A 45-year-old with a history of prolonged QT interval is prescribed an antibiotic for Pseudomonas aeruginosa infection. Which antibiotic is contraindicated due to risk of QT prolongation and torsades de pointes?
- A Ciprofloxacin ✓
- B Ceftazidime
- C Piperacillin-tazobactam
- D Colistin
Correct answer: A. Ciprofloxacin
Explanation
Fluoroquinolones, especially ciprofloxacin and moxifloxacin, block potassium channels and prolong the QT interval, increasing torsades risk. Ceftazidime, piperacillin-tazobactam, and colistin do not significantly affect QT interval. Baseline ECG monitoring is advised when using fluoroquinolones in at-risk patients.
Reference: Katzung: Basic & Clinical Pharmacology, 14th ed.
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