Effect of Acetaminophen on International Normalized Ratio in Patients Receiving Warfarin Therapy

@article{Hughes2011EffectOA,
  title={Effect of Acetaminophen on International Normalized Ratio in Patients Receiving Warfarin Therapy},
  author={Gregory J. Hughes and Priti N. Patel and Neera Saxena},
  journal={Pharmacotherapy: The Journal of Human Pharmacology and Drug Therapy},
  year={2011},
  volume={31}
}
Warfarin is known to have extensive interactions with many classes of drugs. The literature suggesting a relevant interaction between acetaminophen and warfarin is inconsistent. Considering the ubiquitous use of acetaminophen, a review of the effects on international normalized ratio (INR) in patients taking warfarin was necessary. Thus, we performed a search of the PubMed (1966‐November 2010) and International Pharmaceutical Abstracts (1970‐November 2010) databases to review the available… 

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References

SHOWING 1-10 OF 24 REFERENCES

Warfarin‐Acetaminophen Drug Interaction Revisited

TLDR
Evidence is found that acetaminophen may potentiate the effect of warfarin by a mechanism that has yet to be elucidated, which means it should be the analgesic and antipyretic of choice in patients taking warfarins, as long as excessive amounts and prolonged administration are avoided.

Enzymatic Shunting: Resolving the Acetaminophen‐Warfarin Controversy

TLDR
The discrepant observations in the literature regarding the clinical significance of the acetaminophen‐warfarin interaction may be resolved if the hepatic enzyme activity of CYP1A2 and 3A4 is enhanced relative to CYP2E1 and the nonoxidative pathways of glucuronidation and sulfation responsible foracetaminophen metabolism.

Acetaminophen Causes an Increased International Normalized Ratio by Reducing Functional Factor VII

TLDR
An isolated, small rise in INR is common after acetaminophen poisoning without hepatic injury and appears to be caused by inhibition of Vitamin K–dependent activation of coagulation factors, which suggests a possible mechanism for the observed interaction betweenacetaminophen and warfarin.

Potentiation of warfarin anticoagulation by acetaminophen.

TLDR
A patient who was receiving warfarin was admitted to a hospital with bleeding closely associated with concurrent acetaminophen ingestion, and patients receiving this oral anticoagulant are frequently told that they can safely use this analgesic-antipyretic in place of aspirin.

The Effects of Acetaminophen on Pharmacokinetics and Pharmacodynamics of Warfarin

TLDR
The urinary excretion pattern of acetaminophen and its metabolites was not significantly altered over its course of administration, and the (R)‐ and (S)‐enantiomers of warfarin exhibited significantly different pharmacokinetic properties.

Warfarin and Acetaminophen Interaction

TLDR
Patients receiving warfarin should be counseled to have their INR monitored more frequently when starting acetaminophen at dosages exceeding 2 g/day, as changes in INR of this magnitude with the addition of another drug during stable anticoagulation therapy suggest a drug interaction.

Adverse interaction of warfarin and paracetamol: evidence from a post-mortem study

TLDR
This study supports the clinical evidence suggesting that warfarin-paracetamol interactions may create significant life-threatening conditions and accentuates the significant role post-mortem database research can have in improving drug safety.

Interaction between paracetamol and warfarin in patients: a double-blind, placebo-controlled, randomized study.

TLDR
It is suggested that paracetamol at 4 g daily (a dose higher than that used in clinical practice) potentiates the anticoagulant response produced by warfarin and interfere with enzymes involved in vitamin K-dependent coagulation factor synthesis.

Potentiation of the anticoagulant effect of warfarin.

TLDR
A 63-year-old woman with longstanding rheumatoid arthritis was receiving warfarin therapy for an aortic valve replacement and remained stable at 4-4.5 mg per day with no significant bleeding or thrombotic episodes.

Pharmacology and management of the vitamin K antagonists: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition).

TLDR
This article describes the antithrombotic effect of the VKAs, the monitoring of anticoagulation intensity, and the clinical applications of VKA therapy and provides specific management recommendations.