New drugs for persons with epilepsy.

Between 30% and 60% of patients with epilepsy have not achieved adequate control with current medications, and side effects are a significant problem. In the past 2 years, three drugs for epilepsy have been approved. At least six more drugs are in the final stages of development, and there is an active "pipeline." None of the new drugs are panceas, but many have special advantages and meet important specific needs. Felbamate, despite a high incidence of aplastic anemia and hepatic failure, remains useful because of its lack of sedative effects and high efficacy. Gabapentin is remarkable for its favorable side effect profile, lack of interactions, and straightforward kinetics. Lamotrigine is also nonsedating and may be especially useful in generalized epilepsies. Topiramate and vigabatrin are both highly effective, although each is associated with a variety of cognitive or psychiatric side effects that may limit utility. Oxcarbazepine shares the efficacy of carbamazepine, with fewer side effects or drug interactions. Zonisamide seems to be effective and cause mild side effects, although the risk for renal stones indicates a need for cautious use. Tiagabine, like gabapentin, is a mild drug with a favorable side effect profile. New forms of old drugs will make for easier administration; fosphenytoin will increase the safety of parenchymal phenytoin use. The best of the new drugs help, at most, 10% of previously uncontrolled patients to become seizure-free. The development of new drugs remains an important need.