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Ciprofloxacin interaction with sodium warfarin: a potentially dangerous side effect
1Yale University School of Medicine, New Haven, CT.
The American Journal of Emergency Medicine
|November 1, 1991
Abstract:
Ciprofloxacin, a quinolone antibiotic which exhibits minimal side effects and has broad antimicrobial spectrum, is being used frequently to treat various infections. A patient is reported who had previously maintained a stable prothrombin time on Coumadin for 5 years, and who exhibited a marked prolongation of prothrombin time when placed on ciprofloxacin for gastroenteritis.
Insights
Ciprofloxacin, a broad-spectrum antibiotic, can interact with warfarin (Coumadin), significantly prolonging prothrombin time. This case highlights a critical drug interaction requiring careful patient monitoring.
Area of Science:
- Pharmacology
- Infectious Diseases
- Internal Medicine
Background:
- Ciprofloxacin is a widely prescribed fluoroquinolone antibiotic known for its broad antimicrobial spectrum and generally favorable safety profile.
- Warfarin (Coumadin) is a common anticoagulant medication requiring regular monitoring of prothrombin time (PT) to maintain therapeutic anticoagulation.
- Drug interactions with ciprofloxacin can alter the efficacy and safety of concurrently administered medications.
Observation:
- A patient with a history of stable prothrombin time on warfarin for five years was initiated on ciprofloxacin for gastroenteritis.
- During ciprofloxacin therapy, the patient experienced a marked and unexpected prolongation of their prothrombin time.
Findings:
- The concurrent use of ciprofloxacin and warfarin led to a significant increase in the patient's prothrombin time.
- This indicates a potential pharmacokinetic or pharmacodynamic interaction between the two drugs.
Implications:
- Clinicians should be vigilant for potential drug interactions between ciprofloxacin and warfarin.
- Close monitoring of prothrombin time is essential in patients receiving both medications to prevent bleeding complications.
- This case underscores the importance of considering drug interactions even in patients with previously stable anticoagulation.