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WCE 2017: Use of the Selective Cholesterol Absorption Inhibitor, Ezetimibe, and Subsequent Risk for Urolithiasis

Vancouver, Canada (UroToday.com) Dr. Andrew Ostrowski, clinical urology resident from the Mayo Clinic in Jacksonville, Florida, presented data that established the effect of the selective cholesterol absorption inhibitor, Ezetimibe, on the subsequent risk of urolithiasis. This was a response to Dr. Andrew Cohen’s abstract at AUA 2016 in which Dr. Cohen concluded that statins are protective against kidney stone formation. Dr. Ostrowski believed that not all statins would be protective against renal stone formation and so created a retrospective study of Mayo Clinic patients who took Ezetimibe, did not have hyperlipidemia, and had a history of nephrolithiasis, to determine the relationship between Ezetimibe and increased urinary oxalate levels. 

The premise of this study was based on how Ezetimibe acts on cholesterol and, subsequently, oxalate levels in the body. Ezetimibe works by blocking absorption of cholesterol through the intestinal wall. Increased concentration of cholesterol in the intestine allows fat and bile acids to react with calcium in the gut to decrease the amount of calcium that can bind to oxalate. This increases the free intestinal oxalate, increasing oxalate absorption and so also oxalate levels in the urine.

The research team therefore compared the oxalate levels in the urine of patients during Ezetimibe medication to the oxalate levels of the urine pre- or post- Ezetimibe medication. Though he only had 11 patients and so could not establish significance, he found that the average urinary oxalate of patients on Ezetimibe was 0.32 mmol/spec and the average urinary oxalate of patients while off of Ezetimibe was 0.27 mmol/spec, significant with a higher number of patients.

Dr. Ostrowski concluded that, given that elevated urinary excretion of oxalate predisposes patients to formation of calcium oxalate stones, it stands to reason that a similar correlation could potentially exist between Ezetimibe and calcium oxalate urinary stone formation. He next plans to increase his patient population to further explore the correlation between this drug and calcium oxalate stone formation. While completing this next leg of research, he cautions physicians to keep this relationship between Ezetimibe and stones in mind as they treat patients with recurrent calcium oxalate stones taking Ezetimibe.

Presented by: Dr. Andrew Ostrowski 

Authors: Andrew Ostrowski, Raymond Pak, Ivan Porter
Affiliation: Mayo Clinic Jacksonville, Florida

Written by: Vinay Cooper Department of Urology, University of California - Irvine, at 35th World Congress of Endourology– September 12-16, 2017, Vancouver, Canada.