P.045 Use of sodium bicarbonate to alkalinize the urine in pediatric patients treated with Topiramate (pilot study)

Background: Topiramate is an antiepileptic frequently used in pediatrics with multiple mechanisms of action. This includes carbonic anhydrase inhibition, which has unclear relevance to its antiepileptic effect. Metabolic acidosis, hypocitraturia and nephrolithiasis are known side-effects of carbonic anhydrase inhibition and can limit therapeutic effect. Alkali therapy may normalize acidosis, increase urinary citrate, and reduce nephrolithiasis risk. We hypothesize that provision of sodium bicarbonate supplementation to patients with topiramate-induced acidosis will mitigate these side-effects without worsening seizure frequency or severity. Methods: Pediatric patients on antiepileptic therapy with topiramate are being recruited from outpatient pediatric neurology clinics at McMaster Children’s Hospital. We aim to recruit 20 patients with metabolic acidosis and 20 control patients. Measures include blood gas, electrolytes, urine electrolytes and citrate. Patients with metabolic acidosis will be given daily sodium bicarbonate for one month, followed by repeat bloodwork. Seizure frequency will be prospectively documented in all participants throughout the three-month period. Results: Recruitment is ongoing, and three patients (1 with acidosis) have been recruited thus far. Results will be analyzed with chi-squared and paired T tests. Conclusions: This pilot study is the first to evaluate the safety and efficacy of sodium bicarbonate supplementation in patients receiving topiramate for seizure control.