Adjunctive Treatment for Partial Onset Epilepsy in Infants and Toddlers (1 to 24 months) 

Safety and effectiveness in patients below the age of 2 years have not been established for the adjunctive therapy treatment of partial onset seizures, primary generalized tonic-clonic seizures, or seizures associated with Lennox-Gastaut syndrome. In a single randomized, double-blind placebo-controlled investigational trial, the efficacy, safety, and tolerability of topiramate oral liquid and sprinkle formulations as an adjunct to concurrent antiepileptic drug therapy in infants 1 to 24 months of age with refractory partial onset seizures, was assessed. After 20 days of double-blind treatment, topiramate (at fixed doses of 5, 15, and 25 mg/kg per day) did not demonstrate efficacy compared with placebo in controlling seizures.

In general, the adverse reaction profile in this population was similar to that of older pediatric patients, although results from the above controlled study, and an open-label long-term extension study in these infants/toddlers (1 to 24 months old) suggested some adverse reactions/toxicities (not previously observed in older pediatric patients and adults; i.e, growth/length retardation, certain clinical laboratory abnormalities, and other adverse reactions/toxicities that occurred with a greater frequency and/or greater severity than had been recognized previously from studies in older pediatric patients or adults for various indications. 

These very young pediatric patients appeared to experience an increased risk for infections (any topiramate dose 12%, placebo 0%) and of respiratory disorders (any topiramate dose 40%, placebo 16%). The following adverse reactions were observed in at least 3% of patients on topiramate and were 3% to 7% more frequent then in patients on placebo: viral infection, bronchitis, pharyngitis, rhinitis, otitis media, upper respiratory infection, cough, and bronchospasm. A generally similar profile was observed in older children [see Adverse Reactions (6)]. 

Topiramate resulted in an increased incidence of patients with increased creatinine (any topiramate dose 5%, placebo 0%), BUN (any topiramate dose 3%, placebo 0%), and protein (any topiramate dose 34%, placebo 6%), and an increased incidence of decreased potassium (any topiramate dose 7%, placebo 0%). This increased frequency of abnormal values was not dose-related. Creatinine was the only analyte showing a noteworthy increased incidence (topiramate 25 mg/kg/d 5%, placebo 0%) of a markedly abnormal increase [see Warnings and Precautions (5.13)]. The significance of these finding is uncertain. 

Topiramate treatment also produced a dose-related increase in the percentage of patients who had a shift from normal at baseline to high/increased (above the normal reference range) in total eosinophil count at the end of treatment. The incidence of these abnormal shifts was 6 % for placebo, 10% for 5 mg/kg/d, 9% for 15 mg/kg/d, 14% for 25 mg/kg/d, and 11% for any topiramate dose [see Warnings and Precautions (5.13)]. There was a mean dose-related increase in alkaline phosphatase. The significance of these finding is uncertain. 

Topiramate produced a dose-related increased incidence of treatment-emergent hyperammonemia. [see Warnings and Precautions (5.8)]. 

Treatment with topiramate for up to 1 year was associated with reductions in Z SCORES for length, weight, and head circumference. [see Warnings and Precautions (5.4) and Adverse Reactions (6)]. 

In open-label, uncontrolled experience, increasing impairment of adaptive behavior was documented in behavioral testing over time in this population. There was a suggestion that this effect was dose-related. However, because of the absence of an appropriate control group, it is not known if this decrement in function was treatment related or reflects the patient’s underlying disease (e.g., patients who received higher doses may have more severe underlying disease) [see Warnings and Precautions (5.5)]. 

In this open-label, uncontrolled study, the mortality was 37 deaths/1000 patient years. It is not possible to know whether this mortality rate is related to topiramate treatment, because the background mortality rate for a similar, significantly refractory, young pediatric population (1-24 months) with partial epilepsy is not known. 

Monotherapy Treatment in Partial Onset Epilepsy in Patients <10 Years Old 

Safety and effectiveness in patients below the age of 10 years have not been established for the monotherapy treatment of epilepsy. 

Juvenile Animal Studies 

When topiramate (30, 90 or 300 mg/kg/day) was administered orally to rats during the juvenile period of development (postnatal days 12 to 50), bone growth plate thickness was reduced in males at the highest dose, which is approximately 5-8 times the maximum recommended pediatric dose (9 mg/kg/day) on a body surface area (mg/m2) basis.