BACKGROUND: The cephalosporin class has been associated with an increased risk of bleeding among elderly patients receiving warfarin.
Urinary tract infections (UTI) are the most prevalent infection in elderly patients.
OBJECTIVE: To determine the extent of interaction between antibiotics used in the treatment of UTI, particularly specific cephalosporins and warfarin.
METHODS: A retrospective chart review was conducted on chronic warfarin patients with a diagnosis of UTI treated with ceftriaxone, a first-generation cephalosporin, penicillin, or ciprofloxacin. The primary outcome was the comparison of the extent of international normalized ratio (INR) change from baseline between each antibiotic group.
RESULTS: The ceftriaxone group was found to have a statistically significant higher peak INR value compared to all other studied antibiotics (ceftriaxone: 3.56, first-generation cephalosporins: 2.66, penicillins: 2.98, ciprofloxacin: 2.3; P = .004), a statistically significant greater extent of change in INR value (+1.19, +0.66, +0.8, +0.275; P = .006), and a statistically significant greater percentage change in INR value when compared to ciprofloxacin (54.4% vs 12.7%; P = .037).
CONCLUSION: Ceftriaxone interacts with warfarin to increase a patient's INR value more than other commonly administered antibiotics for UTI treatment. Other antibiotics should be preferred for UTI treatment in patients on warfarin.
Written by:
Saum LM, Balmat RP. Are you the author?
Department of Pharmacy Practice, Butler University College of Pharmacy and Health Sciences, Indianapolis, IN, USA; Department of Pharmacy, St Vincent Hospital, Indianapolis, IN, USA; Department of Pharmacy, Cleveland Clinic, Cleveland, OH, USA.
Reference: J Pharm Pract. 2014 Aug 3. pii: 0897190014544798.
doi: 10.1177/0897190014544798
PubMed Abstract
PMID: 25092605