The purpose of this study is to evaluate the tolerability, safety and efficacy of topiramate in infants with refractory partial onset seizures (POS).

This is a world wide, multicenter, randomized, double-blind, placebo-controlled study to evaluate the tolerability, safety and efficacy of 3 target doses (5, 15, and 25 mg/kg/day) of topiramate compared with placebo as an adjunct therapy in infants with refractory partial onset seizures (POS). There are 4 phases to the study, a screening phase of 3 days, a double blind treatment phase of 20 days, a one year open label extension phase and a posttreatment (taper and withdrawal) phase. The oral liquid formulation will also be assessed during this study, as it is investigational, unlike the marketed sprinkle formulation. 5, 15, 25 mg/kg/day of topriramate sprinkle and oral liquid formulation will be administered during the four phases of the study.

Inclusion Criteria:

• 1-24 months, inclusive
• Concurrent 1 or 2 antiepileptic drugs
• Receiving regular enteral feedings
• Weigh between 3.5 and 15 kg
• Clinical or EEG evidence of simple or complex POS

Exclusion Criteria:

• Exclusively breast fed and cannot take medicine by mouth
• Surgically implanted and functioning vagus nerve stimulator
• Renal stones
• Medically uncontrolled illnesses or conditions
• Infantile seizures as a result of a correctable medical condition
• Progressive neurologic disorder