Express Scripts FoundationResearch & Consumerology
Warfarin and Antimicrobials: 28% of Patients Could Have
Serious Drug-Drug Interactions
Published: January 28, 2010
By: Lane MA, Devine ST, McDonald JR. 47th Annual Infectious Diseases Society of America Meeting, Philadelphia PA, October 2009
ST. LOUIS – A group of St. Louis researchers and physicians recently examined the prescribing patterns between warfarin and antimicrobials to determine the risk of important drug-drug interactions. What did they find? These interactions were possibly more frequent than many physicians and pharmacists may have realized.
Warfarin interacts with many antimicrobials, creating the potential for serious bleeding events. However the extent of this risk is unknown. Research conducted by Express Scripts Director of Health Services Research, Scott Devine, Washington University researcher Dr. Jay McDonald and Dr. Michael Lane of the St. Louis VA Medical Center found that compared to those not taking warfarin, those taking warfarin were less likely to be taking antimicrobials that interact with warfarin. But, the rate of co-prescribing interacting antimicrobials among those taking warfarin was still high at 28%. While concurrent and retrospective DUR programs can lessen drug risk for patients taking warfarin, this research should be noted by physicians and pharmacists.
