Low-dose topiramate in adults with treatment-resistant partial-onset seizures.
OBJECTIVE
Based on dose predictions from animal and human volunteer studies, most patients enrolled in initial randomized controlled trials of topiramate as adjunctive therapy in adults with partial-onset seizures were randomized to >or= 600 mg/day topiramate. Subsequent experience suggests that dosage needs were overestimated. This double-blind, placebo-controlled study evaluated 200 mg/day topiramate in adults with treatment-resistant partial-onset seizures receiving a concurrent enzyme-inducing antiepileptic agent (carbamazepine).


METHODS
After a 4-week baseline, 263 adults receiving carbamazepine who had at least three partial-onset seizures during the baseline period were randomized to placebo or one of two topiramate 200 mg/day treatment arms: topiramate escalated weekly 25 mg/day(8-week escalation) or 50 mg/day(4-week escalation). Therapy was then maintained for the remainder of the 12-week double-blind study.


RESULTS
Median percent reduction in seizure frequency from baseline to study end was 44% with topiramate and 20% with placebo (P <or= 0.001). A significant therapeutic effect was present at 2 weeks with a dose of 100 mg/day. The most common adverse events (>or=10% incidence in topiramate-treated patients) were somnolence, fatigue, paresthesia, nervousness and anorexia; 8% of topiramate-treated patients and 2% of placebo-treated patients discontinued because of adverse events. As a result of the low incidence of adverse events, differences between titration rates in terms of tolerability were not detected.


CONCLUSIONS
Topiramate 200 mg/day is an appropriate target dose as adjunctive therapy in adults with treatment-resistant partial-onset seizures, even when receiving an enzyme-inducing agent; 100 mg/day also appears to be effective. A significant therapeutic effect may be seen in the second week of treatment with a dose of 100 mg/day.
Guberman
A
A
The Ottawa Hospital, Ottawa, ON, Canada. aguberman@ottawahospital.on.ca
Neto
W
W
Gassmann-Mayer
C
C
D000293:Adolescent; D000328:Adult; D000368:Aged; D000927:Anticonvulsants / Q000008:administration & dosage / Q000627:therapeutic use*; D002220:Carbamazepine / Q000627:therapeutic use; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D004828:Epilepsies, Partial / Q000188:drug therapy*; D005260:Female; D005632:Fructose / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D000077236:Topiramate; D016896:Treatment Outcome
D000927:Anticonvulsants; D000077236:Topiramate; D005632:Fructose; D002220:Carbamazepine