Dosing regimens are designed to deliver the correct…
Dose of drug
Route of administration
Interval between doses
What factors need to be considered for antibiotics
Drug - Pharmacodynamics/Pharmacokinetics - Toxicity Organism - Susceptibility to antibiotic class - Resistant subpopulations Patient - Pre-existing disease - Sensitivity to side effects
Maximal concentration (Cmax)
The peak plasma concentration reached
Area under curve (AUC)
The total dose of drug over the MIC
Time greater than MIC (T>MIC)
The duration for which plasma concentration is greater than MIC
Post-antibiotic effect (PAE)
The “trough” period where concentration is below MIC (but may still be having pharmacological effects)
The higher the concentration of drug…
the more rapid/effective the microbicidal effect
The longer the duration of the drug…
the more rapid/effective the microbicidal effect
Why does aminoglycosides require therapeutic drug monitoring
Measure serum levels
Monitor for therapeutic effect
Monitor for side effects
- narrow therapeutic window
- aminoglycosides are ototoxic + nephrotoxic @ high conc
- clearance of aminoglycosides is renal
Why does dosing regimen need to be adjusted
Impairment of
- Renal function
- Hepatic function
- Plasma protein levels
- Organ and tissue perfusion
Impact on:
- Volume of distribution
- Clearance
- Absorption (bioavailability)
