Levofloxacin vs Moxifloxacin
## Overview
Both levofloxacin and moxifloxacin are respiratory fluoroquinolones used for CAP and other respiratory tract infections. Moxifloxacin adds anaerobic activity but cannot be used for UTI. Levofloxacin maintains urinary efficacy.
## Mechanism of Action
Both inhibit DNA gyrase and topoisomerase IV. Moxifloxacin's C8-methoxy group provides greater anaerobic activity. Both are concentration-dependent antibiotics.
## Antimicrobial Spectrum
Levofloxacin: excellent S. pneumoniae, moderate Pseudomonas, excellent atypicals, no anaerobes. Moxifloxacin: similar to levofloxacin plus excellent anaerobic coverage, better S. aureus, no Pseudomonas.
## Clinical Comparison
For CAP: both guideline-recommended as monotherapy (IDSA/ATS). For complicated intra-abdominal infections: moxifloxacin can be used as monotherapy (anaerobic coverage); levofloxacin requires addition of metronidazole. For UTI: levofloxacin only.
## QTc
Both prolong QTc; moxifloxacin more than levofloxacin.
## Key Takeaways
- Both respiratory FQs for CAP; moxifloxacin adds anaerobic coverage
- Levofloxacin: can treat UTI; moxifloxacin cannot
- Moxifloxacin: greater QTc risk
Verdict
For CAP, both are equivalent first-line options. Moxifloxacin is preferred when anaerobic coverage is needed without a second agent. Levofloxacin is preferred when UTI or Pseudomonas coverage is required. QTc risk is higher with moxifloxacin.