PROLONGED EFFECT OF OMEPRAZOLE ON THE C-14 UREA BREATH TEST

Objectives: We investigated omeprazole's effect on C-14-urea breath te sting. We also determined the duration of omeprazole's effect on the b reath test. Finally, we studied whether effects on breath testing were dose dependent. Methods: Fifty-seven employees and outpatients were s creened for Helicobacter 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 wit h persistently positive breath tests despite omeprazole 20 mg/day were asked to take omeprazole 20 mg b.i.d. for 14 days. Repeat breath test s were performed as above. Results: Thirteen of 57 had HP infection. T en of 13 underwent a baseline breath test. Eight of 10 with baseline b reath tests experienced a significant decrease in expired (CO2)-C-14 a fter omeprazole 20 mg/day. Five of 13 with active HP infection develop ed a negative breath test after omeprazole. All subjects had a positiv e 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 d ecrease in (CO2)-C-14 excretion after omeprazole. All subjects had a p ositive breath test within 5 days of stopping omeprazole 40 mg/day. Co nclusions: Recent treatment with omeprazole 20 mg/day led to false-neg ative breath tests in 38.5 %. This effect appeared to be dose dependen t and lasted up to 5 days after cessation of omeprazole.