title: Current use of domperidone and co-prescribing of medications that increase its arrhythmogenic potential among older adults: a population-based cohort study in Ontario, Canada.
abstract: OBJECTIVE
  Domperidone is commonly used to treat nausea and gastrointestinal disorders. Recent data suggests that it may increase the risk of sudden cardiac death, particularly in older people. Little is known about how it is used in contemporary practice. This study sought to characterize the population of older adults newly dispensed domperidone, describe dosages of domperidone used, and determine the frequency of co-prescribing domperidone with medications that may increase the arrhythmogenic potential of domperidone.
  
  
  METHODS
  This is a retrospective cohort study using administrative health database information from Ontario, Canada. Prescription medication records were obtained from the Ontario Drug Benefit Claims Database. Diagnostic codes were obtained from the Ontario Health Insurance Plan Database, the Canadian Institute for Health Information Discharge Abstract Database, and the same-day surgery database. Patients who received a new prescription for domperidone between April 1, 2003 and March 31, 2010 were included.
  
  
  RESULTS
  A total of 122,233 patients met inclusion criteria; 85 % were between 66 and 84 years old and 63 % were female. The mean estimated daily domperidone dose was 35 mg, and the estimated daily dose was <40 mg for 62 % of users. Strong or moderately strong cytochrome P-450 (CYP) 3A4 inhibitors were co-prescribed for 4.3 and 10.7 % of users, while medications with a known risk or possible risk for torsades de pointes (TdP) were co-prescribed to 18.3 and 18.8 % of users.
  
  
  CONCLUSIONS
  Older domperidone users were commonly co-prescribed drugs with the potential to increase the risk for TdP. These combinations should be avoided, as iatrogenic QT prolongation is a modifiable risk factor for TdP.
authors.affiliation: Schlegel Research Chair in Geriatric Pharmacotherapy, Schlegel-UW Research Institute for Ageing, University of Waterloo, 10 Victoria St S, Room 7004, Kitchener, ON, N2G 1C5, Canada, crojas-f@uwaterloo.ca.
authors.forename: Carlos
authors.initials: C
authors.lastname: Rojas-Fernandez
authors.forename: Anne L
authors.initials: AL
authors.lastname: Stephenson
authors.forename: Hadas D
authors.initials: HD
authors.lastname: Fischer
authors.forename: Xuesong
authors.initials: X
authors.lastname: Wang
authors.forename: Tiago
authors.initials: T
authors.lastname: Mestre
authors.forename: Janine R
authors.initials: JR
authors.lastname: Hutson
authors.forename: Margarita
authors.initials: M
authors.lastname: Pondal
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Lee
authors.forename: Paula A
authors.initials: PA
authors.lastname: Rochon
authors.forename: Connie
authors.initials: C
authors.lastname: Marras
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000932:Antiemetics / Q000008:administration & dosage / Q000009:adverse effects* / Q000493:pharmacokinetics; D015331:Cohort Studies; D065692:Cytochrome P-450 CYP3A Inhibitors / Q000008:administration & dosage / Q000009:adverse effects* / Q000493:pharmacokinetics; D004294:Domperidone / Q000008:administration & dosage / Q000009:adverse effects* / Q000493:pharmacokinetics; D004347:Drug Interactions; D005260:Female; D006801:Humans; D008297:Male; D009864:Ontario / Q000453:epidemiology; D010818:Practice Patterns, Physicians'; D012307:Risk Factors; D016171:Torsades de Pointes / Q000139:chemically induced* / Q000453:epidemiology / Q000378:metabolism
chemical_list: D000932:Antiemetics; D065692:Cytochrome P-450 CYP3A Inhibitors; D004294:Domperidone