Key result
Concomitant use of proton pump inhibitors did not significantly alter warfarin dose or INR, though the presence of atrial fibrillation was associated with a higher likelihood of an INR increase (OR 3.77).
Why the study?
Does the addition of proton pump inhibitors alter warfarin dose requirements or INR in patients on warfarin therapy?
Observational (n=108)
No
Does the addition of proton pump inhibitors alter warfarin dose requirements or INR in patients on warfarin therapy?
Odds Ratio: 3.77 (95% CI 1.16–12.27)
p-value: p=0.0227
Concomitant use of proton pump inhibitors and warfarin does not significantly alter the anti-coagulation effect of warfarin, suggesting no routine dose adjustment is necessary.
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.
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Shirayama et al. (2014) conducted an observational in Patients requiring anticoagulation with warfarin (n=108). Proton pump inhibitors (lansoprazole, omeprazole, rabeprazole) vs. Baseline (prior to PPI administration) was evaluated on Upper quartile of increment of INR (>0.690) associated with atrial fibrillation (OR 3.77, 95% CI 1.16 - 12.27, p=0.0227). Concomitant use of proton pump inhibitors did not significantly alter warfarin dose or INR, though the presence of atrial fibrillation was associated with a higher likelihood of an INR increase (OR 3.77).
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