In vitro models, in vivo models, and pharmacokinetics: What can we learn from in vitro models?

In vitro pharmacokinetic models of infection can make an important contribu tion to the study of the pharmacodynamic properties of an antibacterial age nt. In conjunction with animal and human pharmacodynamic evaluations, they provide data to allow for the optimization of drug dosing regimens. In vitr o models can be used simply to describe the effect of a drug on a bacterial population as well as to provide data for more-analytical studies, includi ng hypothesis testing. Analytical study designs provide information on the pharmacodynamic parameter best related to the chosen outcome, as well as it s magnitude. Factors such as the characteristics of the model (method of dr ug removal, inoculum density, and growth phase), doses simulated, species a nd susceptibility range of bacteria, and methods and analytical tools used to measure antibacterial effect will have an effect on the conclusions draw n. In vitro models have an important future role in ensuring antibiotic eff icacy and in reducing the risks of resistance.