Retrospective Investigation of the Drug Interaction between Warfarin Potassium and Bucolome, and Pharmaceutical Advisory

Because of its drug interaction with warfarin K, bucolome is used to reduce the dose of warfarin K. We retrospectively investigated the prescription of warfarin K and bucolome in our hospital from January 2000 to June 2002, based on data from the thrombo test as an indicator of the effects. The total number of patients who were prescribed warfarin K was 654 (mean age, 62.7), and 55 (mean age, 62.8) of those were prescribed both warfarin K and bucolome during the period under investigation. All patients given bucolome were administered warfarin K. Bucolome was discontinued in nine patients, while it was added in five patients. The dose of warfarin K was changed when the bucolome therapy started or stopped in 11 patients, and the same dose of warfarin K was prescribed in three patients upon the discontinuation of bucolome. The doses of warfarin K in the 11 patients who started or stopped bucolome were reduced by more than 50% without any significant change in the thrombo test findings. However, the thrombo level increased in the other three patients and several thrombo tests were subsequently necessary to determine the proper dosage of warfarin K. Pharmacists must therefore monitor not only the dose of warfarin K but also that of any concurrently administered drugs interacting with warfarin K, as well as any previously prescribed medications. Pharmaceutical instruction to the patients, especially in clinical departments unfamiliar with warfarin use, is also essential.