This is where a fixed total daily dose is administered as a single dose or fractionated into smaller doses administered using different timing intervals (see dosing and dosing regimen).

Based on dose fractionation studies, antibacterial drugs have been classified according to the correlation between the effect of the drug (CFU count after 24h exposure to drug) and the three main PK/PD indices (peak concentration [Cmax]/MIC, AUC/MIC, or time above MIC [T>MIC]. The primary goal of the study is to achieve a reduction in CFU count at the site of infection.

See also dose finding.