NAPLEX Practice Exam 2025 – Comprehensive Test Preparation

Bactrim (sulfamethoxazole/trimethoprim) is known to interact with warfarin, leading to an increase in INR (International Normalized Ratio). Warfarin is a commonly used anticoagulant medication, and when taken concomitantly with Bactrim, it can potentiate the effects of warfarin, resulting in an increased risk of bleeding. Monitoring of INR levels is crucial when these medications are used together to prevent complications related to overanticoagulation. This is why the correct answer is B.

The other options are not typically associated with Bactrim:

- A. QT prolongation is a potential side effect of certain antibiotics like macrolides and quinolones, but not commonly seen with Bactrim.

- C. Infusion reactions are more common with medications given intravenously rather than orally, and Bactrim is usually administered orally.

- D. Myopathy is not a commonly reported side effect of Bactrim; however, muscle-related side effects may occur rarely in some individuals.