The Effect of Furosemide and Bumetanide on Warfarin Metabolism and Anticoagulant Response

Abstract

In a study of 11 normal subjects who received either furosemide or bumetanide, response to warfarin was unaffected by either diuretic. The mean prothrombin times after a single oral dose of 50 mg warfarin were 18.8 .+-. 0.7 s before and 19.6 .+-. 1.7 s during furosemide administration, and 18.3 .+-. 1.4 s before and 19.7 .+-. 1.3 s during bumetanide administration. Mean plasma warfarin half-lives were 43.2 .+-. 2.8 h before and 37.8 .+-. 1.7 h during furosemide treatment and 39.9 .+-. 9.5 h before and 37.4 .+-. 2.4 h during bumetanide treatment. Hypoprothrombinemic responses, plasma warfarin concentrations and warfarin half-lives were not significantly influenced by treatment with either diuretic. Both loop diuretics furosemide and bumetanide can be safely administered during warfarin anticoagulant therapy without risk of clinically significant interaction.