Ezogabine (Potiga): Oral potassium channel opener indicated as adjunctive treatment of partial-onset seizures in patients aged 18 years and older

Epilepsy is often difficult to manage, with one-third of patients failing to achieve satisfactory seizure control. Consequently, multiple antiepileptic drugs are frequently used in combination in an attempt to reduce seizure frequency. On June 10, 2011, FDA approved the oral potassium channel opener ezogabine for use as an add-on medication to treat partial-onset seizures associated with epilepsy in adults.

Efficacy. The efficacy of ezogabine as adjunctive therapy in partial-onset seizures was established in 3 multicenter, randomized, double-blind, placebo-controlled studies (n=1,239) that monitored seizure frequency. All 3 clinical studies enrolled patients suffering from partial-onset seizures, were taking at least 1 antiepileptic drug, and were inadequately controlled. In each trial, patients were randomly assigned to 600, 900, or 1,200 mg per day maintenance doses of ezogabine or placebo. In each of the 3 studies, the median percent reduction in 28-day seizure frequencies in patients receiving ezogabine 600, 900, and 1,200 mg per day were statistically greater than placebo.

Safety. In clinical trials, the most common adverse events (occurring >4% and approximately twice the placebo rate) were dizziness, somnolence, fatigue, confusional state, vertigo, tremors, abnormal coordination, diplopia, disturbance in attention, memory impairment, asthenia, blurred vision, gait disturbance, aphasia, dysarthria, and balance disorder. In most cases the reactions were of mild or moderate intensity. Other adverse reactions (occurring in <2% of patients) were increased appetite, hallucinations, myoclonus, peripheral edema, hypokinesia, dry mouth, dysphagia, hyperhydrosis, urinary retention (typically in the first 6 months of treatment), malaise, and increased liver enzymes. Adverse reactions were found to be directly correlated to dose. Like other antiepileptic drugs, ezogabine may cause suicidal thoughts or actions in a small number of people.