title: Prolonged effect of omeprazole on the 14C-urea breath test.
abstract: OBJECTIVE
  We investigated omeprazole's effect on 14C-urea breath testing. We also determined the duration of omeprazole's effect on the breath test. Finally, we studied whether effects on breath testing were dose dependent.
  
  
  METHODS
  Fifty-seven employees and outpatients were screened for Helicobactor infection. Those positive for serology, CLO, or histology were asked to undergo baseline breath testing. Those with a positive breath test took omeprazole 20 mg/day for 14 days followed by repeat breath testing, 1, 3, and 5 days after therapy. Subjects with persistently positive breath tests despite omeprazole 20 mg/day were asked to take omeprazole 20 mg b.i.d. for 14 days. Repeat breath tests were performed as above.
  
  
  RESULTS
  Thirteen of 57 had HP infection. Ten of 13 underwent a baseline breath test. Eight of 10 with baseline breath test experienced a significant decrease in expired 14CO2 after omeprazole 20 mg/day. Five of 13 with active HP infection developed a negative breath test after omeprazole. All subjects had a positive breath test within 5 days of stopping omeprazole 20 mg/day. Five of eight with persistently positive breath tests despite omeprazole 20 mg/day took omeprazole 40 mg/day. Four of five developed a significant decrease in 14CO2 excretion after omeprazole. All subjects had a positive breath test within 5 days of stopping omeprazole 40 mg/day.
  
  
  CONCLUSIONS
  Recent treatment with omeprazole 20 mg/day led to a false-negative breath tests in 38.5%. This effect appeared to be dose dependent and lasted up to 5 days after cessation of omeprazole.
authors.affiliation: Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109-0362, USA.
authors.forename: W D
authors.initials: WD
authors.lastname: Chey
authors.forename: M
authors.initials: M
authors.lastname: Spybrook
authors.forename: S
authors.initials: S
authors.lastname: Carpenter
authors.forename: T T
authors.initials: TT
authors.lastname: Nostrant
authors.forename: G H
authors.initials: GH
authors.lastname: Elta
authors.forename: J M
authors.initials: JM
authors.lastname: Scheiman
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001944:Breath Tests / Q000379:methods; D002250:Carbon Radioisotopes; D004305:Dose-Response Relationship, Drug; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D016481:Helicobacter Infections / Q000175:diagnosis / Q000188:drug therapy; D016480:Helicobacter pylori; D006801:Humans; D008297:Male; D008875:Middle Aged; D009853:Omeprazole / Q000008:administration & dosage / Q000494:pharmacology*; D012680:Sensitivity and Specificity; D013997:Time Factors; D014508:Urea / Q000032:analysis*
chemical_list: D000900:Anti-Bacterial Agents; D002250:Carbon Radioisotopes; D014508:Urea; D009853:Omeprazole