Abstracts

Rationale: Epilepsy is associated with high odds of depression and older age is a unique risk factor for depression. In the context of the Treatment in Geriatric Epilepsy Research (TIGER) project, this study identified potential drug interactions in older veterans with mental illness started on an AED for new onset epilepsy. Methods: Using National Veterans Affairs and Medicare databases, we identified veterans aged 66 and older with a new diagnosis of epilepsy (1999-2004) and a pre-existing mental health diagnosis. Potential interactions were identified based on a literature review and were identified based on initial AED prescription and existing prescribed psychotropic agents.Results: Of 9,682 older adults with new onset epilepsy, 1,565 (16.2%) had an existing mental health diagnosis. The majority were white (80.8%) and male (97.4%) reflecting the VA patient population. The most commonly identified mental health condition, in isolation or combination, was depression (1,142/73%) followed by anxiety (660/38.3%) and PTSD (210/13.4%). Potential drug interactions between a newly prescribed AED and a medication prescribed for an existing mental health condition were identified in the majority (1,058/67.6%). The majority of the potentially interacting AEDs were enzyme inducing drugs, most commonly phenytoin. The most common psychotropic medications with potential pharmacokinetic interactions were: sertraline, trazadone, paroxetine and risperidone. 134/1,565 (8.6%) required hospitalization during the study and there was no significant difference between hospitalization rates between those with and those without potential drug interactions.Conclusions: The majority of VA patients over the age of 66 with a mental health diagnosis treated for new onset epilepsy had a potential drug interaction with the newly prescribed AED and an existing psychotropic prescription. The majority of these patients had depression and were on antidepressants suggesting that clinicians must be vigilant in monitoring patients for signs of worsening mental health following initiation of treatment for new onset epilepsy.