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Warfarin potassium (Wf) interacts with a wide range of drugs and occasionally causes severe bleeding.We report the case of a 60-year-old female patient on Wf therapy who received 5 courses of cancer chemotherapy with doxorubicin,paclitaxel,and cisplatin.The Wf dose had to be reduced immediately after the chemotherapy due to an increase in international normalized ratio (INR).We then steadily increased the Wf dose till it had reached the previous level,which took almost 11 days from the time of receiving the anti-cancer agents.Although we could not determine which agent was interacting with Wf to cause the rise in INR in this case,we feel that attention must be paid to Wf drug-interactions for chemotherapy agents that have not previously been reported to interact with Wf in order to avoid the risk of bleeding.Therefore,there is a need for pharmacists to check medicines prescribed to patientsundergoingcancerchemotherapybyothermedicaldepart-ments and other medical clinics,especially for outpatients.

To evaluate combination therapy with warfarin potassium (WF) and bucolome (BUC),we assigned patients on warfarin potassium (WF) at Kochi University Medical School Hospital to a group also receiving BUC (BUC-combination group) and a group not receiving BUC (non-combination group),and compared the WF doses and TT values.In each patient,we investigated the doses of WF before and after the start or discontinuation of combination therapy with BUC.There was no significant difference in TT values between the two groups.However,the WF dose in the BUC-combination group was significantly lower than that in the non-combination group.BUC was therefore useful for maintaining anticoagulation activity and decreasing the dose of WF.Furthermore,there was a correlation between the doses of WF before and after the start or discontinuation of combination therapy with BUC in each patient.Based on the regression line obtained using WF doses,in the presence and absence of BUC,the subsequent dose of WF could be predicted at the start or discontinuation of combination therapy with BUC,suggesting that it would be useful in anticoagulation control.

A very important instruction given to patients prescribed warfarin potassium(Wf)is to seek urgent medical help if bleeding occurs.However,it is a good idea for patients to seek help and ensure that they are being adequately treated with vitamin K(VK)injection before bleeding actually occurs.We retrospectively investigated the causes of enhanced international normalized ratio(INR)in outpatients prescribed Wf and using VK injection from 2000-2004.Owing to a higher INR,nine outpatients(mean age : 72.3)were injected with VK in this period.Two of them were injected with VK at the first consultation after hospitalization during which Wf therapy had been started,and the remaining 7 had appetite loss due to various causes,exacerbation of their underlying disease,overwork or drinking.Therefore,patients prescribed Wf should be instructed to seek immediate medical help when they have appetite loss of various causes before actual bleeding occurs and pay attention to bleeding,especially soon after the dose of Wf is determined.