Warfarin with Lactulose Interaction Details


Brand Names Associated with Warfarin

  • Coumadin®
  • Jantoven®
  • Warfarin

Brand Names Associated with Lactulose

  • Cholac®
  • Constilac® Syrup
  • Constulose®
  • Enulose®
  • Evalose® Syrup
  • Generlac®
  • Heptalac®
  • Kristalose®
  • Lactulose
  • Laxilose®
  • Portalac®

Medical Content Editor
Last updated Nov 07, 2023


Curious for more information about this interaction?

Ask our pharmacists directly!

Reach out to us

Interaction Effect

Elevated International Normalized Ratio serum values with potentiation of anticoagulation effects


Interaction Summary

Coadministration of lactulose with either acenocoumarol or phenprocoumon (coumarin derivatives related to warfarin) resulted in a significantly higher risk of excessive anticoagulation in patients receiving prophylactic anticoagulation therapy (adjusted relative risk =3.4).


Severity

Moderate


Onset

Unspecified


Evidence

Probable


How To Manage Interaction

In patients receiving oral anticoagulant therapy with warfarin, the prothrombin time ratio or INR (international normalized ratio) should be closely monitored with the addition and withdrawal of treatment with lactulose, and should be reassessed periodically during concurrent therapy. Adjustments of the warfarin dose may be necessary in order to maintain the desired level of anticoagulation.


Mechanism Of Interaction

Reduced intestinal absorption of vitamin K


Literature Reports

A) Coadministration of lactulose with the coumarin-derivatives acenocoumarol or phenprocoumon resulted in a significantly higher risk of excessive anticoagulation in patients receiving prophylactic anticoagulation therapy. In a population-based retrospective cohort study, patients receiving anticoagulation therapy with acenocoumarol or phenprocoumon (n=1124) were evaluated for a correlation between laxative use and the incidence of excessive anticoagulation (indicated by an International Normalized Ratio (INR) equal to or greater than 6.0). Of all patients studied, 351 developed an INR above 6.0, and 51 of this group (15%) had used a laxative on the index date. Among 5 types of laxatives used by the high INR group, concomitant use of lactulose with acenocoumarol or phenprocoumon was most strongly associated with a state of over-anticoagulation. The adjusted relative risk (RR) for over-anticoagulation associated with lactulose-acenocoumarol (or phenprocoumon) co-therapy was 3.4 (95% confidence interval (CI): 2.2, 5.3). There was no clear lactulose dose-effect relationship. When stratified by duration of laxative exposure, the use of lactulose initially conferred a protective effect against over-anticoagulation when used for less than 27 days (RR=0.5, 95% CI: 0.3, 0.8). However, this effect was reversed for lactulose-acenocoumarol (or phenprocoumon) co-treatment duration in excess of 27 days; for days 28 through 97, over-anticoagulation RR was 1.7 (95% CI: 0.9, 3.0) and for greater than 98 days duration, RR was 2.1 (95% CI: 1.2, 3.7) .

Warfarin Overview

  • Warfarin is used to prevent blood clots from forming or growing larger in your blood and blood vessels. It is prescribed for people with certain types of irregular heartbeat, people with prosthetic (replacement or mechanical) heart valves, and people who have suffered a heart attack. Warfarin is also used to treat or prevent venous thrombosis (swelling and blood clot in a vein) and pulmonary embolism (a blood clot in the lung). Warfarin is in a class of medications called anticoagulants ('blood thinners'). It works by decreasing the clotting ability of the blood.

See More information Regarding Warfarin

Lactulose Overview

  • Lactulose is a synthetic sugar used to treat constipation. It is broken down in the colon into products that pull water out from the body and into the colon. This water softens stools. Lactulose is also used to reduce the amount of ammonia in the blood of patients with liver disease. It works by drawing ammonia from the blood into the colon where it is removed from the body.

  • This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

See More information Regarding Lactulose

Return To Our Drug Interaction Homepage


Feedback, Question Or Comment About This Information?

Ask , our medical editor, directly! He's always more than happy to assist.


Definitions

Severity Categories

Contraindicated

These drugs, generally, should not be used together simultaneously due to the high risk of severe adverse effects. Combining these medications can lead to dangerous health outcomes and should be strictly avoided unless otherwise instructed by your provider.


Major

This interaction could result in very serious and potentially life-threatening consequences. If you are taking this drug combination, it is very important to be under close medical supervision to minimize severe side effects and ensure your safety. It may be necessary to change a medication or dosage to prevent harm.


Moderate

This interaction has the potential to worsen your medical condition or alter the effectiveness of your treatment. It's important that you are monitored closely and you potentially may need to make adjustments in your treatment plan or drug dosage to maintain optimal health.


Minor

While this interaction is unlikely to cause significant problems, it could intensify side effects or reduce the effectiveness of one or both medications. Monitoring for changes in symptoms and your condition is recommended, and adjustments may be made if needed to manage any increased or more pronounced side effects.


Onset

Rapid: Onset of drug interaction typically occurs within 24 hours of co-administration.

Delayed: Onset of drug interaction typically occurs more than 24 hours after co-administration.


Evidence

Level of documentation of the interaction.

Established: The interaction is documented and substantiated in peer-reviewed medical literature.

Theoretical: This interaction is not fully supported by current medical evidence or well-documented sources, but it is based on known drug mechanisms, drug effects, and other relevant information.


How To Manage The Interaction

Provides a detailed discussion on how patients and clinicians can approach the identified drug interaction as well as offers guidance on what to expect and strategies to potentially mitigate the effects of the interaction. This may include recommendations on adjusting medication dosages, altering the timing of drug administration, or closely monitoring for specific symptoms.

It's important to note that all medical situations are unique, and management approaches should be tailored to individual circumstances. Patients should always consult their healthcare provider for personalized advice and guidance on managing drug interactions effectively.


Mechanism Of Interaction

The theorized or clinically determined reason (i.e., mechanism) why the drug-drug interaction occurs.


Disclaimer: The information provided on this page is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional regarding your specific circumstances and medical conditions.

Where Does Our Information Come From?

Information for our drug interactions is compiled from several drug compendia, including:

The prescribing information for each drug, as published on DailyMED, is also used. 

Individual drug-drug interaction detail pages contain references specific to that interaction. You can click on the reference number within brackets '[]' to see what reference was utilized.

The information posted is fact-checked by HelloPharmacist clinicians and reviewed quarterly.