To increase efficacy of FQ, you need to increase both the AUC and the peak …

dosage AUC * PK/PD Peak * PK/PD qD mg*h/L AUC Bkpt** mg /L Peak Bkpt***

250 28 1 2.5 0.25

500 56 2 5 0.5

1000 112 4 10 1

* based on normal half-lifes; CL ~ 100 mg/dl; doses for an adult of 65 kg

** for a 24h AUC / MIC = 25 (Nightignale, Craig …)

*** for a peak / MIC = 10 (Drusano, …)

MIC

S. pneumoniae

~ 1-2 mg/L

levofloxacin (qD)