Aims: To investigate whether an interaction exists between amoxicillin/clavulanic acid (amoxiclav) and warfarin in patients treated with stable oral anticoagulant therapy.
Methods: In a double-blind, cross-over, placebo-controlled study, 12 patients on stable warfarin therapy, received a 7 day amoxiclav regimen or placebo.
Results: The mean maximum increase in INR observed was 0.22 ± 0.3 with amoxiclav vs. 0.24 ± 0.6 with placebo (P=0.94). The day 7-day 1 factor II, R(-) and S(-) warfarin plasma concentrations were similar during the amoxiclav and placebo study periods (P=0.81, P=0.45, P=0.75, respectively).
Conclusion: Amoxiclav did not modify anticoagulation in patients treated with stable warfarin therapy and without infection.
© 2011 The Authors. British Journal of Clinical Pharmacology © 2011 The British Pharmacological Society.