Therapeutic drug monitoring: principles and key drugs
When a drug level helps, how sample timing and steady state affect interpretation, and the targets and traps for vancomycin, aminoglycosides, digoxin, lithium, phenytoin and other monitored drugs, including changes in renal function, albumin and critical illness.
Tier 2Medical 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
- A drug level is useful only if concentration predicts effect or toxicity better than dose, the therapeutic index is narrow and kinetics vary between people.
- Interpret a level against when it was taken (relative to dose and to steady state) and what was measured (total or free).
- Vancomycin: AUC24 400 to 600 mg.h/L is the Australian target (Therapeutic Guidelines 2025). Trough 10 to 15 mg/L is the fallback.
Loading the rest of the note…
Finished reading?
Sources
- Safe and effective use of vancomycinAU/NZAustralian Prescriber (Legg, Devchand, Gwee, Sandaradura and Lai, 2025;48:54-9), 2025
- Therapeutic Guidelines: AntibioticAU/NZTherapeutic Guidelines Ltd, 2025
- Therapeutic monitoring of vancomycin for serious methicillin-resistant Staphylococcus aureus infections: a revised consensus guidelineAmerican Journal of Health-System Pharmacy (Rybak et al., 2020;77:835-64), 2020
- The International Society for Bipolar Disorders (ISBD) task force report on the optimal serum lithium levelBipolar Disorders (Nolen et al., 2019;21:394-409), 2019
- Extracorporeal treatment for lithium poisoning: systematic review and recommendations from the EXTRIP WorkgroupClinical Journal of the American Society of Nephrology (Decker et al., 2015;10:875-87), 2015
- 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
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Turnstile bot check on sign-in and signed-out feedback