Abstracts

Felbamate (FBM) use has dramatically declined since 1994 following reports of FBM induced aplastic anemia and liver failure. FBM prescribing in epilepsy centers has continued due to efficacy in intractable epilepsy patients. Limited published data is available on the clinical experience of FBM use since 1994. This study reflects our experience with FBM use in adults with intractable epilepsy.
Fifty patients (age 16 years and older) treated at the Minnesota Epilepsy Group, PA were prescribed FBM after August 1994. These patients were identified by an evaluation on the epilepsy unit from January 2001 through December 2002. Their records were reviewed. Data was tabulated and analyzed to include patient demographics, efficacy and tolerability. Paired [italic]t[/italic] tests were calculated to compare mean seizure frequency prior to FBM use and at FBM optimization.
Of the initial 50 patients reviewed, 20 were female and 30 were male. Mean age at time of starting FBM was 35.2 years (range 16 -73 years). The median number of past AEDs failed was 8 (3-16). Baseline monthly seizure frequency averaged 35/month (mean=19/month). Baseline frequency per seizure type: 5 GTCs/month, 21 CPS/month, 16 SPS/month, 36 tonic seizures/month, and 34 myoclonic seizures/month. Duration of FBM therapy ranged from 3 to 120 months (mean: 28.5, median: 13) with an average FBM maximum dose 3500-mg/day. Responder rate ([ge]50% reduction in baseline seizure frequency) was 66% with 40% (20/50) having [gt]75% reduction in baseline monthly seizures. The average reduction in baseline frequency per seizure type: GTCs (n=24), 70.7% (p=0.001); CPS (n=38), 54.9% (p=0.001); tonic seizures (n=12), 58.5% (p=0.005); myoclonic seizures (n=8), 56.5% (p=0.023). The average reduction in SPS (n=5) was 47.3% (ns). Eight patients (16%) became seizure free. 12/50 patients have retried FBM after discontinuing it due to the announcement of the risk of FBM induced aplastic anemia and liver failure in 1994. Eleven of these patients remain on FBM with 8 patients (72.7%) having a [ge]50% reduction in seizures. FBM was discontinued in 16% of patients (8/50) due to a lack of efficacy (50%), intolerable side effects (12.5%) or both (37.5%). Side effects documented as a reason for discontinuation include significant aggression, weight loss, and insomnia. No abnormal hepatic or hematological complications were documented. 42/50 patients (84%) remain on FBM an average of 27.4 months.
In adults with intractable seizures including GTCs, CPS, tonic and myoclonic seizures, FBM initially appears significantly effective in reducing mean baseline seizure frequency [gt]50% with some patients becoming seizure free. It appears to be tolerated with few discontinuations related to side effects. FBM remains an important treatment consideration in patients with intractable epilepsy.