Pharmacological indices in antibiotic therapy.

After 60 years of antibiotic treatment, attempts to rationalize it have culminated in the use of pharmacological indices. These indices facilitate comparison of the activity of different antibiotics and serve as a sound basis for antibiotic dosing. Pharmacokinetic parameters (e.g. AUC, Cmax) and pharmacodynamic parameters (mostly MIC) are used for this purpose. For the so-called concentration-dependent antibiotics, the pharmacological indices AUC/MIC and Cmax/MIC are used, whereas for time-dependent antibiotics, the pharmacological index T>MIC is used. Some authors believe that the index AUC/MIC can be used as a universal index, but, not all experts accept this generalization. As the various pharmacological indices have been defined inconsistently in the literature, the International Society for Anti-Infective Pharmacology (ISAP) has published a paper on the terminology of pharmacokinetic and pharmacodynamic parameters and the pharmacological indices. This paper will help to ensure uniform use of terminology. In addition, we point out that the use of pharmacological indices should consider the differences in pharmacokinetics (patient characteristics and localization of the infection) and the differences in pharmacodynamics of antibiotics (beyond MICs) with different pathogens (e.g. Gram-positive and Gram-negative).