The article by William A. Craig, titled "Pharmacokinetic/Pharmacodynamic Parameters: Rationale for Antibacterial Dosing of Mice and Men," explores the interrelationship between pharmacokinetics and pharmacodynamics in determining optimal dosing regimens for antibacterial drugs. Pharmacokinetics involves the absorption, distribution, and elimination of drugs, while pharmacodynamics focuses on the relationship between serum concentration and the pharmacological and toxicological effects of drugs. The time course of antimicrobial activity is influenced by both these factors. The author highlights that different antibacterials exhibit distinct patterns of bactericidal activity, with some showing concentration-dependent killing and others minimal concentration-dependent killing. Persistent effects, such as the postantibiotic effect (PAE), postantibiotic sub-MIC effect (PAE-SME), and postantibiotic leukocyte enhancement (PALE), further complicate the understanding of antimicrobial activity over time. The article discusses the importance of specific pharmacokinetic/pharmacodynamic parameters in predicting the efficacy of antibacterial drugs in both animal models and human infections. For β-lactams, the time above the minimum inhibitory concentration (MIC) is crucial, while for aminoglycosides and fluoroquinolones, the area under the concentration-time curve (AUC) and peak/MIC ratios are more significant. The magnitude of these parameters required for efficacy is relatively consistent across different antibacterial classes and animal models. The author emphasizes the need for further research to establish the optimal dosing regimens for various antibacterials, particularly in the context of emerging resistant organisms and rare infections. The potential value of using pharmacokinetic/pharmacodynamic parameters as guides for dosing regimens is highlighted, along with the importance of reducing the cost of drug development and improving therapeutic outcomes.The article by William A. Craig, titled "Pharmacokinetic/Pharmacodynamic Parameters: Rationale for Antibacterial Dosing of Mice and Men," explores the interrelationship between pharmacokinetics and pharmacodynamics in determining optimal dosing regimens for antibacterial drugs. Pharmacokinetics involves the absorption, distribution, and elimination of drugs, while pharmacodynamics focuses on the relationship between serum concentration and the pharmacological and toxicological effects of drugs. The time course of antimicrobial activity is influenced by both these factors. The author highlights that different antibacterials exhibit distinct patterns of bactericidal activity, with some showing concentration-dependent killing and others minimal concentration-dependent killing. Persistent effects, such as the postantibiotic effect (PAE), postantibiotic sub-MIC effect (PAE-SME), and postantibiotic leukocyte enhancement (PALE), further complicate the understanding of antimicrobial activity over time. The article discusses the importance of specific pharmacokinetic/pharmacodynamic parameters in predicting the efficacy of antibacterial drugs in both animal models and human infections. For β-lactams, the time above the minimum inhibitory concentration (MIC) is crucial, while for aminoglycosides and fluoroquinolones, the area under the concentration-time curve (AUC) and peak/MIC ratios are more significant. The magnitude of these parameters required for efficacy is relatively consistent across different antibacterial classes and animal models. The author emphasizes the need for further research to establish the optimal dosing regimens for various antibacterials, particularly in the context of emerging resistant organisms and rare infections. The potential value of using pharmacokinetic/pharmacodynamic parameters as guides for dosing regimens is highlighted, along with the importance of reducing the cost of drug development and improving therapeutic outcomes.