A fluoroquinolone is prescribed for a urinary tract infection. Which statement about quinolone pharmacodynamics is most accurate?
- A They are concentration-dependent killers; efficacy correlates with the AUC/MIC ratio ✓
- B They are time-dependent killers; efficacy correlates with time above MIC
- C They are bacteriostatic and require intact host immunity to achieve bacteriological cure
- D Their killing is primarily mediated by inhibition of cell-wall synthesis via DNA gyrase
Correct answer: A. They are concentration-dependent killers; efficacy correlates with the AUC/MIC ratio
Explanation
Fluoroquinolones are concentration-dependent bactericidal agents; the pharmacodynamic index best predicting efficacy is the 24-hour AUC/MIC ratio (or Cmax/MIC). Higher peak concentrations relative to the MIC produce faster and more complete bacterial killing and also suppress emergence of resistance. This is in contrast to beta-lactams, which are time-dependent and require prolonged exposure above the MIC.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.