Drug interactions between Coumadin and Tracleer
| Results for the following 2 drugs: |
|---|
| Coumadin (warfarin) |
| Tracleer (bosentan) |
Interactions between your selected drugs
warfarin ↔ bosentan
Applies to:Coumadin (warfarin) and Tracleer (bosentan)
MONITOR: Coadministration with bosentan may decrease the plasma concentrations of warfarin and other oral anticoagulants. The mechanism is bosentan induction of CYP450 2C9 and 3A4, two isoenzymes that are responsible for the metabolic clearance of warfarin. According to the product labeling, bosentan (500 mg orally twice a day for 6 days) decreased the plasma concentrations of the biologically less active R(+) enantiomer of warfarin by 38% and the more active S(-) enantiomer by 29%. In clinical studies involving patients with pulmonary arterial hypertension treated with bosentan and warfarin, clinically relevant changes in INR or warfarin dosage were not observed (baseline vs. end of studies), and the need for warfarin dosage adjustments due to changes in INR or emergence of adverse events was similar among the bosentan and placebo groups. However, there has been a case report of a 35-year-old patient stabilized on warfarin for 3 months who had a decrease in INR 10 days after starting bosentan, which subsequently required a 64% increase in her warfarin requirement. No data are available for other oral anticoagulants, although at least one other coumarin derivative is known to be metabolized by CYP450 2C9.
MANAGEMENT: Patients should be closely monitored during concomitant therapy with oral anticoagulants and bosentan. The INR should be checked frequently and anticoagulant dosage adjusted accordingly, particularly following initiation, discontinuation, or change of dosage of bosentan in patients who are stabilized on their anticoagulant regimen.
See also...
Drug Interaction Classification
The classifications below are a guideline only. The relevance of a particular drug interaction to a specific patient is difficult to determine using this tool alone given the large number of variables that may apply.
| Major | Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit. |
| Moderate | Moderately clinically significant. Usually avoid combinations; use it only under special circumstances. |
| Minor | Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan. |
Do not stop taking any medications without consulting your healthcare provider.
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