Psychiatric and behavioral side effects of the newer antiepileptic drugs in adults with epilepsy.

OBJECTIVE

Psychiatric/behavioral side effects (PSEs) are common in patients taking antiepileptic drugs (AEDs). The objective of the study described here was to compare the PSE profiles of the newer AEDs.

METHODS

We examined the charts of 1394 adult outpatients seen at the Columbia Comprehensive Epilepsy Center who had taken one of the newer AEDs. We compared the rate of AED-related PSEs in patients newly started on the newer AEDs both before and after controlling for non-AED predictors of PSEs.

RESULTS

Overall, 221 of 1394 (16%) patients experienced PSEs. The average rate of AED-related PSEs for a single AED was 8.4%, with 6.1% resulting in dosage change and 4.3% resulting in AED discontinuation. Significantly fewer PSEs were attributed to gabapentin (n=160, 0.6% incidence, P<0.001) and lamotrigine (n=547, 4.8% incidence, P<0.001), and significantly more PSEs were attributed to levetiracetam (n=521, 15.7% incidence, P<0.001; 8.8% discontinued LEV because of PSEs). Vigabatrin, felbamate, and oxcarbazepine were associated with similarly low rates of PSEs in many analyses but with fewer of patients. Tiagabine was associated with high PSE rates (similar to those for levetiracetam), but was used much less commonly at our center. Intermediate rates of PSEs were attributed to topiramate and zonisamide (both nonsignificant). Psychiatric history was the most significant nondrug predictor of AED-related PSEs (PSEs occurred in 23% of patients with a psychiatric history vs 12% of patients without such a history, P<0.001). The relative rates of AED-related PSEs were similar when controlling for non-AED predictors and when analyzing only patients on monotherapy.

CONCLUSIONS

There are significant differences between the newer AEDs in terms of their PSE profiles. Patients taking levetiracetan experience significantly more PSEs than average, and patients taking gabapentin and lamotrigine experience significantly fewer PSEs. Even with the medication with the highest rate of PSEs (levetiracetam), less than 10% of patients discontinued it because of PSEs. A past psychiatric condition is the most significant nondrug predictor of AED-related PSEs.