Antimicrobial Pharmacodynamics: PK/PD Indices (T > MIC, Peak/MIC, AUC/MIC) (Clinical Treatise 2021)
Eradicating bacterial pathogens while suppressing the emergence of antimicrobial resistance demands alignment with specific class-dependent PK/PD drivers.
Pharmacological Mechanism & Kinetic Schema
Time-Dependent Killing of Beta-Lactams and Extended Infusions
Penicillins, Cephalosporins, and Carbapenems exhibit zero concentration-dependent killing once levels exceed 4 to 5 times the bacterial MIC. Clinical cure is determined strictly by the percentage of the dosing interval that unbound drug concentration exceeds MIC (%fT > MIC). Administering Meropenem or Piperacillin-Tazobactam as prolonged 3-to-4-hour infusions significantly elevates clinical survival in critically ill septic patients.
Concentration-Dependent Synergy of Aminoglycosides
For Gentamicin, Tobramycin, and Amikacin, the killing velocity and post-antibiotic suppression of regrowth depend entirely on achieving high peak-to-MIC ratios (Cmax/MIC >= 10). High-dose extended-interval dosing achieves rapid bacterial lysis while lowering trough exposure to prevent proximal tubule phospholipidosis.
Suppression of the Mutant Selection Window (MSW)
Sub-therapeutic antibiotic exposure within the Mutant Selection Window (between the MIC and the Mutant Prevention Concentration, MPC) selectively enriches resistant bacterial subpopulations. Maintaining clinical exposure targets above the MPC prevents the emergence of secondary resistance mutations.
Clinical Pharmacologist & Biochemist · Specialist in Pharmacokinetics & Hospital Pharmacotherapy · Published on June 16, 2021 at 02:28
