Breakpoints of FQ: two problems ...
Classical breakpoints of older FQs and of levofloxacin have been probably set too high and will correspond to 24h AUC / MIC - based PK/PD breakpoints only if
- clearance is lower than in normal subjects
- accepting an 24 AUC / MIC ratio of 25 as being sufficient…
- considering total drug concentrations
Classical FQ breakpoints almost never correspond to a peak / MIC ratio ? 10 !