Abstracts

Rationale: Lamotrigine is a newer generation antiepileptic that has been used frequently over the last several years due to its broad treatment spectrum and favorable side effect profile. This study evaluated the success rates of switching to Lamotrigine from other antiepileptic medications, and examined patient subtypes that appeared to be more responsive to this medication. Methods: Medical records of 490 patients aged between 18 and 75 who attended the epilepsy clinic at the University of Nebraska Medical Center from January 2007 to January 2009 were reviewed. In 48 patient cases, Lamtorigine was utilized in place of a prior antiepileptic drug. Patients were subsequently followed for breakthrough seizures or side effects. Patients in whom the Lamotrigine switch yielded a decrease in seizure frequency to less than 50 % were considered successful. Cases in which the Lamotrigine switch was not successful were classified as therapeutic failure, and the causes for this were identified. Results: 19 males and 29 females were identified and followed (mean age = 32). Previous antiepileptic medications that were switched included leviteracetam (13), phenytoin (13), topiramate (3), carbamazepine (6), valproate(10), oxcarbazepine(1), felbamate (1), methsuximide (1). 33 of the cases (69%) were switched to lamotrigine successfully and 15 cases were not successful. In successful cases, mean seizure frequency decreased from 4.35 per month to 0.7 per month and 19 of these patients (54%) were on monotherapy for epilepsy at the time of the switch. Reasons for an unsuccessful switch included: inability to afford the medication (2), therapeutic failure (7), rash (2), other side effects (3) and non compliance (1). In cases where Lamotrigine switch was unsuccessful due to therapeutic failure, 86% (6/7) had abnormal MRI with focal findings and were on polytherapy. Conclusions: Switching to lamotrigine from other antiepileptic medications appears to be successful, particularly in patients on prior monotherapy. This finding is notable due to the ease of initiating this medication in the outpatient setting, and its overall paucity of side effects. Factors that may complicate success with switching include polytherapy and abnormal imaging findings.