Antifungals Flashcards Preview

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Flashcards in Antifungals Deck (48):
1

What are the 2 forms of pathogenic fungi?

Filamentous fungi and yeast

2

What characterises yeast?

Divide by budding

3

What characterises filamentous fungi?

Elongated cells divided by cell walls. Divide by spores

4

Dimorphic fungi

Appear in yeast and filamentous form depending on environmental conditions

5

5 antifungal targets

cell wall
cell membrane
protein synthesis
DNA synthesis
Mitosis

6

What is the main component of fungal cell walls?

beta 1-3 glucan

7

What is cholesterol equivalent component in the cell membrane of fungi?

ergosterol

8

What is the function of ergosterol?

Regulation of membrane permeability

9

Describe the formation of ergosterol

Squalene>squalene epoxidase>lanosterol>lanosterol 14 alpha demethylase>ergosterol

10

beta 1-3 glucan is a large polymer of what?

UDP glucose

11

What enzyme synthesises beta 1-3 glucan?

beta 1-3 glucan synthase

12

What are the 4 classes of antifungals?

Polyenes
Allylamines
Azoles
Echinocondins

13

Give 2 examples of polyenes

Amphotericine B, Nystatin (not used anymore)

14

How do polyenes work?

Form pores in ergosterol membrane resulting in loss of membrane integrity and leakage of K+

15

Give 3 of fungi that AmB treats

Aspergillus
Candida
Crytococcus

16

Adverse effects of amphotericin B

allergic reactions
Nephrotoxicity- pores form in human cell membranes

17

How is amphotericin B administered for serios/systermic infections?

Parenterally

18

How do lipid-associated Amphotericin B antifungals work?

Combining AmB to lipids minimises its delivery to kidney cells and reduces nephrotoxicity

19

In what cases is nystatin used?

Superficial infections e.g. oral/vaginal candidiasis

20

Clear cut nodule with cavity in teh middle of it. Fungus sits in the lung and causes localised infection.

Pulmonary aspergillosis

21

Example of allyamines

Terbinafine

22

What is terbinafine used for?

Athlete's foot-tinea pedis

23

How to allyalanines work?

Inhibit ergosterol synthesis

24

Is terbinafine broad spectrum or narrow spectrum?

Broad

25

Adverse effects of terbinafine?

Liver toxicity (jaundice, hepatitis)

26

Examples of dermatophyte infections that terbinafine is used to treat

Superficial fungal infections e.g. tinea pedis
Systemic use e.g. scalp ringworm, onychomosis

27

How do azoles work?

Inhibit ergosterol synthesis (lanosterol 14 alpha demethylase inhibitors)

28

Are azoles broad or narrow spectrum antifungals?

Broad

29

What antifungal is not effective against aspergillus?

Fluconazole

30

2 types of azoles

Imidazoles
Triazoles

31

What is the difference, structurally, between imidazoles and triazoles

Imidazoles- 2 N atoms
Triazoles- 3 N atoms

32

Which is more toxic; imidazoles or triazoles?

Imidazoles

33

Example of an imidazole and what it's used for

Clotrimazole, used for candidiasis

34

3 examples of triazoles

fluconazole
itraconazole
voriconazole

35

Adverse effects of azoles

Hepatotoxicity (mild liver enzyme abnormalitis or life threatening hepatitis)
Drug interactions; inhibit cytochrome p450 enzymes so conc. of drugs that are metabolised by this enzyme increase

36

What types of fungi is fluconazole effective against

yeasts

37

What types of fungi is itraconazole/vcorconazole effective against

yeasts
aspergillus

38

What types of fungi is pasaconazole/isavuconazole effective against

yeasts
aspergillus
mucuraceous moulds

39

How do echinocondins work?

Inhibit beta 1-3 glucan synthase resulting in the construction of severely abnormal cell walls

40

Example of echinocondin

AnidulaFUNGIN

41

What types of fungi are echinocondins effective against?

Aspergillus and candida, misses certain moulds and cryptococcus

42

Are echinocondons used for systemic or superficial infections, and how are they administered?

Systemic infections, parenteral formulations only

43

An antifungal that is a synthetic analogue of cytosine

5 fluorocytosine

44

How does 5 fluorocytosine work?

Inhibits RNA/DNA synthesis of fungal cytosine permease- prevents entry of fungus into the cell

45

What is 5 fluorocytosine effective against?

Yeasts e.g. Candida and cyptococcus

46

Adverse effects of 5 fluorocytosine

bone marrow suppression

47

What is 5 flurocytosine used for clinically

Crytococcal meningitis (in combination with AmB)

48

What 3 antifungals require therapeutic drug monitoring (to minimize toxicity and maximise efficacy)

5 flurocytosine
Itraconazole
Voriconazole