The occurrence, management and outcome of antiepileptic drug side effects in 767 patients.

This study reports the nature of adverse drug reactions (ADR) occurring in 767 epilepsy clinic patients (adults and children), the drugs most commonly involved, how they were managed and the outcome of such management. One hundred and thirty four patients were found to have 155 separate ADRs. The majority appeared to be pharmacodynamic in nature, although 21 were clearly pharmacokinetic in origin and four due to drug interactions. The antiepileptic drugs (AED) perceived to be causative, in order of frequency were phenytoin, sodium valproate, carbamazepine, clonazepam, barbiturates, vigabatrin and clobazam. Management most often involved withdrawing the offending drug(s), usually replacing them with another AED. Of the 155 ADRs, 40.6% resolved totally, 27.7% showed a marked improvement, 16.1% improved, 14.8% did not change and one patient deteriorated. This study emphasizes the need to be vigilant for ADRs and demonstrates that their management is essentially clinical with some 85% of patients experiencing benefit.