Enhancement of anticoagulant effect of warfarin in a bladder cancer patient during treatment with gemcitabine and cisplatin

Abstract

A 64-year-old man had a mass at the left obturator lymph node region in the pelvis and was diagnosed with bladder cancer recurrence with deep vein thrombosis. After the initiation of anticoagulant therapy with warfarin for deep vein thrombosis, the patient underwent two cycles of the combination of gemcitabine and cisplatin and was concomitantly administered aprepitant, granisetron, and dexamethasone. Although the prothrombin time–international normalized ratio was 1.89 before initiation of the chemotherapy, it increased to 4.17 on day 5 of the first chemotherapy. After discontinuation of warfarin, it decreased to 1.01. During the second cycle of chemotherapy, a similar transient increase in prothrombin time–international normalized ratio was observed. We should be aware of the possibility of prothrombin time–international normalized ratio being increased transiently when the combination of gemcitabine and cisplatin is applied to bladder cancer patients taking warfarin. The interaction between warfarin and cisplatin and/or dexamethasone might be the main cause of the prothrombin time–international normalized ratio elevation.