Eslicarbazepine Acetate Evaluated for Partial-Onset Seizures

Allison Gandey

October 23, 2009

October 23, 2009 (Baltimore, Maryland) — Results from a new phase 3 study suggest that eslicarbazepine acetate may reduce partial-onset seizures. Presenting here at the 134th annual meeting of the American Neurological Association, investigators say the experimental drug is a safe and effective add-on therapy for difficult-to-treat patients.

"The drug is already available in Europe and is currently under review by the US Food and Drug Administration," study coauthor Mark Versavel, MD, from Sepracor Incorporated, Marlborough, Massachusetts, said during an interview.

Eslicarbazepine acetate has the same mechanism of action as carbamazepine and blocks voltage-gated sodium channels. It is a prodrug that is activated to eslicarbazepine — an active metabolite of oxcarbazepine.

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Dr. Mark Versavel gives an overview of the new drug.

The company-sponsored trial was presented at a poster session. Led by Elinor Ben-Menachem, MD, from Sahlgren University Hospital in Göteborg, Sweden, investigators outlined the randomized double-blind, placebo-controlled, parallel-group study of 325 patients.

The trial ran at 46 centers in 13 countries. The majority of patients were already taking 2 antiepileptic drugs. The most frequent concomitant drugs were carbamazepine, valproic acid, and lamotrigine.

Dr. Versavel said that patients had fewer seizures relative to placebo during the 12-week maintenance period of the trial. He reported the median relative reduction in seizure frequency was highest in the 800- and 1200-mg eslicarbazepine acetate groups. Dr. Versavel said that efficacy results were similar in patients who were already taking carbamazepine, as well as in those who were taking other antiepileptics.

Median Reduction in Seizure Frequency

Treatment Group Relative Reduction (%)
Placebo 5
400 mg 21
800 mg 33
1200 mg 33

Responder Rate of ≥50% Reduction in Seizure Frequency

Treatment Group Rate (%)
Placebo 18
400 mg 20
800 mg 32
1200 mg 35

The most common adverse events were dizziness, somnolence, headache, and nausea. Discontinuation rates resulting from treatment-emergent adverse events were high.

Discontinuation Resulting From Treatment-Emergent Adverse Events

Treatment Group Rate (%)
Placebo 3
400 mg 12.5
800 mg 18.8
1200 mg 26.5
Dr. Daniel Lowenstein

Asked to comment, Daniel Lowenstein, MD, from the University of California–San Francisco, said, "Discontinuation rates of 19 and 27% suggest this drug offers no significant benefit over other available antiepileptics." Dr. Lowenstein is the chair of the scientific program advisory committee for the American Neurological Association. "Eslicarbazepine acetate seems to be very similar to other drugs," he said.

In a recent Medscape Neurology article on current and emerging antiepileptic therapies, Andrew Wilner, MD, a private practitioner in Newport, Rhode Island, wrote about eslicarbazepine acetate. "Although monotherapy is the preferred treatment for people with epilepsy," he noted, "many patients require adjunctive therapy or polytherapy if their seizures do not respond to single-drug treatment."

For a variety of reasons, Dr. Wilner added, antiepileptics are often evaluated as add-on therapies in phase 3 clinical trials, and eslicarbazepine acetate is among them.

Dr. Versavel said that work is underway to evaluate this new drug as monotherapy.

This study was supported by Bial-Portela and Company in Portugal. The poster presentation was supported by Sepracor Incorporated.

American Neurological Association 134th Annual Meeting: Poster M45. Presented October 12, 2009.