Published online by Cambridge University Press: 15 December 2009
Pharmacodynamics is limited with respect to its ability to provide precise predictions to guide therapy because of complications related to the bound versus unbound state of the agent, tissue versus plasma concentrations, drug degradation over time, variations among microorganisms, and factors associated with the specific environment at the infection site. Antimicrobial susceptibility testing is likewise imprecise when applied to an individual animal; however, it is valuable on an animal population basis.