Pharmacodynamics of Antimicrobials

Pharmacodynamic parameters predictive of outcome for the various classes of antimicrobials:


T > MIC

T > MIC = time that the free drug concentration is above the MIC

MIC = minimum inhibitory concentration

Time-dependent antibacterial activity; dosing should aim to maximize time that the free drug concentration is above the MIC of the pathogen(s)

Penicillins
Cephalosporins
Carbapenems
Aztreonam
Erythromycin
Flucytosine


Cmax:MIC

Cmax = peak free drug concentration

MIC = minimum inhibitory concentration

Concentration-dependent antibacterial activity; dosing should aim to achieve high peak serum drug concentration relative to the MIC of the pathogen(s), e.g. extended-interval AG dosing

Aminoglycosides (AG)
Fluoroquinolones
Metronidazole (vs anaerobes)
Amphotericin B
Daptomycin
Anidulafungin
Caspofungin
Micafungin


AUC24:MIC

AUC24 = 24h area under the free drug concentration-time curve

MIC = minimum inhibitory concentration

Concentration-dependent with time dependence; dosing should aim to maximize amount of drug relative to the MIC of the pathogen(s); this can be achieved by increasing the dose and/or giving more frequently

Fluoroquinolones
Azithromycin
Clarithromycin
Clindamycin
Tetracyclines
Linezolid
Vancomycin
Tigecycline
Colistin
Fluconazole

Isavuconazole
Itraconazole
Posaconazole
Voriconazole