title: Elevated sweat chloride concentration in children without cystic fibrosis who are receiving topiramate therapy.
abstract: BACKGROUND
  Topiramate, which is used as an anticonvulsant and for migraine prophylaxis in children, causes oligohydrosis as a side-effect, but its effect on sweat chloride concentrations has not been studied systematically.
  
  
  METHODS
  Twenty-one children receiving topiramate and 20 healthy controls with no signs or symptoms of pulmonary or gastrointestinal disease and a negative family history for cystic fibrosis (CF) underwent bilateral pilocarpine iontophoresis and sweat collection via Macroduct® system.
  
  
  RESULTS
  Adequate samples (>15 µl volume) were obtained from 17/19 topiramate subjects (89%), and 19/20 (95%) controls. The mean sweat chloride concentration was 37.7 ± 18.8 mmol/L for patients receiving topiramate, and 15.9 ± 6.9 mmol/L for controls (p = 0.0001). The mean sweat volume was 29.1 ± 17.4 µl for patients receiving topiramate, and 41.2 ± 17.5 µl for controls (p = 0.037). Overall 8/17 (47%) of patients on topiramate with a measurable sweat chloride had either an intermediate (>40 mmol/L but <60 mmol/L) or elevated (>60 mmol/L) sweat chloride test result, while 0/19 control subjects had elevated sweat chloride (p = 0.0008). Further analysis of the in vitro activity of topiramate on cultured human bronchial epithelial cells in modified Ussing chambers showed no differences in chloride conductance measured in cells exposed to 10 or 50 µg/ml of topiramate when compared to non-exposed cells.
  
  
  CONCLUSIONS
  This is the first report of a medication affecting sweat chloride values and shows that topiramate therapy can cause elevated sweat chloride concentrations in the absence of clinical manifestations of CF.
authors.affiliation: Division of Pediatric Pulmonology, Department of Pediatrics, Children's Hospital of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Lokesh
authors.initials: L
authors.lastname: Guglani
authors.forename: Bilal
authors.initials: B
authors.lastname: Sitwat
authors.forename: Darla
authors.initials: D
authors.lastname: Lower
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Kurland
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Weiner
mesh_terms: D000293:Adolescent; D000700:Analgesics / Q000627:therapeutic use; D000927:Anticonvulsants / Q000627:therapeutic use*; D001980:Bronchi / Q000187:drug effects; D002478:Cells, Cultured; D002648:Child; D002712:Chlorides / Q000032:analysis / Q000378:metabolism*; D003550:Cystic Fibrosis / Q000175:diagnosis; D005260:Female; D005632:Fructose / Q000031:analogs & derivatives* / Q000627:therapeutic use; D006801:Humans; D007478:Iontophoresis; D008297:Male; D008881:Migraine Disorders / Q000188:drug therapy; D010862:Pilocarpine / Q000008:administration & dosage; D013542:Sweat / Q000737:chemistry* / Q000187:drug effects; D000077236:Topiramate; D016896:Treatment Outcome
chemical_list: D000700:Analgesics; D000927:Anticonvulsants; D002712:Chlorides; D010862:Pilocarpine; D000077236:Topiramate; D005632:Fructose