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Flashcards in Antifungals Deck (47):
1

3 forms of fungi

Filamentous fungi
Yeasts
dimorphic- either year or filamentous fungi

2

what distinctive features do filamentous fungi have

hair like hyphae
mycelium which holds hyphae together
septae
produce spores

3

what distinctive feature do yeasts have

divide by budding

4

Antifungal targets

cell membrane- ergesterol
cell wall- B 1,3 glucan.

5

Are fungi prokaryotic or eukaryotic

eukaryotic

6

function of ergesterol

regulate membrane permeability.

7

mechanism of egesterol synthesis.

Squalene is converted to lansterol which is converted to ergesterol.
• Ist conversion requires enzyme squalene epoxidase
• 2nd conversion requires enzyme Lanosterol 14a demethylase.

8

what part of a fungi is ergesterol part of

cell membrane

9

what part of a fungi is B1, 3 glucans part of

cell wall.

10

what are the 4 main anti fungal classes

Polyenes
Allyamines
Azoles
Echinocandins.

11

what is the mode of action of polyenes

– Association with ergosterol- binds to it.
– Formation of pore-like molecular aggregates

12

Main examples of polyenes

Amphotericin B
lipid associated Amphotericin B
Nystatin

13

side effects of Amphotericin B

Nephrotoxicity
allergic reactions

14

Why is lipid amphotercin better than normal amphotericin b

• Minimize delivery of AmB to kidney cells- more selective toxicity.
redeuced nephroroxicity.

15

How is nystatin prescribed

parenterally.

16

How is amphotericin b prescribed

parenterally.

17

What is the mode of action of allyamines

inhibit egosterol synthesis
acts on squalene epoxidase.

18

Example of allyamines

Terbinafine

19

Is amphotericin broad or narrow spectrum

broad

20

Are allyamines broad or narrow spectrum

broad

21

What are the side effects of allylamines

liver toxicity.

22

clinical use of allyamines

Dermatophyte infections (superficial fungal infections)-caused by fungi which like to eat keratin.

23

What conditions are allyamines used for

• Topical use
– Athletes foot , fungal groin infection, (tinea pedis), tinea corporis, tinea cruris.
• Systemic (oral) use
– Scalp ringworm, nail fungal infection (tinea capitis), onychomycosis

24

what are the 2 types of azoles.

Imidazole- toxic
Triazole- non toxic

25

how many nitrogen atoms sides imidazole have

2

26

how many nitrogen atoms do triazoles have

3

27

What is the mode of action of azoles

• Mode of action
– Inhibit ergosterol synthesis
Lanosterol 14α-demethylase

28

Are azoles broad or narrow spectrum

depends on drug but mainly broad

29

which is the only azole which does;t work against Aspergillus

Fluconazole.

30

Most commonly used imidazole

Clotrimazole- vaginal thrush

31

Most commonly used Triazoles

Fluconazole
Itraconazole
Voriconazole.

32

What are the side effects of azoles

hepatotoxicity- mild liver enzyme abnormalities.

33

what drugs do azoles commonly interact with

Inhibit cytochrome P450 enzymes.

34

what are type of infections are imidozoles used for

superficial infections

35

What type of infections are triazoles used for

severe fungal infections

36

What is the mode of action of Echinocandins

Inhibition of β-1,3-glucan synthase

37

Most commonly used Echinocandins

Anidulafungin

38

Are echinocandins broad or narrow spectrum

broad- although it misses out cryptococcus.

39

What are the side effects of enchinocandins

Minimal effects
skin rash, nausea, vomiting, headache, diarrhoea in common with any other drug

40

Clincial use of enchicandins

Systemic infections

41

what type of drug is 5-fluorocytosine (5-FC)

Synthetic analogue of cytosine

42

What is the mode of action of 5-fluorocytosine (5-FC)

Entry into cell requires fungal cytosine perm ease.
• Inhibit RNA/protein synthesis and DNA synthesis

43

What spectrum of fungi does 5-fluorocytosine (5-FC) act against.

Yeasts only

44

What are the side effects of 5-fluorocytosine (5-FC

Bone marrow suppression

45

Clinical use of 5-fluorocytosine (5-FC)

Limited
Cryptococcal meningitis

46

What are the reasons for therapeutic drug monitoring

to minimize efficacy
to minimize toxicity

47

what 3 drugs are therapeutically monitored

Itraconazole
5-fluorocytosine
Voriconazole.