Antifungals

Question 1

Echinocandins

Answer 1

Use = candidosis
MoA = 1,3-B glucan synthase (inhibits glucan synthesis in the fungal cell wall
Examples –> anidulafungin, caspofungin, micafungin

Question 2

Polyenes

Answer 2

MoA = bind ergosterol in membrane disrupting integrity

Examples

• nystatin –> topical candida infections
• Amphotericin B –> life threatening systemic mycoses in IC (cryptococcal meningitis, mucormycosis)
  - -> delivered into ventricles for meningitis
  - -> toxicity = fever, hypotension + renal failure
  - -> can be given with flucytosine to decrease risk of SE + decrease risk of selecting for mutants resistant to flucytosine

Question 3

Azoles

Answer 3

MoA = inhibit ergosterol synthesis

• -> broad spectrum (active against some Gram +ve bacteria)
• -> imidazoles (clotrim, micon, econ, ketocon)
  - only used topically because they inhibit cytochrome P450
• -> triazoles (flucon, itracon, voricon, posacon, isavucon)
  - fluconazole can cause renal failure. C glabrata + C krusei are resistant

Question 4

Terbinafine

Answer 4

MoA = inhibits ergosterol synthesis
Use = dermatophytes + onychomycosis

Question 5

Griseofulvin

Answer 5

Use = dermatophytosis + onychomycosis
–> oral use only
MoA = prevents separation of chromosomes in mitosis via tubulin binding (affecting microtubule structure)
–> true Abx with antifungal properties

Question 6

5-flucytosine

Answer 6

Use = serious candida + Cryptococcus neoformans infections
—> pathogenic yeasts
—> good CSF penetration
—> developes resistance easily so use with AmB / azoles
MoA = pyrimidine analogue