A 70-year-old man with cardiac arrhythmia is prescribed an antibiotic for a respiratory infection. Which fluoroquinolone carries the highest risk of QT interval prolongation and should be avoided in this patient?
- A Ciprofloxacin
- B Moxifloxacin ✓
- C Levofloxacin
- D Ofloxacin
Correct answer: B. Moxifloxacin
Explanation
Moxifloxacin is associated with the highest risk of QT prolongation among fluoroquinolones. Sparfloxacin also carries a high risk but is less commonly used. Ciprofloxacin and levofloxacin have a lower risk of QT prolongation. Tendon rupture and aortic dissection are class effects, but QT prolongation is most pronounced with moxifloxacin. Therefore, moxifloxacin should be avoided in patients with pre-existing arrhythmias or those on other QT-prolonging drugs.
Reference: Katzung and Trevor's Pharmacology, 14th ed.
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Written and medically reviewed by the StethoPrep medical team.