@@@@Highlights •Lacosamide XR capsules were bioequivalent to lacosamide IR tablets per extent/rate of absorption.•Simulations showed partial adherence scenarios affect lacosamide XR and IR similarly.•Simulations showed lacosamide XR and IR concentrations can be quickly restored after a missed dose.•Simulations showed the best strategy for switching from lacosamide IR to XR was to take morning IR and evening XR doses.•These results support lacosamide XR capsules as a once-daily alternative to lacosamide IR tablets.