Oxcarbazepine Safe, Effective in Partial-Onset Seizures

Laurie Barclay, MD

December 12, 2002

Dec. 12, 2002 — At the 56th annual meeting of the American Epilepsy Society, three reports of open-label testing of oxcarbazepine (Trileptal) suggest that the drug is safe and effective in adults and children as monotherapy or in combination with other anti-epileptic drugs (AEDs) for the treatment of partial-onset seizures.

"The ability of an anti-epilepsy medication to gain and maintain control of seizures over an extended period of time is an important characteristic," lead author Tracy A. Glauser, MD, from the Children's Hospital Medical Center in Cincinnati, Ohio, says in a news release. "These data show Trileptal helped reduce seizure frequency over the long term in various epilepsy patient populations."

Dr. Glauser's group conducted a two-year, open-label extension phase of a double-blind, placebo-controlled, parallel-group trial of oxcarbazepine as adjunctive therapy in 233 children, aged 3 to 17 years, who experienced seizures while taking other AEDs.

During the two-year extension, which was completed by 128 patients, 55% of patients had at least a 50% reduction in seizure frequency, 31% had at least a 75% reduction, and 6% were seizure-free. The most frequently reported adverse events, which were mostly mild and transient, were headache in 37%, vomiting in 36%, somnolence in 33%, dizziness in 32%, viral infection in 27%, fever in 24%, and upper respiratory infection in 23%.

The second study, presented by Daniela Minecan, MD, from the University of Michigan in Ann Arbor, was a two-year, open-label extension phase of a trial that examined the safety and efficacy of oxcarbazepine as monotherapy in patients with partial seizures, aged 11 to 66 years. Of 76 patients entering the trial, 35 completed the two-year open-label phase of treatment with oxcarbazepine at a maximum allowable dose of 3,000 mg/day, with other AEDs as clinically indicated.

Seizure frequency decreased by at least 50% in 47% of patients, by at least 75% in 24% of patients, and by 100% in 7% of patients. Of those receiving oxcarbazepine monotherapy, 59% had at least a 50% reduction in seizure frequency, 36% had at least a 75% reduction in seizure frequency, and 10% were seizure-free. Adverse events reported most frequently were dizziness in 46%, headache in 32%, fatigue in 30%, diplopia in 30%, nausea in 26%, abnormal vision in 21%, and somnolence in 21%.

"Oxcarbazepine efficacy was maintained during long-term treatment with no evidence for the development of tolerance," the authors write. "In a clinical practice setting oxcarbazepine is efficacious as monotherapy and combination therapy during long-term treatment in patients with medically refractory partial-onset seizures."

The third study, presented by Steven Schachter, MD, from Harvard Medical School in Boston, Massachusetts, was a two-year, open-label extension phase of a trial of oxcarbazepine monotherapy in 97 patients, aged 11 to 62 years, who were candidates for surgical treatment of partial seizures.

During the 10-day, double-blind treatment phase, 13 of 51 patients treated with oxcarbazepine had a 100% reduction in seizures, and five of these patients remained seizure-free during the two-year open-label extension. Of the 97 patients who entered the open-label phase, 43 completed two years of treatment at a maximum allowable dose of 3,000 mg/day. The most frequently reported adverse events were headache in 61%, dizziness in 58%, diplopia in 45%, fatigue in 41%, nausea in 36%, vomiting in 27%, somnolence in 24%, viral infection in 22%, and abnormal vision in 21%.

"The results indicate that oxcarbazepine maintains its efficacy during long-term management of patients with partial seizures," the authors write.

Because clinically significant hyponatremia has been reported in 2.5% of patients treated with oxcarbazepine in controlled clinical trials, monitoring of serum sodium levels shouldbe considered for patients at risk of hyponatremia.

AES 56th Annual Meeting. Presented Dec. 9 and 10, 2002.

Reviewed by Gary D. Vogin, MD

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