The efficacy and side effects of topiramate on refractory epilepsy in infants and young children: A multi-center clinical trial

OBJECTIVES This study has been conducted to assess the efficacy and safety of topiramate in refractory epilepsies in infants and young children. METHODS A prospective clinical trial was performed in three tertiary care hospitals, on 47 children aged 6-60 months with refractory epilepsy. Topiramate was added to at least two baseline anti-epileptic drugs. The efficacy was rated according to seizure type, frequency and duration. RESULTS Children with refractory epilepsy were classified according to their clinical, neuro-imaging, and neurophysiological profile into infantile spasms (IS) (9 cases, 19%), Lennox-Gastaut syndrome (LGS) (25 cases, 53%) and other epilepsies (13 cases, 28%). Children were also classified into cryptogenic and symptomatic epilepsy. Topiramate was introduced as add-on therapy in a daily dose of 1 mg/kg/day for 2 weeks, followed by increments of 1-3 mg/kg/day at 2-week intervals, up to a maximum of 10 mg/kg/day. After a minimum treatment period of 6 months, 28 (60%) of the children had a satisfactory response (completely seizure free, or more than a 50% seizure reduction). The remaining 19 children (40%) had an unsatisfactory response (50% or less reduction in seizure frequency, no change or increased seizure frequency). Topiramate appeared to be equally effective in infantile spasms, Lennox-Gastaut syndrome and children with other types of epilepsy, with no significant difference between those with a satisfactory and an unsatisfactory response (p=0.089). There was also no significant difference in response between patients with cryptogenic and symptomatic epilepsy (p=0.360). Mild to moderate adverse effects, mainly somnolence, anorexia and nervousness, were present in 25 (53%) of children. One of the children developed hypothyroidism. CONCLUSION Although the long term safety and possible adverse effects of topiramate have not been fully established in infants and young children, this study has shown that it is a useful option for children with frequent seizures unresponsive to standard anti-epileptic drugs.