Antifungal Agents Flashcards
Fungi
Eukaryotes
Rigid cell wall (lipid bilayer with erogosterol)
Antifungal targets
Cell wall
Cytoplasmic membrane
Nucleic acid synthesis
Nuclear division
Griseofulvin (heterocyclic benzofurans) MOA
Entry by energy-dependent transport system
Interacts with polymerized microtubules (disrupts mitotic spindles) → arrests fungal mitosis
Griseofulvin uses
Dermatophytes (ring worm)
Griseofulvin PK
Fatty food ↑ absorption
Concentrate in keratin precursor cells
Metabolized in liver
Adverse effects of Griseofulvin
Cats: leukopenia, anemia, ↑ hepatic enzyme activity and neurotoxicosis
GI disturbance, teratogenic and carcinogenic effects (high doses)
Polyenes (Amphotericin B)
Produced by Streptomyces
Most effective antifungals
Use limited by host toxicity
Polyenes (Amphotericin B) MOA
Bind to ergosterol of fungal cell mem. → leakage of cellular components → K+ efflux and hydrogen influx (fungal inhibition)
Immuomodulator
Amphotericin B uses
Aspergillosis, candidiasis, coccidiodal meningitis, pythiosis
Histoplasmosis, blastomycosis, cryptococcosis, coccidioidomysis
Amphotericin B formational
Not soluble in water
Parenteral IV prep: Lipid complexes will ↓ nephrotoxicity
Ointment or local injection
Amphotericin B PK
No oral bioavailability
Binds to cholesteral
Amphotericin B drug interactions
Synergestic action with Rifampin and 5-flucytosine
Amphotericin B drug interaction toxicity
Aminoglucoside + cyclosporin: nephrotoxicity
Digitalis: Cardiotox
Curariform: NM block
Mineralocorticoids: Hypokalemia
Thiazide diuretics: Hypokalemia and hyponatremia
Antineoplastic: cytotoxic
Amphotericin: neophrotoxic
Side effects of Amphotericin B
First: renal vasoconstriction
Second: PU, concentration defects, nephrocalcinosis acification abnormalities, renal tubular acidosis → metabolic acidosis
Precipitation of Ca in acid environment
Azole antifungals
Synthetic drugs
Safety profile more
Broad spectrum
Topical, oral and IV