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Case Reports in Medicine
Volume 2013 (2013), Article ID 629381, 3 pages
http://dx.doi.org/10.1155/2013/629381
Case Report

Silicate Urolithiasis during Long-Term Treatment with Zonisamide

1Department of Urology, Tokyo Teishin Hospital, Tokyo 102-8798, Japan
2Department of Urology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
3Department of Laboratory Medicine, Tokyo Teishin Hospital, Tokyo 102-8798, Japan
4Department of Hospital Pharmacy, Tokyo Teishin Hospital, Tokyo 102-8798, Japan

Received 26 April 2013; Revised 25 May 2013; Accepted 23 June 2013

Academic Editor: Ron Rabinowitz

Copyright © 2013 Satoru Taguchi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Silicate urinary calculi are rare in humans, with an incidence of 0.2% of all urinary calculi. Most cases were related to excess ingestion of silicate, typically by taking magnesium trisilicate as an antacid for peptic ulcers over a long period of time; however, there also existed unrelated cases, whose mechanism of development remains unclear. On the other hand, zonisamide, a newer antiepileptic drug, is one of the important causing agents of iatrogenic urinary stones in patients with epilepsy. The supposed mechanism is that zonisamide induces urine alkalinization and then promotes crystallization of urine components such as calcium phosphate by inhibition of carbonate dehydratase in renal tubular epithelial cells. Here, we report a case of silicate urolithiasis during long-term treatment with zonisamide without magnesium trisilicate intake and discuss the etiology of the disease by examining the silicate concentration in his urine.