Antifungals

Question 1

3 forms of fungi

Answer 1

Filamentous fungi
Yeasts
dimorphic- either year or filamentous fungi

Question 2

what distinctive features do filamentous fungi have

Answer 2

hair like hyphae
mycelium which holds hyphae together
septae
produce spores

Question 3

what distinctive feature do yeasts have

Answer 3

divide by budding

Question 4

Antifungal targets

Answer 4

cell membrane- ergesterol

cell wall- B 1,3 glucan.

Question 5

Are fungi prokaryotic or eukaryotic

Answer 5

eukaryotic

Question 6

function of ergesterol

Answer 6

regulate membrane permeability.

Question 7

mechanism of egesterol synthesis.

Answer 7

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

Question 8

what part of a fungi is ergesterol part of

Answer 8

cell membrane

Question 9

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

Answer 9

cell wall.

Question 10

what are the 4 main anti fungal classes

Answer 10

Polyenes
Allyamines
Azoles
Echinocandins.

Question 11

what is the mode of action of polyenes

Answer 11

– Association with ergosterol- binds to it.

– Formation of pore-like molecular aggregates

Question 12

Main examples of polyenes

Answer 12

Amphotericin B
lipid associated Amphotericin B
Nystatin

Question 13

side effects of Amphotericin B

Answer 13

Nephrotoxicity

allergic reactions

Question 14

Why is lipid amphotercin better than normal amphotericin b

Answer 14

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

Question 15

How is nystatin prescribed

Answer 15

parenterally.

Question 16

How is amphotericin b prescribed

Answer 16

parenterally.

Question 17

What is the mode of action of allyamines

Answer 17

inhibit egosterol synthesis

acts on squalene epoxidase.

Question 18

Example of allyamines

Answer 18

Terbinafine

Question 19

Is amphotericin broad or narrow spectrum

Answer 19

broad

Question 20

Are allyamines broad or narrow spectrum

Answer 20

broad

Question 21

What are the side effects of allylamines

Answer 21

liver toxicity.

Question 22

clinical use of allyamines

Answer 22

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

Question 23

What conditions are allyamines used for

Answer 23

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

Question 24

what are the 2 types of azoles.

Answer 24

Imidazole- toxic

Triazole- non toxic

Question 25

how many nitrogen atoms sides imidazole have

Answer 25

2

Question 26

how many nitrogen atoms do triazoles have

Answer 26

3

Question 27

What is the mode of action of azoles

Answer 27

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

Question 28

Are azoles broad or narrow spectrum

Answer 28

depends on drug but mainly broad

Question 29

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

Answer 29

Fluconazole.

Question 30

Most commonly used imidazole

Answer 30

Clotrimazole- vaginal thrush

Question 31

Most commonly used Triazoles

Answer 31

Fluconazole Itraconazole Voriconazole.

Question 32

What are the side effects of azoles

Answer 32

hepatotoxicity- mild liver enzyme abnormalities.

Question 33

what drugs do azoles commonly interact with

Answer 33

Inhibit cytochrome P450 enzymes.

Question 34

what are type of infections are imidozoles used for

Answer 34

superficial infections

Question 35

What type of infections are triazoles used for

Answer 35

severe fungal infections

Question 36

What is the mode of action of Echinocandins

Answer 36

Inhibition of β-1,3-glucan synthase

Question 37

Most commonly used Echinocandins

Answer 37

Anidulafungin

Question 38

Are echinocandins broad or narrow spectrum

Answer 38

broad- although it misses out cryptococcus.

Question 39

What are the side effects of enchinocandins

Answer 39

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

Question 40

Clincial use of enchicandins

Answer 40

Systemic infections

Question 41

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

Answer 41

Synthetic analogue of cytosine

Question 42

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

Answer 42

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

Question 43

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

Answer 43

Yeasts only

Question 44

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

Answer 44

Bone marrow suppression

Question 45

Clinical use of 5-fluorocytosine (5-FC)

Answer 45

Limited | Cryptococcal meningitis

Question 46

What are the reasons for therapeutic drug monitoring

Answer 46

to minimize efficacy | to minimize toxicity

Question 47

what 3 drugs are therapeutically monitored

Answer 47

Itraconazole 5-fluorocytosine Voriconazole.