PKPD of Antimicrobial Agents Flashcards
What is antimicrobial PD?
The relationship between the antimicrobial concentration and the observed effect on the target pathogen in the body
What PK parameters can substitute Ce?
Cmas, AUC, t1/2
Why are PK parameters used for antimicrobial agents?
They are often influenced by the route and dosing regimen of the administered antimicrobial agent
What are the PD parameters used to measure antimicrobial effect?
- IC50
2, MIC - MBC
What is IC50?
The concentration of antimicrobial agent that inhibits half of the given bacterial population. IC50 is like EC50
What is MIC?
The lowest antimicrobial agents concentration that visibly inhibits bacterial growth
What is MBC?
The minimum antimicrobial agent’s concentration that kills 99.9% of bacteria
What the PD parameter most often used to describe the relationship between PK and PD of antimicrobial agents?
MIC
How are PD parameters determine in vitro?
Placing a known quantity of bacteria into multiple test tubes, and then adding increasing concentrations of a particular antibiotic, typically in log2 dilution, into consecutive tubes
What is a PK/PD index?
The quantitative relationship between PK and PD in the context of the target pathogen
What is the PK/PD index used for?
To relate PK and PD of antimicrobial agents
What is used to relate PK and PD of antimicrobial agents?
- PK parameters are divided by MIC results 2 PK/PD indices, Cmax/MIC and AUC/MIC (or AUIC)
- %T>MIC
What is %T>MIC?
The percentage of time during which the antimicrobial agents concentrations remain above its MIC
What are the PK/PD indices that categorizes antimicrobial agents?
- Concentration-dependent
- Time-dependent
- Concnetration and time dependent
What are concentration dependent agents?
Their efficacy depends on the achievement of high peal concentration (Cmax)
The higher the concentration, the greater the rate and extent of bactericidal activity
How are concentration dependent agents measured?
Cmax/MIC
The larger administered dose the higher Cmax
What are examples of concentration dependent agents?
Aminoglycoside antibiotics:
Gentamicin, Amikacin
What is time dependent agents?
The optimal bacterial kill effect depends on the percentage of time (%T) that such agents’ plasma concentration (Cp) remains/sustains to be above the MIC of the pathogen over their dosing interval.
How is time dependent agents measured?
%T > MIC
%T could be enhanced by dose fractionation while the total daily dose remains constant.
What are examples of time-dependent agents?
b-lactam antibiotics: penicillin, cephalosporins
What is concentration and time dependent agents?
that their efficacy depends on both for how long their plasma concentrations remain above the MIC value and how high their plasma concentration (Cp) gets, obviously Cmax but not exceeding from it
What is AUC 0-24?
An integrated PK parameter which accounts for time and concentration
How do you have a greater AUC value with Concentration- and time-dependent?
achieved by administering larger doses of a relatively longer plasma half-life antimicrobial agent can be administered
A longer half-life drug will persist in the plasma for an extended time compared to a drug with shorter half-life.
What are examples of concentration and time dependent?
Fluoroquinolones: Ciprofloxacin, Norfloxacin
