Double-blind, placebo-controlled, cross-over trial of allopurinol as add-on therapy in childhood refractory epilepsy.

We report the results of a double-blind, placebo-controlled cross-over trial with allopurinol as add-on therapy in childhood refractory epilepsy. Seventeen patients received allopurinol and matched placebo for 12 weeks in 2 doses (10 mg/kg/day during the first week and 15 mg/kg/day thereafter with a washout period of 2 weeks between treatment phases. The total number of seizures was reduced by 50-98% in 4 patients (23.5%) and by 25-49% in another 4 (23.5%). However, the number of seizures remained unchanged in 5 patients (29.4%) and worsened in 4 (23.5%). Adverse side effects (17.6%) were generally mild and transient, suggesting that allopurinol is well-tolerated. A mean follow-up of 10 months of the responders did not show any relevant efficacy of allopurinol as an adjuvant therapy for refractory epilepsy, even at high doses.