Supernus Pharmaceuticals Inc.'s epilepsy drug, Oxtellar XR, was approved by the U.S. Food and Drug Administration as a stand-alone therapy to treat partial-onset seizures in patients aged six to 17 years.

Rockville, Md.-based Supernus' Oxtellar XR was earlier approved as an add-on therapy for partial-onset seizures in adults and in children six to 17 years old.

Epilepsy is a neurological disorder characterized by recurrent seizures. In partial-onset seizures, the electrical disturbance in the brain is limited to one side.

The company plans to launch the drug for the expanded use in the first quarter of 2019.

Supernus intends to bolster its epilepsy portfolio and in September disclosed its plan to acquire privately held company Biscayne Neurotherapeutics, which is developing a treatment for epilepsy.