Antifungal Drugs

Question 1

List the 2 components of fungal cell wall structure, and the important structures contained within each one.

Answer 1

Glycopeptide cell wall
-Beta glucan

Cell membrane

• Amphotericin V
• Ergosterol
• Beta glucan synthase

Question 2

List 3 classes of antifungal drugs.

Answer 2

Topical agents
Systemic agents for mild infection
Systemic agents for severe infection

Question 3

List 3 types of antifungal drugs used for severe infection.

Answer 3

Azoles
Echinocandins
Polyenes

Question 4

List 4 examples of topical antifungal agents.

Answer 4

Clotrimazole
Miconazole
Terbinafine
Nystatin

Question 5

Describe the mechanism of action of topical antifungal agents. (2)

Answer 5

1. Inhibit synthesis of ergosterol (by inhibiting the coversion of squalene into squalene epoxide)
2. Inhibit function of ergosterol (related to flexibility and fluidity of cell membrane)

Question 6

List adverse effects of topical antifungal agents.

Answer 6

Relatively non-toxic

Question 7

What type of topical antifungal agent would you give orally?

For what sort of fungal infections would you give this?

Why?

List 2 adverse effects of this treatment. (NOTE: these are very rare)

Answer 7

Oral terbinafine

For:
Skin fungi
Nail fungi

Why?
Highly lipophilic - accumulates in skin and nails after systemic administration (creates higher concentration than topical application would)

Adverse effects:
Liver toxicity
Stevens Johnson syndrome

Question 8

Give 1 example of an azole drug.

Answer 8

Fluconazole

Question 9

Which azole drugs are active against yeasts?

Which ones are active against moulds?

Answer 9

Yeasts: fluconazole

Mould: others

Question 10

Describe the mechanism of action of azoles. (2)

Answer 10

1. Inhibit ergosterol synthesis (by inhibiting conversion of lanosterol into ergosterol)
2. This damages and destroys fungal cell membranes

Question 11

What do you need to consider when prescribing azoles?

Answer 11

Many drug interactions

Question 12

List the adverse effects of azole drugs.

Answer 12

Relatively non-toxic

Question 13

Give 1 example of an echinocandin.

Answer 13

Caspofungin

Question 14

Describe the mechanism of action of echinocardins. (3)

Answer 14

1. Broad spectrum
2. Inhibit beta glucan synthesis in the cell membrane
3. This damages cell wall

Question 15

List the adverse effects of echinocandins.

Answer 15

Relatively non-toxic

Question 16

Give 1 example of a polyene.

Answer 16

Amphotericin B

Question 17

Describe the mechanism of action of polyenes. (3)

Answer 17

1. Forms membrane attack complexes which bind to the fungal membrane
2. This makes the fungal membrane permeable
3. This causes fungal cell lysis

Question 18

What do you need to consider when prescribing polyenes?

Answer 18

Very toxic - can only be given by specialists