Antifungals: Polyenes and Antimetabolites Flashcards
what are the polyenes?
amphotericin B
nystatin
what is the antimetabolite
flucytosine
MOA amphotericin B
bind to ergosterol and increase cell permeability, create pores in cells that allow leakage of intracellualr ions and macromolecules
spectrum of amphotericin B
broad spectrum, clinically significant yeasts (candida, cryptococcus neoformans), endemic mycosis (histoplasma, blastomyces, coccidioides), ASPERGILLUS
kinetics of amphotericin B
IV only, cleared renally, highly protein bound so need large amounts or directly administered for CNS
what form of amphotericin B is safest
liposomal formulations
ADE amphotericin B
TOXIC, losing electrolytes, may have decreased LFT, creatinine levels. renal impairment occurs in nearly all patients.
MOA nystatin
bind to ergosterol and increased cell permeability, create pores to allow leakage
how is nystatin used?
only topically, so little SE.
spectrum of nystatin
most candida species
MOA flucytosine
pyrimidine analog related to 5-fluorouracil that penetrates fungal cells and is converted to fluorouracil which competes with uracil. interferes with funal RNA and protein synthesis
kinetics of flucytosine
poorly protein bound so penetrates all body compartments including CSF
spectrum of flucytosine
some candida, cryptococcus neoformans
use of flucytosine
combination with cryptococcal meningitis
ADE flucytosine
resistance seen at subtherapeutic doses, bone marrow toxicity with anemia, leukopenia, and thrombocytopenia
