PTCB Certified Pharmacy Technician (PTCE)Patient Safety and Quality AssuranceMedium
A pharmacy technician is reviewing a patient's medication profile and notes that the patient is prescribed both Warfarin (an anticoagulant) and Bactrim (sulfamethoxazole/trimethoprim, an antibiotic). What is the MOST significant concern regarding this combination?
- AIncreased risk of photosensitivity.
- BEnhanced anticoagulant effect, leading to increased bleeding risk.
- CPotential for severe constipation.
- DDecreased effectiveness of the antibiotic.
Show answer & explanationAnswer & explanation
Correct answer: B. Enhanced anticoagulant effect, leading to increased bleeding risk.
Bactrim (sulfamethoxazole/trimethoprim) is known to significantly inhibit the metabolism of Warfarin, leading to increased Warfarin levels and a heightened risk of bleeding. This is a critical drug-drug interaction.
Why the other options are wrong
- A. Photosensitivity is a known side effect of Bactrim, but not the most significant concern when combined with Warfarin.
- C. Constipation is not a primary or significant concern for this drug combination.
- D. Bactrim's effectiveness is not decreased by Warfarin; rather, Warfarin's effect is enhanced.
Warfarin-Bactrim Interaction
The co-administration of Warfarin and Bactrim (sulfamethoxazole/trimethoprim) can lead to a significant increase in Warfarin's anticoagulant effect, greatly elevating the patient's risk of severe bleeding due to metabolic inhibition.
- Bactrim inhibits Warfarin metabolism.
- Leads to higher Warfarin levels in blood.
- Increases risk of hemorrhage.
- Requires close INR monitoring and possible Warfarin dose reduction.
Memory trick: Warfarin + Bactrim = Bleeding Risk, Be Aware!