Topiramate increases biochemical risk of nephrolithiasis

Area of Science:

• Nephrology
• Pharmacology
• Urology

Background:

• Topiramate (Topamax) is associated with a 2-4 fold increased incidence of renal stone disease.
• This effect is hypothesized to be due to its weak carbonic anhydrase inhibitor properties, though data are limited.

Observation:

• Three cases of renal stones in patients on topiramate prompted further investigation.
• Biochemical risk factors for nephrolithiasis were evaluated in eight additional unselected patients receiving topiramate.

Findings:

• Most patients exhibited inadequate urinary acidification and hypocitraturia, with undetectable citrate in some cases.
• Several patients also presented with other risk factors, including elevated urinary sodium, calcium, and oxalate.
• The biochemical alterations induced by topiramate appear to be highly prevalent in patients.

Implications:

• Topiramate significantly increases the metabolic risk for kidney stone formation.
• Given its long-term use in younger populations, these findings highlight a critical safety concern.
• Further research and clinical monitoring are warranted for patients on long-term topiramate therapy.