The objective of this study was to investigate the effect of switching anti-epileptic drugs (AEDs) to once a day regimen in patients with drug-resistant epilepsy with poor adherence.

Previous studies showed that complexity of AED regimens may have a crucial role in drug adherence of epilepsy patients. We hypothesized simplification of AED regimens would improve drug adherence and seizure control.

We retrospectively reviewed medical records of 1,958 patients treated with seizure or epilepsy in a tertiary referral hospital from March 2008 to December 2015. Among the 1,958 patients, 401 patients were classified as drug-resistant epilepsy, and poor compliance was considered as a cause of drug-resistant epilepsy in 113 patients. Eighty-eight of 113 patients were switched to once a day regimens.

Forty-six of 88 patients (52.3%) achieved seizure freedom or at least 70% improvement. Patients without MRI abnormality (p=0.035, 30/48 vs 16/40) and switching AED to extended-release formulation or to a different AED (p=0.012, 13/36 vs 33/52) were associated with better outcomes.

Our study suggests that switching AED to once a day regimen can improve seizure control in more than a half of epilepsy patients with poor drug adherence. Patients with several factors, including normal brain MRI and switching to AEDs with different formulation or mechanism may have a higher chance of successful switching.