Comparative effectiveness of add-on therapy with newer-generation antiepileptic drugs in Bulgarian patients with refractory epilepsy.

OBJECTIVES: The objective of this study is to perform an open, prospective study on various aspects of comparative effectiveness of newer-generation antiepileptic drugs as add-on therapy in Bulgarian patients with drug-resistant epilepsy.

METHODS: The study was performed with the participation of 1259 patients with epilepsy who attended the Clinic of Neurology at the University Hospital in Plovdiv, Bulgaria for regular visits and completed diaries about seizure frequency, severity, and adverse events.

RESULTS: Oxcarbazepine was used in 82 patients, topiramate in 120 patients, lamotrigine in 73 patients, levetiracetam in 135 patients, pregabalin in 47 patients, tiagabine in 43 patients, gabapentin in 18 patients, lacosamide in 12 patients, and retigabine in 6 patients. During the first 24 months of study, improvement of seizure severity and frequency was most frequent in patients on treatment with pregabalin and levetiracetam and rarest in those on treatment with oxcarbazepine. The retention rate of patients on pregabalin and tiagabine was significantly lower compared to the retention rate of patients on most of the other antiepileptic drugs. The frequency of adverse events was higher in patients on treatment with tiagabine and pregabalin.

CONCLUSION: Despite some similar characteristics of newer-generation antiepileptic drugs' effectiveness, levetiracetam stands out with better dynamic improvement of seizure severity and frequency and satisfactory tolerability; typical for pregabalin is a very good dynamic improvement of seizure severity and frequency mainly in patients with focal seizures, but a lower tolerability, and the main advantage of oxcarbazepine is a good tolerability, efficacy, however, is less satisfactory.