TITLE:
Interaction between Warfarin and Proton Pump Inhibitors
AUTHORS:
Takeshi Shirayama, Hirokazu Shiraishi, Akira Kuroyanagi, Tetsuro Hamaoka, Mikimasa Imai, Akimitsu Kojima
KEYWORDS:
Warfarin, Proton Pump Inhibitor, Interaction
JOURNAL NAME:
International Journal of Clinical Medicine,
Vol.5 No.14,
July
23,
2014
ABSTRACT: Background:
Interaction between proton pump inhibitors (PPI) and warfarin is controversial.
Previous clinical studies have only a short follow-up period. Methods and
Results: All patients (n = 716) for whom warfarin was prescribed from November
1, 2010 to October 30, 2011 were extracted from electronic health records. In
retrospective analysis for 1 year, PPI were prescribed to 404 patients. Among
them, 108 patients were taking warfarin for more than 6 weeks before and after
PPI. The profile of these patients was analyzed: 63 patients took lansoprazole;
15 patients took omeprazole; 30 patients took rabeprazole. No statistical
difference was observed among 3 groups in age, body weight, concomitant use of
other drugs, and comorbidity. Warfarin dose and INR did not change after PPI.
Multivariate stepwise logistic regression analysis revealed that upper quartile of increment of INR was associated with the
presence of atrial fibrillation (OR 3.77, 95% CI 1.16 - 12.27). The patients who had warfarin for shorter
periods before PPI, or those who had PPI first (n = 141) had similar dose of
warfarin and INR. In all patients analyzed (n = 404), including patients whose
follow-up periods were shorter than 6 weeks (n = 155), a patient had cerebral
bleeding, and 2 patients had cerebral infarction. Conclusions: Unfavorable
interaction between warfarin and PPI was negligible in clinical use. Relatively
higher INR was achieved after PPI in the presence of atrial fibrillation.