Warfarin with Bismuth Subsalicylate Interaction Details
Brand Names Associated with Warfarin
- Coumadin®
- Jantoven®
- Warfarin
Brand Names Associated with Bismuth Subsalicylate
- Bismusal®
- Bismuth Subsalicylate
- Kaopectate®
- Peptic Relief®
- Pepto-Bismol®
- Pink Bismuth®
- Stomach Relief®
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Nov 07, 2023
Interaction Effect
An increased risk of bleeding
Interaction Summary
Although there are no reports of a warfarin-bismuth subsalicylate interaction in the literature, there appears to be potential for such an interaction. The salicylate moiety of bismuth subsalicylate is almost completely absorbed, with 95% of salicylate in each dose being recovered in the urine after 72 hours. Concurrent use of warfarin and salicylates should be avoided.
Severity
Moderate
Onset
Delayed
Evidence
Theoretical
How To Manage Interaction
In patients receiving oral anticoagulant therapy with warfarin, the prothrombin time ratio or international normalized ratio (INR) should be closely monitored with the addition and withdrawal of treatment with bismuth subsalicylate, 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. People taking oral anticoagulants should be cautioned about the use of Pepto-Bismol(R), especially in the large dosages associated with the treatment of traveler's diarrhea.
Mechanism Of Interaction
Hypoprothrombinemia, displacement of warfarin from protein binding sites
Literature Reports
A) Pepto-Bismol(R) contains absorbable salicylates in the form of bismuth subsalicylate 1.75% or 0.52 g/30 mL, a common dosage which is recommended to be repeated every one-half to one hour .
B) Oral administration of 60 mL of Pepto-Bismol(R) to 6 normal adult subjects caused peak plasma levels of 40 mcg/mL (290 mcmol/L) which are comparable to serum levels of aspirin after analgesic doses. Ninety percent of the ingested dose (of the salicylate moiety) was recovered in the urine either in the unaltered form or as metabolites .
C) Salicylates in large doses will decrease plasma prothrombin levels and may also displace coumarin anticoagulants from plasma protein . There appears to be a dose-related effect of salicylates on anticoagulants. In doses of 2 g/day salicylates increased hypoprothrombinemia in only some patients. In doses of 3 to 4 g/day, they enhanced the hypoprothrombinemic effect of the anticoagulants in almost all patients .
D) Small doses will decrease platelet function . This will cause a further inhibition of the clotting process, with a resultant increased tendency to bleed .
Warfarin Overview
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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.
Bismuth Subsalicylate Overview
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Bismuth subsalicylate is used to treat diarrhea, heartburn, and upset stomach in adults and children 12 years of age and older. Bismuth subsalicylate is in a class of medications called antidiarrheal agents. It works by decreasing the flow of fluids and electrolytes into the bowel, reduces inflammation within the intestine, and may kill the organisms that can cause diarrhea.
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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.