title: Urolithiasis in patients on high dose felbamate.
abstract: OBJECTIVE
  We report 4 cases of felbamate urolithiasis. We identified only 1 prior case report of a felbamate stone. Felbamate is an antiepileptic drug used to treat refractory seizures and has minor side effects when given in recommended doses. We analyzed the characteristics, evaluation, treatment and outcomes in this challenging group of patients.
  
  
  METHODS
  Following institutional review board approval, we conducted a retrospective chart review of all patients who presented with a diagnosis of urolithiasis, were on felbamate and had stone analysis consistent with a felbamate origin.
  
  
  RESULTS
  All 4 patients had refractory seizures and 3 had severe developmental delay. Presentation ranged from an incidental finding to gross hematuria to agitation and pain. Stones were not visible on plain x-ray except in 1 case involving mixed stone composition. Decrease or cessation of the drug has not been feasible in 2 patients, and 3 patients have had recurrent stones. Initial stone analysis did not correctly identify the stone composition as felbamate in 2 cases, suggesting that the origin of these stones may not always be recognized.
  
  
  CONCLUSIONS
  We report the occurrence of felbamate stones in a series of patients on high dose felbamate therapy. Accurate diagnosis is made more difficult by the clinical complexity of the patient population (including severe developmental delay), the radiolucent nature of the stones and the possibility of inaccurate analysis of stone composition.
authors.affiliation: Department of Urology, Children's Hospital of Wisconsin, Milwaukee, Wisconsin 53226, USA.
authors.forename: Anas I
authors.initials: AI
authors.lastname: Ghousheh
authors.forename: Travis W
authors.initials: TW
authors.lastname: Groth
authors.forename: Kathy M
authors.initials: KM
authors.lastname: Fryjoff
authors.forename: David F
authors.initials: DF
authors.lastname: Wille
authors.forename: Neil S
authors.initials: NS
authors.lastname: Mandel
authors.forename: John T
authors.initials: JT
authors.lastname: Roddy
authors.forename: Charles T
authors.initials: CT
authors.lastname: Durkee
mesh_terms: D000293:Adolescent; D000927:Anticonvulsants / Q000009:adverse effects*; D002648:Child; D000078328:Felbamate; D005260:Female; D006801:Humans; D008297:Male; D048448:Phenylcarbamates / Q000009:adverse effects*; D011409:Propylene Glycols / Q000009:adverse effects*; D012189:Retrospective Studies; D052878:Urolithiasis / Q000139:chemically induced*; D055815:Young Adult
chemical_list: D000927:Anticonvulsants; D048448:Phenylcarbamates; D011409:Propylene Glycols; D000078328:Felbamate