Warfarin with Oxandrolone Interaction Details
Brand Names Associated with Warfarin
- Coumadin®
- Jantoven®
- Warfarin
Brand Names Associated with Oxandrolone
- Oxandrin®
- Oxandrolone
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Nov 07, 2023
Interaction Effect
Increased anticoagulant response and increased risk of bleeding
Interaction Summary
Anabolic steroids may increase the anticoagulant response to oral anticoagulants, such as anisindione. In a multi-dose study of healthy subjects (n=15), concurrent treatment with warfarin and oxandrolone produced clinically significant increases in the mean half-life and area under the concentration-time curve (AUC) of the isomeric metabolites of warfarin; this required substantial reductions in warfarin dose in order to maintain a therapeutic target level (1.5) in International Normalized Ratio values . A number of case reports have demonstrated that coadministration of oral anticoagulants and 17-alkylated androgens (oxandrolone, fluoxymesterone, oxymetholone, methyltestosterone, methandrostenolone, stanozolol) has resulted in a prolonged prothrombin time and hemorrhages .
Severity
Major
Onset
Delayed
Evidence
Probable
How To Manage Interaction
Avoid this combination when possible. If used, the prothrombin time ratio or International Normalized Ratio (INR) should be closely monitored with the addition and withdrawal of treatment with oxandrolone, and should be regularly and carefully reassessed during concurrent therapy. Adjustments of the warfarin dose may be necessary in order to maintain the desired level of anticoagulation.
Mechanism Of Interaction
Unknown
Literature Reports
A) Anabolic steroids have been well documented to cause important interactions with dicumarol. The anabolic steroids enhance dicumarol's anticoagulant activity perhaps through reductions in clotting factor formation and increased clotting factor degradation. The 17-alpha-alkylated steroids (oxandrolone, fluoxymesterone, oxymetholone, methyltestosterone, methandrostenolone, stanozolol) appear to be more likely to induce this reaction than the non-substituted steroids .
B) A mean increase in R-warfarin half-life occurred in patients receiving warfarin and oxandrolone concomitantly. In a multidose study, 16 healthy patients were administered oxandrolone 5 or 10 mg twice daily while also receiving warfarin. A mean increase in R-warfarin half-life from 35.2 to 79.2 hours occurred as did a mean increase in the S-warfarin half life. A 5.5 fold decrease in mean warfarin dose from 6.13 mg daily to 1.13 mg daily was necessary to maintain a target INR of 1.5. INR must be closely monitored for up to 4 weeks or until a stable INR has been achieved. Once oxandrolone therapy has been completed a retitration of the warfarin dose is necessary .
C) Concurrent treatment with warfarin and oxandrolone produced clinically significant increases in the mean half-life and area under the concentration-time curve (AUC) of the isomeric metabolites of warfarin. In a multidose study, healthy subjects (n=15) received concomitant treatment with oxandrolone 5 or 10 milligrams (mg) twice daily and warfarin (mean daily dose of 6.13 mg). For S-warfarin, the mean half-life increased from 26 to 48 hours and AUC increased from 4.55 nanograms x hour/milliliter (ng x hr/mL) to 12.08 ng x hr/mL); similar increases were observed for the R-warfarin isomer (actual values not available). Microscopic hematuria was confirmed in 9 patients, and 1 patient exhibited gingival bleeding. A 5.5-fold decrease in mean daily warfarin dose was required (from 6.13 mg/day to 1.13 mg/day) in order to maintain a target International Normalization Ratio of 1.5 .
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.
Oxandrolone Overview
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Oxandrolone is used with a diet program to cause weight gain in people who have lost too much weight due to surgery, injury, chronic (long-lasting) infections, trauma, or who are underweight for unknown reasons. Oxandrolone is also used to treat bone pain in people with osteoporosis (a condition in which the bones become thin and weak and break easily) and to prevent certain side effects in people who take corticosteroids (a group of medications used to treat many conditions that involve inflammation or swelling of part of the body) for a long time. Oxandrolone is in a class of medications called androgenic hormones. It works by increasing the amount of protein made by the body. This protein is used to build more muscle and increase body weight.
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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.