Antimicrobial PKPD Flashcards
Absorption
Describes oral medications that go to the GI tract or transdermal medications through the skin
Bioavailbility
% of the concentration of a non-IV medication compared to the same medication administered IV
Affected by food, gastric acidity, and chelating agents.
Distribution
Migration of the drug to various site of the body
Metabolism/Excretion
Drugs can be metabolized by the liver and then eliminated through the urine/feces. Some drugs are excreted unchanged through the urine/feces.
Antibacterials with a 1:1 IV to PO dose conversion
Azithromycin Doxycycline Levofloxacin Linezolid Metronidazole
Pharmacodynamics
Describes with drug does to the organism
Described by time-dependent activity, Concentration dependent activity and correlation with AUC
Time dependent Bactericidal Activity (%T>MIC)
Maximize the duration of the exposure
Example: β-lactams
β-lactams use extended infusion dosing strategies
Concentration dependent Bactericidal Activity (peak[cmax]/MIC)
Increase the peak concentration by giving a larger dose
Example: Aminoglycosides, Fluoroquinolones and Daptomycin
Extended Interval dosing administered higher dosages less frequently to reach initial high peak concentration, but allow the body time to clear the drug to reduce toxicity
Bactericidal dependent on the amount of drug (AUC/MIC)
Examples: Vancomycin, Tetracyclines, Oxazolidinones, Macrolides, and Fluoroquinolones
Dose fractionation studies are used to determine the index that is most predictive of bacterial killing.
Post-antibiotic Effect (PAE)
Phenomenon of delayed microorganism regrowth during in vitro testing of antimicrobials. The concentration of a particular antibiotic drops below the MIC of the organism which makes the antimicrobial agent ineffective but the regrowth of the organism remains suppressed.
β-lactams with NO renal adjustments
Ceftriaxone, Nafcillin, Oxacillin
