency of adverse effects occurs with combination therapy, though these are typically manageable: 2
- Headache, dizziness, nausea, and somnolence occur more frequently with the combination than with either drug alone 2
- These are dose-dependent central nervous system effects rather than dangerous interactions 2
- No significant changes in laboratory parameters, vital signs, or cardiac function were observed 2
Special population considerations:
- Women of childbearing age: Oxcarbazepine can reduce oral contraceptive efficacy—alternative or additional contraceptive methods should be used 6, 3
- Elderly patients: May experience increased sensitivity to CNS adverse effects; start with lower doses and titrate slowly 3
- Patients with mental health comorbidities: Monitor for behavioral changes, though this is less concerning with lamotrigine and oxcarbazepine compared to GABA-ergic drugs 3
Practical Management
When prescribing this combination:
- Titrate each medication to therapeutic effect independently 2
- Monitor for additive CNS side effects (dizziness, somnolence) particularly during dose escalation 2
- Counsel patients about increased but manageable side effect burden 2
- Ensure adequate contraception in women due to oxcarbazepine's effect on hormonal contraceptives 6
- No routine therapeutic drug monitoring is required based on the interaction profile, though monitoring may be indicated for other clinical reasons 2