Zonisamide - induced urinary lithiasis in patients with intractable epilepsy

We report here three patients with intractable epilepsy who developed urina ry lithiasis during zonisamide (ZNS) treatment. Abdominal pain due to left- sided hydronephrosis was the initial symptom in the first patient, and it w as resolved after the excretion of a stone. The second patient, who had no specific symptoms, was found to have a thick: sludge of calcium phosphate: in the bladder when he suffered from aspiration pneumonia and dehydration. The third patient, who had a history of recurrent urinary obstruction, was also found to have a thick sludge of calcium oxalate in the bladder. The ur inalysis of the three patients revealed alkaline urine and hypercalciuria. Although their urinary lithiasis was resolved by discontinuation of ZNS and supportive therapy, routine examination of urine parameters such as pn and sediments, and daily urine-output cheeks are thought to be necessary durin g treatment with ZNS, especially for patients who are bedridden tor a long time and receive multiple antiepileptic drugs. (C) 2000 Elsevier Science B. V. All rights reserved.