THER.Intro to Abx I&II.9.1.15 Flashcards
What is the “Time above MIC”?
The time at which the organism is being exposed to the antibiotics at a concentration that is greater than the minimum inhibitory concentration
Analogous to the AUC/MIC
Are the following drugs bactericidal or bacteriostatic?
Protein synthesis inhibitors (except aminoglycosides)
Bacteriostatic
Name the characteristics of the patient that will play a role in the effectiveness of the drug?
Allergy
Age: eldery have more fat may serve as a resevoir for drugs
Pregnancy: greater Clerance and Vd; will drug cross placenta?
Renal/hepatic fxn: decreased fxn leads to decreased clearance
Drug interactions: augment toxicity or effectiveness
Underlying disease: burn pts are predisposed to certain infections
Define Minimum inhibitory concentration (MIC)
The lowest concentration of antibiotic that inhibits the growth of an organism.
Define: AUC/MIC
Area over the MIC = Total amount exposure of an antibiotic at a concentration > MIC
This is more easily measured as the “time above MIC”
Define Time dependent killing
- Killing depends on time of exposure above the MIC and NOT on higher serum concentrations
- Usually associated with no PAE effects; give next dose immediately after concentration is below PAE
Describe the three traits of infection that will affect treatment with abx
Severity: may affect route of administration, dose, and choice of abx. Ex: for pts in shock, IV > oral becaue the person has diminished ciruclation and drug would never get to site of infection
Site: is the abx able to reach the brain (cross BBB) for treating meningitis?
Organism: sensitivity to drugs, combination therapy, etc.
Describe pharmacodynamics
“How drug effects the body”
Represented by the: Dose response curve
Concentration (x-axis) vs effect (y-axis)
Define Concentration dependent killing
- Higher serum concentrations = More rapid and extensive killing
- We often see abx with a long PAE here—- ex: aminoglycosides, we will see killing even after concentration is below MIC.
- Prolonged PAE allows us to increase interval between doses
Define post-antibiotic effect
The amount of time it takes for bacterial growth to re-occur after the concentraion is below the MIC
gram neg: prolonged PAEs when treated with aminoglycosides and fluoroquinolones
gram positive: shorter PAE when treated with b-lactams
Bacteriostatic
- Inhibits bacterial growth
- Requires host immune defense to clear the pathogens
- Inadequate host defense may lead to continued growth and resistance after abx are discontinued
- ex: sulfonamide
Describe pharmacokinetics
What the body does to the drug: ADME
Represented by graph of: concentration of drug in body (y-axis) vs time (x-axis)
Describe the PK/PD combined curve
Tells us about the effect of the drug in the body over time
Effect: Y-axis
Time: X axis
Describe Bactericidal abx
Kills bacteria
Less dependent on host immune system (IS)
Ind for pts with inadequate or compromised IS
Required for treatment of:
»meningitis, endocarditis, osteomyelitis, febrile neutropenia
Ex: penicillin
Are the following drugs bactericidal or bacteriostatic?
Metabolic inhibitors
Bacteriostatic
