title: CYP2C19 drug-drug and drug-gene interactions in ED patients.
abstract: BACKGROUND
  CYP450 polymorphisms result in variable rates of drug metabolism. CYP drug-drug interactions can contribute to altered drug effectiveness and safety.
  
  
  OBJECTIVE
  The primary objective was to determine the percentage of emergency department (ED) patients with cytochrome 2C19 (CYP2C19) drug-drug interactions. The secondary objective was to determine the prevalence of CYP2C19 polymorphisms in a US ED population.
  
  
  METHODS
  We conducted a prospective observational study in an urban academic ED with 72,000 annual visits. Drug ingestion histories for the 48 hours preceding ED visit were obtained; each drug was coded as CYP2C19 substrate, inhibitor, inducer, or not CYP2C19 dependent. Ten percent of patients were randomized to undergo CYP2C19 genotyping using the Roche Amplichip.
  
  
  RESULTS
  A total of 502 patients were included; 61% were female, 65% were white, and median age was 39 years (interquartile range, 22-53). One hundred thirty-one (26.1%) patients had taken at least 1 CYP2C19-dependent home drug. Eighteen (13.7%) patients who were already taking a CYP2C19-dependent drug were given or prescribed a CYP2C19-dependent drug while in the ED. Among the 53 patients genotyped, 52 (98%) were extensive metabolizers and 1 was a poor metabolizer.
  
  
  CONCLUSIONS
  In a population of ED patients, more than a quarter had taken a CYP2C19-dependent drug in the preceding 48 hours, but few were given or prescribed another CYP2C19-dependent drug in the ED. On genotyping analysis, CYP2C19 polymorphisms were uncommon in our cohort. We conclude that changing prescribing practice due to CYP2C19 drug-drug interaction or genotype is unlikely to be useful in most US ED populations.
authors.affiliation: University of Colorado Department of Emergency Medicine, 12401 E 17th Ave, Aurora, CO, 80045.
authors.forename: Hanna K
authors.initials: HK
authors.lastname: Flaten
authors.affiliation: Denver Health Residency in Emergency Medicine, 770 Bannock St, Denver, CO, 80204.
authors.forename: Howard S
authors.initials: HS
authors.lastname: Kim
authors.affiliation: University of Colorado Department of Emergency Medicine, 12401 E 17th Ave, Aurora, CO, 80045.
authors.forename: Jenny
authors.initials: J
authors.lastname: Campbell
authors.affiliation: University of Colorado School of Medicine, 12401 E 17th Ave, Aurora, CO, 80045.
authors.forename: Lisa
authors.initials: L
authors.lastname: Hamilton
authors.affiliation: University of Colorado Department of Emergency Medicine, 12401 E 17th Ave, Aurora, CO, 80045; Denver Health Residency in Emergency Medicine, 770 Bannock St, Denver, CO, 80204; University of Colorado School of Medicine, 12401 E 17th Ave, Aurora, CO, 80045; Skaggs School of Pharmacy and Pharmaceutical Sciences, 12401 E 17th Ave, Aurora, CO, 80045; Rocky Mountain Poison & Drug Center, 990 Bannock St, Denver, CO, 80204. Electronic address: andrew.monte@ucdenver.edu.
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Monte
mesh_terms: D000328:Adult; D065731:Cytochrome P-450 CYP2C19 / Q000235:genetics*; D004347:Drug Interactions / Q000235:genetics*; D004636:Emergency Service, Hospital; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D010597:Pharmacogenetics / Q000379:methods*; D011110:Polymorphism, Genetic; D015995:Prevalence; D011446:Prospective Studies; D014481:United States / Q000453:epidemiology
chemical_list: D065731:Cytochrome P-450 CYP2C19