"Both weight gain and weight loss have been associated with many antiepileptic drugs," said Wayne Alves, PhD, senior director for clinical research, and retigabine team leader, Valeant Pharmaceuticals International, Costa Mesa, California.

Dr. Alves and colleagues wanted to determine if the investigative compound has effects on patient weight. "Body weight remained stable throughout the long-term extension study," he said.

Retigabine works through a novel mechanism of action, enhancing potassium currents in the brain that impact on the electrical disturbances in the brain that cause seizures.

Dr. Alves and colleagues studied 222 patients in an extended clinical study of retigabine. The mean age of the patients was 36 years and 56.8% of the group were men. The mean body mass index at baseline was 25.3, but ranged from 16.9 to 48.2.

After more than 18 months of treatment the average weight of these patients remained constant at about 73.4 kg at the start of treatment. Among the 94 patients who completed 18 months of treatment, the average weigh was 72.48 kg.

The results allowed the researchers to conclude that treatment with either the 600 mg per day dose of retigabine or with 1200 mg per day was not associated with weight gain, Dr. Alves said.

Several antiepileptic drugs are known to be associated with weight gain, including valproate, carbamazepine, gabapentin, vigabatrin and pregabalin. He also noted that topiramate, felbamate and zonisamide are associated with weight loss, he noted. Phenytoin, lamotrigine and leviteracetam are weight neutral.

While the cohort of patients overall did not show any weight gain, 3 patients did gain weight, and 2 patients dropped out of the study because of weight gain of more than 6.5 kg after 6 months. However, in 1 of those cases, the research team did not believe that the drug was the cause of the weight gain, Dr. Alves said in his poster presentation on December 3^rd.

The study was funded by Valeant.

The congress is a joint meeting of the American Epilepsy Society (AES), the Canadian League Against Epilepsy and the Jamaican chapter of the International League Against Epilepsy.


[Presentation title: Lack of Long-Term Weight Gain with Retigabine in Patients with Partial-Onset Epilepsy. Abstract 2.142]

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