Seizures associated with therapeutic doses of venlafaxine and trimipramine

OBJECTIVE: To report a patient having a first-time seizure after receiving venlafaxine and trimipramine for depression. CASE SUMMARY: A 25-year-old white woman with chronic depression was treated with venlafaxine 150 mg/d and trimipramine 50 mg/d. Eleven days after increase of the trimipramine dosage to 100 mg/d, she was hospitalized because of seizures suggesting a secondary generalized grand-mal episode. The electroencephalogram showed a pathologic pattern with several generalized epileptiform discharges. Because of suspected drug-induced seizures, both antidepressants were stopped. After antidepressant drug cessation, the patient was symptom free and had no further seizure episodes within the following 12 months of follow-up. No other potential cause for the seizure episode could be identified. DISCUSSION: Both venlafaxine and trimipramine have been associated with seizures, mainly after overdose. Venlafaxine-associated seizures at therapeutic doses have not been reported in the literature. We hypothesize that a pharmacodynamic or pharmacokinetic drug interaction between venlafaxine and trimipramine involving the CYP2D6 isoenzyme may have played a role in inducing the seizures. CONCLUSIONS: Clinicians should be aware of the proepileptogenic effect of venlafaxine and trimipramine at therapeutic doses and that this combination may eventually increase the risk of seizures.