GlaxoSmithKline announced today that the U.S. Food and Drug Administration has approved Lamictal®XR™ (lamotrigine) Extended-Release Tablets as once-a-day, add-on therapy for epilepsy in patients ages 13 years and older with primary generalized tonic-clonic seizures.  This is an expanded label, as Lamictal XR is approved for partial onset seizures (with or without secondary generalization) for patients [...]