Epilepsy is one of the most common and disabling chronic neurologic disorders that affects more than 50 million people worldwide. Despite the current of over two dozen antiepileptic drugs (AEDs), about one-third of people with epilepsy fail to achieve complete freedom from seizures with existing medications employed alone or in various combinations. This phenomenon is known as Drug-Resistant Epilepsy (DRE) and represents a major challenge in epilepsy treatment. Tomislav Babić at Worldwide Clinical Trials Inc. explains the challenges of drug development in drug-resistant focal epilepsy.