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Background: Salsalate may offer many advantages over other non-steroidal antiinflammatory agents in patients taking warfarin, however a drug-drug interaction may occur which has not been reported in the medical literature or by the manufacturer of salsalate., Objective: To report a case of warfarin potentiation associated with salsalate treatment, which resulted in bleeding., Method: Clinical review of the course of a patient, who was stable on warfarin when salsalate therapy was added for chronic pain., Case Report: A patient taking stable doses of warfarin for over 1 year (with good control) was prescribed salsalate 3 g/day for pain in his knee and lower back. Approximately 1 month later he presents to the anticoagulation clinic with bruising and an International Normalized Ratio (INR) of 6.8. The patient had a good response to his salsalate therapy and wanted to continue it. The warfarin was held for 3 days and dose lowered by 50 %. His bruising then subsided and he had good control of his warfarin therapy with INRs ranging from 1.9 to 2.2 over the next 4 months. The patient was then lost to follow up., Conclusion: This case illustrates a strong association between starting salsalate and subsequent potentiation of warfarin, which heretofore has not been reported in the medical literature., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Purple toe syndrome is a rarely reported adverse effect of warfarin. In all described cases, the syndrome occurred relatively quickly after initiation of warfarin with little recommendation for treatment in patients needing continued anticoagulation. We encountered a patient who developed purple toes after 1 year of warfarin therapy. The warfarin was stopped, and fondaparinux was substituted with prompt resolution of all his symptoms. This is the first case describing late onset purple toe syndrome with warfarin with successful substitution with fondaparinux.

What Is Already Known About This Subject: Case reports suggest an association between cranberry juice and potentiation of warfarin. Studies using 240 ml of cranberry juice daily demonstrated no interaction. It is unknown if higher amounts of cranberry juice will interact with warfarin., What This Study Adds: Cranberry juice at 240 ml twice daily does not alter the pharmacodynamics of warfarin., Aim: To determine if high-dose cranberry juice (240 ml twice daily) alters the pharmacodynamic action of warfarin., Methods: Ten male patients taking stable doses of warfarin were given cranberry juice at 240 ml twice daily for 7 days. Prothrombin times were drawn at baseline and days 2, 6 and 8 after administration of the juice. Prothrombin times were averaged for each day and mean times were compared from each study day to baseline using repeated measures ANOVA., Results: There was no statistical difference between mean prothrombin time at baseline and any day tested during juice administration., Conclusions: Cranberry juice (240 ml twice daily for 1 week) did not alter the pharmacodynamics of warfarin in patients.

Few published reports have suggested a substantial interaction between cranberry juice and warfarin, although a definite link could not be established. We encountered a patient taking stable doses of warfarin who developed major bleeding and high INR soon after starting daily cranberry juice. No other identifiable reasons for the high INR were apparent. The patient resumed his usual dose of warfarin after stopping the juice. This case suggests a definite relationship between cranberry juice and warfarin.