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Increased warfarin requirements in a patient with chronic hepatitis C infection receiving sofosbuvir and ribavirin

Daisy Peterson1, Amy Van Ermen2

  • 1Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, WI. daisy.peterson@va.gov.

American Journal of Health-System Pharmacy : AJHP : Official Journal of the American Society of Health-System Pharmacists
|June 10, 2017
PubMed

Insights

Hepatitis C virus (HCV) treatment with sofosbuvir and ribavirin may increase warfarin dosage requirements. Patients on warfarin anticoagulation need close monitoring for International Normalized Ratio (INR) fluctuations during HCV therapy.

Area of Science:

  • Pharmacology
  • Hepatology
  • Infectious Diseases

Background:

  • Warfarin is a common anticoagulant for atrial fibrillation and stroke prevention.
  • Hepatitis C virus (HCV) infection requires treatment with direct-acting antivirals.
  • Drug-drug interactions between HCV treatments and anticoagulants can impact patient management.

Observation:

  • A patient on stable warfarin therapy required increased dosage during treatment for HCV genotype 2.
  • Warfarin dose increased progressively to maintain therapeutic International Normalized Ratio (INR) levels.
  • INR values normalized, and warfarin dosage decreased post-treatment, but higher maintenance doses were needed long-term.

Findings:

  • Sofosbuvir and ribavirin treatment necessitated a significant increase in weekly warfarin dosage.
  • Subtherapeutic INR levels were observed during the HCV treatment course.
  • Long-term monitoring revealed sustained higher warfarin requirements post-treatment.

Implications:

  • Clinicians should anticipate and monitor for altered warfarin requirements in patients receiving sofosbuvir and ribavirin.
  • Close INR monitoring is crucial during and after HCV treatment to prevent thromboembolic events.
  • This interaction highlights the importance of comprehensive medication review in patients with co-existing conditions.
Abstract

Keywords:
CYP450drug interactionhepatitis Cribavirinsofosbuvirwarfarin

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