Drug interactions between Coumadin and phenytoin
Results for the following 2 drugs: |
|
|---|---|
| Coumadin (warfarin) | |
| phenytoin | |
Interactions between your selected drugs
warfarin ⇔ phenytoin
Applies to: Coumadin (warfarin) and phenytoin
MONITOR: Some oral anticoagulants have been reported to increase phenytoin half-life and serum concentrations, possibly by inhibiting CYP450 metabolism. The addition of phenytoin to warfarin therapy has initially increased prothrombin time, but thereafter reduced anticoagulant effects. The mechanism is not known, but may be due to initial CYP450 metabolic inhibition, followed by isoenzyme induction. Data have been conflicting.
MANAGEMENT: Phenytoin serum concentrations and INR/PT should be monitored in patients receiving this combination and whenever the dosage is changed or discontinued. Patients should be advised to promptly report any signs of bleeding (e.g., pain, swelling, headache, dizziness, weakness, prolonged bleeding from cuts, nosebleeds, bleeding of gums from brushing, red or brown urine, or red or black stools) or hydantoin toxicity (e.g., drowsiness, visual disturbances, change in mental status, seizures, nausea, or ataxia) to their physician.
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