Abstracts

Rationale: Authors of previous studies report that persons with epilepsy (PWE) have a lower rate of acceptance of the switch from brand antiepileptic medications (AEDs) to their generic equivalents. Recently, five AEDs have become available generically. We measured the difference in the overall rate of Brand Name Medically Necessary (BNMN) prescriptions compared to the rate of BNMN AEDs and the individual switchback rate (SBR) for specific AEDs in a community based medical care system. Methods: A retrospective data review for two time periods (1/1/08 -12/31/08 and 1/1/09 - 4/30/09) was performed from the electronic prescribing system of a rural community-based clinic practice. The primary endpoints include 1) comparison of the percentage of all prescriptions written BNMN versus AED prescriptions that were written BNMN 2) the percentage of patients who switchback to brand lamotrigine (LAM), levetiracetam (LVT), and divalproex (DVP) after being exposed to the generic. The secondary endpoint was a comparison of the percentage of prescriptions that were written BNMN for different therapeutic drug classes. Results: In 2008, over 1.8 million prescriptions were signed in the Marshfield Clinic electronic medical record (EMR). Of all prescriptions signed, < 0.5% were written BNMN. Approximately, 37,500 prescriptions were signed for AEDs regardless of diagnosis and ~2% of these prescriptions were written BNMN. A review of all BNMN prescriptions showed 12% (N=781) were AEDs. From January 1, 2009 to April 30, 2009, more than 600,000 prescriptions were signed in the Marshfield Clinic EMR. During this time period approximately the same percentage of total prescriptions were written BNMN (<0.5%) and the same percentage of total prescriptions were written for an AED(2%). However, the percentage of BNMN prescriptions that were AEDs was significantly greater (~20%, N=466) during this time period compared to 2008. A review of PWE who received LAM, DVP, or LVT revealed a SBR of 6%, 5%, and 4% respectively. Secondary analysis of BNMN prescriptions revealed Narrow Therapeutic Index medications (e.g. warfarin, levothyroxine, cyclosporine) combined encompassed ~27% of all BNMN prescriptions, while AEDs were the second most common therapeutic class with 20.6%. Conclusions: This retrospective review of prescribing data shows the vast majority of patients in this community do not require BNMN prescriptions for their healthcare. However, AEDs as a class or individually appear to have a higher rate of BNMN prescriptions compared to non-AEDs and the addition of new generic AEDs to the market has increased the percentage of BNMN prescriptions that are AEDs. The reasons for patients requiring the brand AEDs can and did vary, but in each case the prescribing provider felt that the brand AED was a better choice for the individual patient. While generic medications are generally well tolerated and often offer a cost savings, the higher SBR for AEDs suggests that switching to generic equivalents in this class should be reviewed and discussed on an individual basis.