Abstracts

Over 2 million serious adverse drug reactions occur annually leading to 100,000 deaths in the United States. The objective of this study was to present the results of the investigation conducted in epileptic patients initiating either an enzyme-inducing AED (EIAED) or a non enzyme-inducing AED (NEIAED) and their risk of exposure to medications that may incur a potentially adverse PK interaction within a chronologically diverse group of epileptic patients. Specifically, this analysis sought to determine in a group of patients receiving only AED treatment, the risk that a concomitant, potentially interacting drug will be added to a patient medication regimen., A retrospective cohort study was conducted in epilepsy patients using a US claims Database (1/2001-12/2004). Patients were sub-grouped: EIAEDs (N=9296) or NEIAEDs (N=6573). A non-AED concomitant medication is defined as a concomitant medication if there exists an overlap with AED treatment of at least 5 days for antibiotics and antifungals and at least 30 days for other classes of drugs. Risk of first addition of a comedication was assessed using a Cox proportional hazard model adjusted to clinical and demographic characteristics including gender, state of the patient during the 6 months prior to AED initiation (based on Charlson comorbidity index, a measure of seriousness of comorbid diseases, Charlson et al., 1987), the type of AED treatment and the age group. Origin time is the date of the first prescription of AED., 2873 patients are censored (18%).The mean time under AED is 395 days (SD=371). The mean time to addition of first concomitant medication or to end of the follow-up for censored patient is 67 days (SD=156). The hazard ratios for the time to first concomitant medication addition are presented in Table 1.[table1], The risk that a concomitant medication will be added at some time after AED is initiated is significantly higher for females, increases with age and the severity of the state of the patient. This implies that patients with certain characteristics should have their antiepileptic drugs selected to avoid the potential of future drug interactions. This might include avoiding enzyme inducing antiepileptic drugs., (Supported by UCB INC.)