title: Topiramate increases biochemical risk of nephrolithiasis.
abstract: The incidence of renal stone disease in patients receiving topiramate (Topamax) is 2-4 times that expected in the background population. This has been attributed to a weak carbonic anhydrase inhibitor effect, but published data are scant. Following three cases of renal stones in patients receiving topiramate, we evaluated biochemical risk for nephrolithiasis in eight further unselected patients. Most patients demonstrated inadequate urinary acidification and hypocitraturia; in some cases citrate was undetectable. Several patients also had other risk factors for nephrolithiasis, including increased urinary sodium, calcium and oxalate excretion. The biochemical changes induced by topiramate appear highly penetrant. Experience with this drug is relatively short-lived and it is being prescribed for long-term use in (often) relatively young patients. This report highlights the significantly increased metabolic risk of stone formation in patients receiving topiramate.
authors.affiliation: Department of Clinical Biochemistry, East Kent Hospitals NHS Trust, Kent and Canterbury Hospital, Canterbury, CT1 3NG, UK. edmund.lamb@ekht.nhs.uk
authors.forename: Edmund J
authors.initials: EJ
authors.lastname: Lamb
authors.forename: Paul E
authors.initials: PE
authors.lastname: Stevens
authors.forename: Lina
authors.initials: L
authors.lastname: Nashef
mesh_terms: D000328:Adult; D002118:Calcium / Q000652:urine; D019343:Citric Acid / Q000652:urine; D004828:Epilepsies, Partial / Q000188:drug therapy; D005260:Female; D005632:Fructose / Q000009:adverse effects* / Q000031:analogs & derivatives* / Q000627:therapeutic use; D006801:Humans; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D007669:Kidney Calculi / Q000139:chemically induced* / Q000652:urine; D008297:Male; D008875:Middle Aged; D018696:Neuroprotective Agents / Q000009:adverse effects* / Q000627:therapeutic use; D010070:Oxalates / Q000652:urine; D012307:Risk Factors; D012964:Sodium / Q000652:urine; D000077236:Topiramate
chemical_list: D018696:Neuroprotective Agents; D010070:Oxalates; D000077236:Topiramate; D019343:Citric Acid; D005632:Fructose; D012964:Sodium; D002118:Calcium