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Flashcards in Anti-fungals Deck (38)
1

difference btwn yeast, mold, and dimorphic fungi in terms of cellularity?

Yeast = Unicellular
Mold = Multicellular
Dimorphic = Yeast at BT, Mold at RT

2

examples of Dimorphic fungi?

Histoplasma, Blastomyces, Coccidioides (indigenous to specific areas and pt populations - ex: HIV)

3

How can you tell on a plate if it is growing yeast or mold?

yeast: Pasty colonies (resembles bacteria)
mold: Surface texture: Cottony/ woolly/ velvety/ granular…

4

Are cell membranes present in mammals? fungi?

cell wall: present only in fungicell membrane: present in both, but comprised of different compositions

5

What is the basic composition and function of the mammalian cell wall? is it antigenic or non-antigenic?

polysaccharide, proteins, and glycoproteins
fxn: shape, rigidity, strength and protection from osmotic shock

6

What is the basic composition and function of the cell membrane?

phospholipids, sterols
fxn: Protects cytoplasm, regulates intake/secretion of solutes, facilitates capsule and cell wall synthesis

7

How does the cell membrane composition differ btwn fungi and mammals?

fungi– contains ergosterol
mammals – contains cholesterol

8

knowing the compositional differences btwn the cell wall and cell membrane, what drugs can you use to target each one?

cell wall: Enchinocandins – glycan synthesis inhibitorcell membrane: Azoles or polyenes to inhibit cell membrane synthesis

9

* Terbinafine

MoA? Indications? Side effect?

MoA: blocks squalene epoxidase to prevent lansterol synthesis (for cell membrane)

Indication: Onychomycosis

ADR: GI upset, HA, hepatotoxicity, taste disturbance

10

name some ergosterol synthesis inhibitors

fluconazole
itraconazole
voriconazole
posconazole*

11

mechanism of "azoles"?

inhibits ergosterol synthesis by inhibiting the cytochrome p450 enzyme (14-a-demethylase) that converts lanosterol -> ergosterol (for cell membrane)

12

of all the azoles that we learned, which one has the poorest GI absorption/CNS penetration?

itraconazole

13

of all the azoles that we learned, which one has the least drug interactions?

fluconazole

14

indications for fluconazole?

suppression of
- cryptococcal neoforman meningitis in AIDs**
- candida albicans infections in all **drug of choice**

15

indication for itraconazole?

histoplasma
**blastomyces coccidioides

16

indication for voriconazole?

aspergillus
**prophylaxis during neutropenia and gvhd

17

indication for posconazole?

mainly zygomycosis (mucormycosis)
**but also great activity against:
- candida albicans**
- cryptococcus**
- aspergillus**- fusarium**

18

general side effects of azoles?

- testosterone synthesis inhibitor
- liver dysfunction/hepatitis (inhibits cytochrome p450)
- increase drug conc. of drugs metabolized by cyp450

19

which azole is commonly associated with gynecomastia?

ketoconazole** and itraconazole (likely due displacement of steroid hormones from serum binding proteins, resulting in a net increasein free E)

20

which azole has a greater likelihood of hepatitis? What ADR also associated with this particular drug?

voriconazole; also associated with visual disturbances

21

name 2 drugs that commonly form membrane pores in fungi. What class of drugs do they fall under?

amphotericin b (deoxycolate or lipid formulations)
nystatin

both fall under the polyene class

22

MoA for amphotericin B?

binds ergosterol (unique to fungi); forms membrane pores that allows leakage of electrolytes and proteins from the cell

“amphoTEARicin tears holes in the fungal membrane”

23

What must you administer with amphotericin B and why?

must give K supplements and Mg supplements because of electrolyte losses that occur as a result of altered renal tubule permeability

24

Why is the liposomal formulation preferred over the deoxycolate formulation of amphotericin B?

liposomal formulation decrease toxicity/adrs, but requires higher doses to achieve the same therapeutic effect

25

Indications for amphotericin B?

serious systemic mycoses
- cryptococcus
- blastomyces
- coccidiodes
- histoplasma
- candida
- mucormycosis
- fungal meningitis (intrathecal)

26

ADRs of amphotericin B? What is cool about these particular symptoms?

ampho“terrible”:
fever, chills/rigors
“shake & bake”
hypotension
nephrotoxicity** anemia (due to decr. EPO)
iv phlebitis

most of these symptoms can be prevented with prophylactic treatments (ie aspirin, diphenhydramine, hydrocortisone, slow infusion)

27

MoA for nystatin?

same mxn as amphotericin b - tears holes in the membrane

28

how is nystatin administered?

topic administration - too toxic for systemic use!

29

nystatin indications?

“swish and swallow”
oral candidiasis
diaper rash
vaginal candidiasis

30

antifungals that inhibits cell wall synthesis? What class do they fall under?

caspofungin
micafungin

all fall under the echinocandins class

31

MoA for caspofungin?

inhibit cell wall synthesis by inhibiting synthesis of ß1,3-d-glucan

32

Indications for caspofungin?

- invasive aspergillosis (3rd line rx)
- candida resistant to azoles or azole-allergic patients

33

ADR for caspofungin?

gi upset flushing (due to histamine release)fever, rash, n/vphlebitis,hepatits

34

nucleic acid synthesis inhibitors used as a anti-fungal therapy?

5-flucytosine*

35

MoA of 5-flucytosine?

inhibit DNA/RNA biosynthesis via conversion to 5-FU by cytosine deaminase

36

5-flucytosine is often used in combination with..?

amphotericin b

37

Indications of 5-flucytosine?

systemic fungal infections (cryptococcus meningitis)

38

ADR of 5-flucytosine

bone marrow suppression