FDA approves GSK/Valeant anti-seizure drug

GlaxoSmithKline (GSK) and Valeant Pharmaceuticals have announced that the US Food and Drug Administration (FDA) has approved Potiga (ezogabine), a potassium channel opener, as adjunctive treatment of partial-onset seizures in patients aged 18 years and older.

The FDA has recommended that the drug is scheduled as a controlled substance under the Controlled Substances Act (CSA). Ezogabine will not be available until the Federal Drug Enforcement Administration (DEA) has completed a final classification of the drug. However, the companies expect that ezogabine will be available in US pharmacies by the end of the year.

"We are so pleased to reach such an important milestone with the US approval of Potiga by the FDA," stated Dr Susan Hall, head of research and development at Valeant. "We believe this product will play a needed role in the management of partial onset seizures in appropriate patients who are uncontrolled on their current medications."

Three controlled clinical studies, involving 1,239 adult patients, were used to establish the efficacy of ezogabine as adjunctive therapy in partial onset seizures. The primary endpoint of the trials was per cent change in seizure frequency from baseline in the double-blind treatment phase.

As urinary retention was reported as an adverse event in about 2 per cent of patients treated with ezogabine as part of the clinical trial process, the FDA has determined that a Risk Evaluation and Mitigation Strategy (REMS) will be necessary for ezogabine, with the goal of informing healthcare professionals of the risk of urinary retention and the symptoms of acute urinary retention.

In three controlled clinical studies, 25 per cent of patients receiving ezogabine), and 11 per cent of patients receiving placebo, discontinued treatment because of treatment-emergent adverse reactions.

The most frequently reported adverse reactions in patients receiving ezogabine vs placebo were dizziness, somnolence, fatigue, confusional state and vertigo.

In the EU, ezogabine is known as retigabine (Trobalt). The drug received marketing authorisation in the EU in March 2011.