PHARMACOLOGICAL INTERVENTION AND TREATMENT OF CHILDHOOD SEIZURE DISORDERS - RELATIVE EFFICACY AND SAFETY OF ANTIEPILEPTIC DRUGS

Four antiepileptic drugs (AEDs) represent > 90% of all AEDs prescribed in the United States. The efficacies of the available AEDs are surprisingly similar and far from complete, and none is entirely safe. Thus, the incidence of side effects is often the determining factor in the choice of AED. Clinical decisions about which AED to select should be made on the basis of the combination of efficacy and toxicity, expressed as a protective or therapeutic index (TI). Efficacy seldom comes without some degree of toxicity, whereas toxicity can occur in the absence of any efficacy. As the dose of the AED increases, efficacy can reach a plateau but toxicity does not. Complete seizure control should not be the final goal of epilepsy treatment; optimal AED therapy is equal to the highest possible TI, not necessarily to maximal seizure control. Each AED has a different TI, and each has a different TI in every patient. This is confounded further when combinations of AED are prescribed.