Warfarin with Glucosamine Interaction Details
Brand Names Associated with Warfarin
- Coumadin®
- Jantoven®
- Warfarin
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Nov 07, 2023
Interaction Effect
Elevations of International Normalized Ratio serum values and potentiation of anticoagulant effects
Interaction Summary
A review of the literature, MedWatch case reports, and the World Health Organization (WHO) adverse drug reactions database indicate that the use of warfarin and glucosamine may cause an increase in INR. Glucosamine use in patients stabilized on warfarin therapy may increase the INR value and potentially increase the risk for bleeding. The addition of chondroitin sulfate-glucosamine combination to a stable dose regimen of warfarin appeared to magnify the anticoagulant effects of warfarin, in a 2 case reports . If concomitant therapy is necessary, the patient's INR should be more closely monitored .
Severity
Moderate
Onset
Delayed
Evidence
Probable
How To Manage Interaction
Warfarin dosage adjustments may be required when glucosamine therapy is initiated or modified during concomitant treatment. During concurrent treatment, closely monitor the prothrombin time (PT) or International Normalized Ratio (INR).
Mechanism Of Interaction
Unknown
Literature Reports
A) A 71-year-old patient with atrial fibrillation maintained for 5 years on warfarin 7.5 mg/day and glucosamine hydrochloride/chondroitin sulfate 500 mg/400 mg twice a day for arthritis experienced an increase in INR following an increase in glucosamine/chondroitin dosing to 1500 mg/1200 mg twice daily. Prior to this change, his INR was stable at 2.3. Approximately 3 weeks later, the INR measured 3.9, without any changes to diet or other medications. Despite a decrease in glucosamine/chondroitin to 750 mg/600 mg/day, 16 days later the INR was 4.7. The patient discontinued the supplement, warfarin was decreased to 7.5 mg every other day alternating with 3.75 mg every other day, and an INR measured 16 days later was 2.6. A review of the literature, MedWatch case reports, and the World Health Organization (WHO) adverse drug reactions database indicated that the use of warfarin and glucosamine may cause an increase in INR .
B) The concurrent use chondroitin sulfate-glucosamine combination and warfarin appeared to magnify the anticoagulant effects of warfarin. In a case report, a 69-year-old man had received warfarin 47.5 milligrams (mg) weekly and maintained a therapeutic International Normalized Ratio (INR; between 2 and 3) over a 4 month period preceding his beginning self-treatment with a chondroitin sulfate-glucosamine combination product (CG; chondroitin sulfate 400 mg and glucosamine hydrochloride 500 mg with manganese ascorbate). Compared with a baseline INR of 2.58 (before starting CG), the patient's INR ascended to 4.52 within 4 weeks of starting CG treatment. The patient continued to ingest CG and warfarin dose was reduced to 40 mg weekly, 2 weeks after which his INR declined to 2.15. In the presence of continued use of CG, the patient's INR continued to stay within the targeted range on the lower dose over 3 months of follow up .
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.
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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.