Abstracts

Rationale: To assess associations between particular antiepileptic drugs (AEDs) and whether patients with epilepsy are generic brittle (GB). Methods: Chi square and binary logistical regression analysis that focused on AED use was performed, using a previously described study in patients with epilepsy who were routinely followed at the University of Maryland epilepsy outpatient clinic in Baltimore, Maryland. Determination of generic brittleness - having worsened seizures, increased side effects, or a perception of a problem with AED formulation change, whether brand-to-generic or generic-to-generic - were based on patient reporting. Results: Across all n=148 patients, there were 30 unique AED products that totaled 530 formulations collectively taken.Taking lamotrigine immediate release (IR) tablets was associated with a greater probability of being GB. Six AEDs - Vimpat tablet, carbamazepine IR tablet, phenobarbital (any formulation), gabapentin capsule, Lyrica capsules, and phenytoin (any formulation) - were associated with a lower probability of being GB, as well as a lower probability of a patient having reported a problem switching AED formulations. It is not clear that the six AEDs associated with a lower probability of being GB actually protected against being GB through greater efficacy and tolerability or better formulation quality. An alternative explanation is that patients who have fewer seizures or less refractory epilepsy, and less inclined to be GB, are prescribed at least one of these six AEDs. Also, taking a higher number of AEDs significantly increased the odds of having reported a switch problem. Since tablet and capsule appearance can influence patient perceptions and outcomes, it was observed that the six AEDs associated with a lower probability of being GB tended to have fewer generics, and hence possibly lessened treatment uncertainties from the patient perspective. An additional observation was that, when a generic was available, GB patients took a generic AED 48.0% of the time, while non-GB patients took a generic AED 97.5% of the time. Conclusions: Taking lamotrigine IR tablets was associated with a greater probability of being GB. Six AEDs were associated with a lower probability of being GB. These associations were not clearly caused by greater or lesser AED efficacy and tolerability or formulation quality. Funding: Food and Drug Administration