Kidney Stone Risk for Patients Who Take Common Antiepileptic Medications

Topiramate and zonisamide, originally developed as antiseizure medications, are prescribed increasingly by generalists for other uses such as obesity management or migraine prophylaxis. Both topiramate and zonisamide might cause kidney stone formation by increasing urinary pH and decreasing urinary citrate, but real-world data establishing this association are lacking.

In this retrospective study, researchers used claims from U.S. Medicare and a commercial health plan to match 200,000 new users of topiramate or zonisamide with nonusers (based on age and sex). Patients with stone events (defined as a stone-related emergency room visit, hospitalization, or surgery) in the prior year were excluded.

In the commercial health plan cohort, 2.9% of t…