Epilepsy Drug With New Method Of Action Is Safe, Effective, Study Shows

"This is good news for the many people with epilepsy who do not respond well to the current available medications," said study author Roger J. Porter, MD, of the University of Pennsylvania in Philadelphia and Fellow of the American Academy of Neurology, who was an employee of Wyeth Pharmaceuticals at the time the study was performed.

The drug retigabine acts by opening potassium channels. The drug is used in people with partial-onset seizures whose seizures are not fully controlled by other drugs. For the study, researchers divided 399 people into four groups. One group received a placebo and the other three groups received different doses of retigabine for 16 weeks. All of the participants were having an average of eight to 10 seizures a month and were also taking one to two other drugs for epilepsy.

Those taking the highest dose of the drug had an average of 35 percent fewer seizures during the study, compared to 13 percent fewer for those taking the placebo. And 33 percent of those taking the highest dosage of the drug had a 50-percent or greater reduction in their seizure frequency.

Side effects included drowsiness, dizziness, confusion, tremor, amnesia, and speech disorders. A total of 79 people withdrew from the study, including 12 people who were receiving the placebo. Porter said the dropout rate when compared with placebo is similar to that seen with other anti-epileptic drugs and is generally due to study design where people are often asked to take high doses in order to maximize benefit.

"Doctors had to increase the patients' dosages on a set schedule for the study," he said. "In regular practice, doctors can decrease the dose, at least temporarily, when a patient has side effects, but that was not possible in this study. Some of the participants might have better tolerated a more flexible dosing schedule."

The study was sponsored and conducted by Wyeth Pharmaceuticals, which developed retigabine. Valeant Pharmaceuticals is the current owner of retigabine and the drug is currently in the late stages of development as an added therapy for partial-onset seizures in adults.