Antiepileptic drug therapy in the United States: a review of clinical studies and unmet needs.

The goal of epilepsy treatment is complete seizure control with minimal adverse drug reactions. Because no drug is entirely free of adverse effects, the clinician must aim for a balance between efficacy and tolerability. In approximately 40% of patients, however, monotherapy with conventional antiepileptic drugs either is not tolerated or does not provide optimal seizure control. Polypharmacy may be necessary in as many as 30% of patients. As clinicians look to new agents that may produce an overall improved quality of life, they must continue to balance efficacy and adverse effects in evaluating the usefulness of the new vs the established drugs.