Time Above MIC: ?-Lactams
T>MIC (% of dosing interval) required for the static dose against most organisms in neutropenic mice vary from 25-35% for penicillins and from 30-45% for cephalosporins
The presence of neutrophils reduces the T>MIC required for efficacy by 5-10%
Free drug levels of penicillins and cephalosporins need to exceed the MIC for 35-50% of the dosing interval to produce maximum survival