WASHINGTON -- Low-dose fenfluramine (Fintepla), a Schedule IV controlled substance, was approved to treat seizures associated with Dravet syndrome in patients age 2 and older, the late Thursday.
Dravet syndrome is a rare, life-threatening form of epilepsy often characterized by intractable seizures. It is "a debilitating disease that takes a tremendous toll on both patients and their families," said Billy Dunn, MD, director of the Office of Neuroscience in the FDA's Center for Drug Evaluation and Research.
The FDA's decision was based on two pivotal phase III studies that showed fenfluramine -- the serotonergic agent once used in combination with phentermine ("fen-phen") for weight loss -- bested placebo in reducing convulsive seizure frequency in patients with a mean age of 9.
In both studies, low-dose oral fenfluramine led to significantly greater reductions in seizure frequency than placebo within 3 to 4 weeks. This reduction remained generally consistent throughout the 14-week treatment period. Cardiac monitoring showed children in both trials had no signs of valvulopathy, an before it was pulled off the market in 1997.
Fenfluramine will carry a boxed warning about its association with valvular heart disease and pulmonary arterial hypertension. Patients using the drug must have an echocardiogram before, during, and after treatment.
Because of these risks, fenfluramine will be available only through a restricted drug distribution program under a risk evaluation and mitigation strategy (REMS). The REMS will require prescribers and pharmacies to be certified in the program. Patients must be enrolled and must adhere to required echocardiogram monitoring.
The most common adverse reactions in the trials were decreased appetite, drowsiness and sedation, diarrhea, constipation, abnormal echocardiogram, fatigue, ataxia, balance disorder, gait disturbance, increased blood pressure, drooling, salivary hypersecretion, pyrexia, upper respiratory tract infection, vomiting, decreased weight, risk of falls, and status epilepticus.
The drug is contraindicated in patients with hypersensitivity to fenfluramine and with concomitant use of, or within 14 days of, using monoamine oxidase inhibitors because of increased risk of serotonin syndrome. Fenfluramine will be to certified prescribers, drugmaker Zogenix said.