The FDA has approved the drug Potiga (ezogabine) as an add-on drug to treat partial seizures caused by epilepsy. Partial seizures affect only a limited area of the brain but can spread to other parts of the brain and cause a variety of symptoms, including spasms, unusual behavior, convulsions, and loss of consciousness.
It's the first drug in a new class of seizure medications design for epilepsy treatment known as neuronal potassium channel blockers. Although the exact mechanism of these drugs is not clear, they are believed to control seizures by stabilizing potassium channels in the brain affected by epilepsy.
"About one-third of people with epilepsy do not achieve satisfactory seizure control from treatments they are currently using," says Russell Katz, MD, director of the Division of Neurology Products in the FDA's Center for Drug Evaluation and Research, in a news release. "It is important to have a variety of treatment options available for patients with epilepsy."
The FDA's approval was based on the results of three clinical trials involving more than 1,000 adults. These studies showed Potiga reduced seizure frequency by about 30%-40% in those who responded to the drug.
The most common side effects caused by Potiga in clinical trials included dizziness, fatigue, confusion, tremor, problems with coordination, double vision, problems paying attention, memory problems, and lack of strength.
In addition, Potiga can cause problems emptying the bladder, a problem known as urinary retention that is common among seizure medications.
Overall, 25% of people receiving Potiga in clinical trials discontinued treatment due to negative side effects compared with 11% of those who received the placebo.
As with other seizure medications and epilepsy treatments, the FDA warns that Potiga may cause psychological symptoms, such as confusion, hallucinations, and suicidal thoughts in a small number of people. People who experience these symptoms should contact their health care provider immediately.
Potiga is expected to become available in U.S. pharmacies as a controlled substance by the end of 2011. The drug was developed by Valeant Pharmaceuticals North America of Durham, N.C., and will be distributed by GlaxoSmithKline of Research Triangle Park, N.C.
Potiga is known as Trobalt (retigabine) outside the U.S. and was approved for use by the European Union in March.