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