Which PK/PD index is most commonly targeted to optimize vancomycin therapy?

Which PK/PD index is most commonly targeted to optimize vancomycin therapy?

• A. Cmax/MIC
• B. AUC/MIC
• C. Time above MIC
• D. MIC alone

Answer: (B)

Exposure over time relative to the pathogen’s MIC best predicts vancomycin success. The most informative PK/PD measure is the AUC/MIC, because it reflects the total drug exposure the bacteria experience across the dosing interval compared to how resistant the organism is. Higher AUC relative to MIC means more sustained activity and better odds of cure, up to a point where toxicity becomes a concern. Cmax/MIC focuses on a single peak concentration, which isn’t the main driver of vancomycin’s effect. Time above MIC matters more for drugs with primarily time-dependent killing and little post-antibiotic effect, whereas vancomycin’s efficacy aligns better with overall exposure. MIC alone doesn’t account for how much drug is actually delivered over time.

Exposure over time relative to the pathogen’s MIC best predicts vancomycin success. The most informative PK/PD measure is the AUC/MIC, because it reflects the total drug exposure the bacteria experience across the dosing interval compared to how resistant the organism is. Higher AUC relative to MIC means more sustained activity and better odds of cure, up to a point where toxicity becomes a concern.

Cmax/MIC focuses on a single peak concentration, which isn’t the main driver of vancomycin’s effect. Time above MIC matters more for drugs with primarily time-dependent killing and little post-antibiotic effect, whereas vancomycin’s efficacy aligns better with overall exposure. MIC alone doesn’t account for how much drug is actually delivered over time.