Did a drug interaction complicate this injury?

July 11, 2018

Figure 1 Quiz of the Week

A 76-year-old male presents with a progressive headache, dizziness, and confusion after falling from his bed the night before. He currently takes warfarin following a mechanical valve replacement 11 years ago, and has been recently diagnosed with depression. A CT scan reveals a subdural hematoma and the patient’s INR measures 7.5. 

Which of the following is most likely to increase the anticoagulant effect of warfarin?

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Image credit: @JRADS.


Answer: Fluoxetine

Selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine may inhibit the metabolism of warfarin and increase its anticoagulant effect. It is suggested that patients on antidepressants have their INR closely monitored.

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