Pharmacokinetics/pharmacodynamics (PK/PD) approach in the veterinary medicine

Among veterinary drugs, antibacterial drugs are frequently used in the clinical practice. The aim of antibacterial therapy is to enhance clinical outcome and eliminate pathogenic microbes. Antibacterial pharmacokinetic/pharmacodynamic (PK/PD) relationship reflects a correlation between the antibacterial drug concentration in the blood, the concentration of biologically active drug at the site of the infection, and the sensitivity of the microbe. The PK parameters, such as AUC and C-max, describe the fate of the drug in the host. The PD parameters, such as MIC, describe the inhibitory effect of the drug on bacterial pathogens. The three most frequently used PK/PD indices are ratio of area under the concentration time curve at 24 h to the MIC (AUC(0-24)/MIC), the ratio of the peak drug concentration to the MIC (C-max/MIC), and the percentage of the dosing interval for which the plasma concentration exceeds the MIC (%T > MIC). Using of PK/PD approach in veterinary medicine can optimize the right dosing regimen. Therefore, reduced toxicity and reduction in the incidence of resistance are important consequences. The emergence of resistance is a global issue in human and veterinary medicine alike. The aim of this review is to introduce PK/PD relationships in veterinary medicine based on in vitro and in vivo models.