With this approval, the drug can be used as monotherapy in people who start treatment for the first time or convert from other antiepileptic drugs (AEDs) to Aptiom.
Aptiom is the only exclusively once-daily non-extended release AED, which can be used alone or in combination with other AEDs to treat partial-onset seizures.
In 2013, the drug was approved by the FDA as adjunctive therapy for partial-onset seizures.
The approval of Aptiom as monotherapy was supported by data from two pivotal Phase III clinical trials (studies 093-045 and 093-046), which met the pre-specified primary endpoint agreed upon with the FDA.
Sunovion is an indirect, wholly owned subsidiary of Sumitomo Dainippon Pharma.
Sunovion Pharmaceuticals executive vice-president and chief medical officer Antony Loebel said: "We are pleased to have achieved FDA approval of a monotherapy indication for Aptiom, based on the results of two identically designed Phase III clinical studies conducted by Sunovion.
"Data from the monotherapy trials, in addition to the data generated from the adjunctive trials, confirm that Aptiom is efficacious and well-tolerated as adjunctive or monotherapy treatment within a daily dose range of 800 to 1,600 milligrams.
"Prescribers now have greater flexibility to optimize clinical response and tolerability when using APTIOM to treat people with partial-onset seizures."
Both the dose-blinded, historical-controlled, multi-center, randomized clinical trials evaluated the safety and efficacy of Aptiom (1,600mg/day or 1,200mg/day) as monotherapy for partial-onset seizures in patients 16 years of age or older whose seizures were not well-controlled with other AEDs.
The company noted that Aptiom administered once-daily was generally well tolerated in both dose strengths.