A Comparative Study Between the Effect of Hydrochlorothiazide and Furosemide on the Anticoagulant Activity of Warfarin


Background:It has been widely reported that diuretics therapy affect serum calcium level which is in turn may affect the coagulation pathways and thereby could affect the activity of anticoagulation therapy. This study was undertaken to evaluate the effect of simultaneous diuretic intake on the anticoagulant activity of warfarin.Patients and Method: Twenty patients enrolled in this study divided to two groups, group 1 ( N=10 patients) were taking furosemide 80mg/day plus warfarin 3 mg /day. Group 2 (N=10 patients) were taking hydrochlorothiazide 50 mg /day plus warfarin 3 mg/day. Blood samples were taken from each patient and used for measurement of serum calcium level, prothrombine time(PT) and international normalized ratio(INR). Results: It has been found that there was a significant reduction (P<0.01) in calcium concentration in patients taking furosemide with warfarin (group 1) with respect to those who were taking hydrochlothiazide in addition to warfarin(group 2). On the other hand both PT and INR weresignificantly increased in patients with group 1 with respect to those in group 2.Conclusions:It may be concluded from this study that the combination of hydrochlorothiazide with warfarin may decrease the anticoagulant activity of the later.