Abstracts

Rash is a well known side effect of antiepileptic drug (AED) therapy. Some patients develop rash from multiple AEDs. Very few studies have attempted to determine the frequency of cross-sensitivity of rashes among all AEDs.
Our objective was to determine the rates of cross-sensitivity of rash occurring with use of older and newer AEDs in patients with epilepsy., As part of the Columbia AED Database, we reviewed the incidence of AED-related rash for 1875 patients with epilepsy [ge]12 years old, including a history of AED rash at any age. We compared the rate of rash when these patients were taking any of the 15 most commonly used AEDs at our center: carbamazepine (CBZ), clobazam (CLB), felbamate (FBM), gabapentin (GBP), levetiracetam (LEV), lamotrigine (LTG), oxcarbazepine (OXC), phenobarbital (PB), phenytoin (PHT), primidone (PRM), tiagabine (TGB), topiramate (TPM), vigabatrin (VGB), valproic acid (VPA) & zonisamide (ZNS). We compared the rates of rash for each AED in patients who had or did not have a rash to: 1) another specific AED; 2) any other AED; & 3) any 2 other AEDs. Data were analyzed with chi-square or Fisher exact tests, with significance set at p[lt]0.05., 14.3% (269/1875) of patients had a rash attributed to at least one AED; 2.8% (72/1875) of patients had a rash from [ge]2 AEDs. Rates of rash & cross-sensitivity for the 6 AEDs most commonly causing rash are shown in Table 1. Results of all 15 AEDs will be presented.[table1], The cross-sensitivity rates for rashes involving CBZ & PHT range from 42-58%, those involving CBZ & LTG range from 20-26%, and those involving LTG & PHT range from 19-39%. For most AEDs, the risk of developing a rash increases at least two- to threefold if the patient has a rash to one or more other AEDs., (Supported by Elan, GlaxoSmithKline, Novartis, Ortho-McNeil, Pfizer & UCB Pharma.)