Interaction between acetaminophen and warfarin in adults receiving long-term oral anticoagulants: a randomized controlled trial

@article{Zhang2010InteractionBA,
  title={Interaction between acetaminophen and warfarin in adults receiving long-term oral anticoagulants: a randomized controlled trial},
  author={Qian Zhang and Claire Bal-dit-Sollier and Ludovic Drouet and Guy Simoneau and Jean Claude Alvarez and Sandrine Pruvot and Romain Aubourg and Natacha Berge and Jean François Bergmann and St{\'e}phane Mouly and Isabelle Mah{\'e}},
  journal={European Journal of Clinical Pharmacology},
  year={2010},
  volume={67},
  pages={309-314}
}
PurposeWe investigated whether acetaminophen, given at 2 g/day and 3 g/day might potentiate the anticoagulant effect of warfarin.MethodsForty-five patients on stable warfarin therapy, enrolled in this prospective, randomized, parallel (three arms), placebo-controlled study, received a 10-day regimen of acetaminophen (2 g/day or 3 g/day) or placebo.ResultsThe mean maximal INR increase was 0.70 ± 0.49 and 0.67 ± 0.62 in patients receiving acetaminophen at 2 g/day and 3 g/day, respectively (P = 0… 
How safe is acetaminophen use in patients treated with vitamin K antagonists? A systematic review and meta-analysis.
TLDR
Patients treated concomitantly with VKA and acetaminophen should be monitored more regularly for possible VKA dosage adjustment, with a dose dependent relationship.
Warfarin and acetaminophen interaction: a summary of the evidence and biologic plausibility.
TLDR
A 66-year-old woman who receives warfarin for prevention of systemic embolization in the setting of hypertension, diabetes, and atrial fibrillation is wondering if her acetaminophen use is contributing to her loss of INR control, and does this interaction place her at increased risk of warFarin-related complications.
Analgesic use before and after oral anticoagulant initiation—a population-based study in Finland
TLDR
The use of NSAIDs decreases extensively among warfarin initiators which is encouraging, however, the use ofNSAIDs increases among rivaroxaban and dabigatran initiators, which is a concern as the bleeding risk may increase due to potential pharmacodynamic interactions.
Population Impact of Drug Interactions with Warfarin: A Real-World Data Approach.
TLDR
Clinically potentially important interactions were observed in several study drugs, although confirmed, had little impact after adjusting for standard INR variability in the general population of warfarin users.
Frailty and Co-Prescribing of Potentially Interacting Drugs in New Users of Warfarin
TLDR
The overall frequency of potential drug interactions was moderate and frail patients were not exposed to warfarin drug interactions more often than non-frail patients.
Concurrent use of tramadol and oral vitamin K antagonists and the risk of excessive anticoagulation: a register-based nested case–control study
TLDR
Caution is advised when using tramadol in patients using VKA, and if possible, an alternative pain-medication should be used, as the result is potentially confounded by concomitant paracetamol use and the presence of acute illness.
Comparison of Prothrombin Time and Aspartate Aminotransferase in Predicting Hepatotoxicity After Acetaminophen Overdose
TLDR
Initial AST performed better than the initial PT for predicting hepatic injury in this series of patients with APAP overdose, and neither test performed similarly for predicting a composite endpoint of death or liver transplant.
Beyond warfarin: the new generation of oral anticoagulants and their implications for the management of dental patients.
TLDR
The pharmacologic properties and medical uses of 2 novel types of oral anticoagulants approved for use in the USA are described, including potential interactions with drugs commonly used or prescribed in the course of dental treatment.
The Risk of Drug-Drug Interactions with Paracetamol in a Population of Hospitalized Geriatric Patients
TLDR
A large majority of the patients in this study received treatment with paracetamol, and six patients were evaluated as having abnormal biochemical values or were experiencing clinical incidents during their hospitalization potentially related to the identified potential drug-drug interactions.
Adverse drug reactions and drug–drug interactions with over-the-counter NSAIDs
TLDR
This review discusses some of the most clinically relevant DDIs reported with NSAIDs based on major sites of ADRs and classes of medication, with a focus on OTC ibuprofen, for which the most data are available.
...
1
2
3
4
...

References

SHOWING 1-10 OF 20 REFERENCES
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.
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.
Acetaminophen and other risk factors for excessive warfarin anticoagulation.
TLDR
The data suggest that acetaminophen is an underrecognized cause of overanticoagulation in the outpatient setting, and increased monitoring of INR values when such risk factors are present or modification of the risk factors themselves should reduce the frequency of dangerously high levels of anticoagulations.
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.
Effect of Oral Anticoagulant Treatment on Markers for Calcium and Bone Metabolism
TLDR
It is concluded that bone turnover remained unaltered, which is indicative of an unchanged rate of bone loss.
Association of polymorphisms in the cytochrome P450 CYP2C9 with warfarin dose requirement and risk of bleeding complications
TLDR
YP2C9 genotyping may identify a subgroup of patients who have difficulty at induction of warfarin therapy and are potentially at a higher risk of bleeding complications.
Paracetamol (acetaminophen) warfarin interaction: NAPQI, the toxic metabolite of paracetamol, is an inhibitor of enzymes in the vitamin K cycle.
TLDR
The potentiation of the oral anticoagulant effect by paracetamol is likely to result from NAPQI-induced inhibition of enzymes of the vitamin K cycle, particularly VKD-carb.
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.
Drug Interactions with Paracetamol
TLDR
Paracetamol (acetaminophen) is one of the most commonly used analgesic antipyretic drugs worldwide, and it is widely available by prescription and over the counter (OTC) and these are unlikely to be important at therapeutic doses.
Systematic overview of warfarin and its drug and food interactions.
TLDR
The consistency of reports of interactions with azole antibiotics, macrolides, quinolones, nonsteroidal anti-inflammatory drugs, including selective cyclooxygenase-2 inhibitors, selective serotonin reuptake inhibitors, omeprazole, lipid-lowering agents, amiodarone, and fluorouracil suggests that coadministration with warfarin should be avoided or closely monitored.
...
1
2
...