Antimicrobial PK/PD: time-dependent and concentration-dependent killing
MIC, free drug and the three PK/PD indices (fT>MIC, Cmax/MIC, AUC/MIC), which antibiotic classes follow each, and how they explain extended beta-lactam infusions, once-daily aminoglycosides, AUC-guided vancomycin and underdosing in sepsis, augmented renal clearance and hypoalbuminaemia.
Tier 1Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- Pharmacokinetics describes the concentration over time; pharmacodynamics links concentration to bacterial killing. Antimicrobial PK/PD joins them through the MIC.
- Three indices predict efficacy: fT>MIC (time-dependent killing), Cmax/MIC (concentration-dependent) and AUC24/MIC (exposure-dependent). Only free (unbound) drug counts.
- The index decides the dosing strategy: give beta-lactams often or by infusion; give aminoglycosides once daily at a high dose.
Loading the rest of the note…
Finished reading?
Sources
- Therapeutic Guidelines: AntibioticAU/NZTherapeutic Guidelines Limited, current online edition, checked November 2026
- Australian Medicines HandbookAU/NZAustralian Medicines Handbook Pty Ltd, 2026
- Goodman & Gilman's The Pharmacological Basis of Therapeutics (14th ed.)McGraw Hill (Brunton and Knollmann, 2023), 2023
- Therapeutic monitoring of vancomycin for serious MRSA infections: a revised consensus guideline (ASHP, IDSA, PIDS, SIDP). Am J Health Syst Pharm 2020;77:835-64Rybak et al., 2020
- Continuous vs intermittent beta-lactam antibiotic infusions in critically ill patients with sepsis (BLING III). JAMA 2024;332:629-37Dulhunty et al., 2024
- Prolonged vs intermittent infusions of beta-lactam antibiotics in adults with sepsis or septic shock: a systematic review and meta-analysis. JAMA 2024;332:638-48Abdul-Aziz et al., 2024
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Turnstile bot check on sign-in and signed-out feedback