The U.S. Food and Drug Administration (FDA) has refused to fully review Zogenix’s marketing application for its seizure drug, Fintepla (ZX008, low-dose fenfluramine).

The liquid solution, which is a low-dose formulation of the appetite suppressant fenfluramine, is developed to treat seizures caused by Dravet syndrome, a rare form of childhood epilepsy.

The submission was initially based on data from two pivotal Phase III trials and an open-label extension study in Dravet syndrome, which demonstrated highly significant, safe and durable seizure reduction.

The studies found that children and young adults treated with the drug achieved a 54% greater reduction in mean monthly convulsive seizures, paired with a median longest seizure-free interval of 22 days, as opposed to 13 days for patients in the placebo group.

The company stated that they did not submit certain non-clinical studies to allow the FDA to assess chronic administration of the drug, as well as an incorrect version of a clinical dataset, which prevented the regulator from completing its review.

Due to this, the FDA has not asked for more clinical data showing efficacy, nor did it request additional studies to demonstrate the drug’s safety.

Dravet syndrome is an intractable and difficult-to-treat epilepsy that begins in infancy and is associated with frequent, severe, and potentially life-threatening seizures, developmental delay, and cognitive impairment.