Abstracts

ZNS is a broad-spectrum anticonvulsant with multiple mechanisms of action. Little information is available regarding how patients of different age groups respond to treatment with ZNS. This study was conducted to evaluate the safety and efficacy of zonisamide (ZNS) in patients of different age groups.
This retrospective chart review included ZNS-treated patients with a variety of seizure types who were categorized according to their age: 0 to 19.9 years (group 1), 20 to 39.9 years (group 2), 40 to 59.9 years (group 3), and [gt]60 years (group 4). Patients in each age group were evaluated for ZNS dosage, concomitant medication use, reduction in seizure frequency, and adverse events.
A total of 100 patients were evaluated: 7 in group 1, 47 in group 2, 35 in group 3, and 11 in group 4. Mean ZNS dosages were similar among the age groups: 450 mg/d in group 1 (n=6), 391 mg/d in group 2 (n=45), 416 mg/d in group 3 (n=31), and 475 mg/d in group 4 (n=10). ZNS discontinuation rates ranged from 27% in group 4 to 43% in group 3. Most common reasons for discontinuation were side effects (14% group 1, 17% group 2, 26% group 3, and 27% group 4) and inefficacy (14% group 1, 17% group 2, 17% group 3, 0% group 4). The proportion of patients receiving concomitant medications ranged from 45% in group 2 to 64% in group 4. The number of concomitant medications used ranged from 1 to 3. The proportion of patients having a 100% reduction in seizure frequency was 14% for group 1, 19% for group 2, 20% for group 3, and 27% for group 4. A 75% to 99.9% seizure frequency reduction was seen in 14% of patients in group 1, 19% in group 2, 17% of group 3, and 27% of group 4. Seizure frequency reduction was 50% to 74.9% for no patients in group 1, 15% in group 2, 14% in group 3, and 9% of group 4. A 25% to 49.9% seizure frequency reduction was seen in no patients in group 1, 4% in group 2, 14% in group 3, and no patients in group 4. A [lt]25% seizure reduction was seen in 43% of patients in group 1, 43% in group 2, 34% in group 3, and 36% in group 4. Group 1 also had 29% of patients for whom seizure frequency reduction data were unavailable. The proportion of patients experiencing side effects was 57% in group 1, 30% in group 2, 34% in group 3, and 36% in group 4. Behavioral side effects were most commonly reported (14% group 1, 2% group 2, 3% group 3, 0% group 4).
The results of this study indicate that ZNS was just as effective (or more effective) and just as well tolerated (or better tolerated) in the oldest patient group ([gt]60 years) when compared with each of the younger patient groups. These data also suggest that ZNS is effective as monotherapy and in treating both partial and primary generalized seizures. Further research is warranted to confirm the findings of this study.