PTCB Certified Pharmacy Technician (PTCE)MedicationsEasy
A pharmacy technician is reviewing a prescription for 'warfarin 5 mg, take 1 tablet daily'. The patient's profile indicates they recently started taking amiodarone. What potential interaction should the technician be aware of?
- AIncreased risk of photosensitivity
- BDecreased effectiveness of warfarin
- CIncreased risk of bleeding
- DIncreased risk of hyperkalemia
Show answer & explanationAnswer & explanation
Correct answer: C. Increased risk of bleeding
Amiodarone is a potent inhibitor of CYP2C9, the enzyme responsible for metabolizing warfarin. This inhibition leads to increased warfarin levels, which can significantly raise the risk of bleeding.
Why the other options are wrong
- A. Photosensitivity is a known side effect of amiodarone itself, but not a direct interaction with warfarin.
- B. Amiodarone increases, not decreases, the effectiveness of warfarin by inhibiting its metabolism.
- D. Hyperkalemia is not a primary interaction between warfarin and amiodarone.
Warfarin-Amiodarone Interaction
Amiodarone significantly increases the anticoagulant effect of warfarin by inhibiting its metabolism, leading to a heightened risk of bleeding.
- Amiodarone inhibits CYP2C9, the enzyme metabolizing warfarin.
- Increased warfarin levels lead to higher INR and bleeding risk.
- Close monitoring of INR is crucial when co-administering.
Memory trick: Warfarin's partner Amiodarone makes the blood flow more.