Antifungals

Question 1

True or False: Fungal treatment should be topical if possible

Answer 1

True, because of the adverse effects of giving it systemically

Question 2

What are the three principles of antifungal therapy?

Answer 2

• Fungal infections often occur in immunosuppressed patients or patients on prolonged antimicrobial therapy
• Long term therapy often required
• Often have severe systemic side effects, so local or topical use is preferable

Question 3

Which fungi are systemic?

Answer 3

• Histoplasma capsulatum
• Cryptococcus neoformans
• Coccidioides immiti
• Blastomyces dermatitidis
• Candida spp.
• Aspergillus spp

Question 4

What is the mechanism of action of polyene antifungals?

Answer 4

Polyene antifungals attack the cell membrane of fungal organisms (bind to egosterol in the fungal cell membrane and increase membrane permeability, causing leakage and death)

Question 5

What class of antifungal is Amphotericin B?

Answer 5

Polyene antifungal

Question 6

Is Amphotericin B a systemic or local antifungal?

Answer 6

Systemic

Question 7

Is Amphotericin B fungicidal or fungistatic?

Answer 7

Fungicidal

Question 8

What is the main adverse effect of Amphotericin B?

Answer 8

Nephrotoxicity (basically all animals that take this medication will show this)

Question 9

Amphotericin B is _________ dependent

Answer 9

Concentration

Question 10

What class of antifungal is nystatin and natamycin?

Answer 10

Polyene antifungals

Question 11

What condition is natamycin commonly used to treat?

Answer 11

Keratomycosis (fungal infection of the cornea)

Question 12

Is natamycin a systemic or local antifungal?

Answer 12

Local (topical)

Question 13

Is nystatin a systemic or local antifungal?

Answer 13

Local (topical) is not absorbed from the GI tract

Question 14

What is the mechanism of action of azoles?

Answer 14

They inhibit ergosterol synthesis

Question 15

Are azoles fungicidal or fungistatic?

Answer 15

Fungistatic

Question 16

What are the systemic azoles?

Answer 16

Triazoles

Question 17

What are the local azoles?

Answer 17

Imidazoles

Question 18

Which azole affects mammalian steroid synthesis?

Answer 18

Imidazoles

Question 19

What are the two triazoles?

Answer 19

Itraconazole and fluconazole

Question 20

What are the three imidazoles?

Answer 20

• Ketoconazole
• Clotrimazole
• Miconazole

Question 21

What is unique about ketoconazole?

Answer 21

Although it’s an imidazole, it is used systemically as well

Question 22

What are the main adverse effects of ketoconazole? What should you give it with?

Answer 22

• Inhibits sex hormone synthesis
• Inhibition of mammalian P450
• Do not use in pregnant animals
• Give with food (acid-soluble)

Question 23

What is a main contraindication of ketoconazole?

Answer 23

Patients with liver disease

Question 24

What is the first line treatment for non-life-threatening systemic mycoses that do not involve the CNS?

Answer 24

Itraconazole

Question 25

Which antifungal is commonly used to treat dermatophytes?

Answer 25

Itraconazole (accumulates in keratin)

Question 26

What is pulse therapy?

Answer 26

Pulse therapy consists of administering usual dose for 2 consecutive days per week for duration of treatment (for skin treatments only)

Question 27

What is the first line treatment for systemic mycoses with ocular or CNS involvement?

Answer 27

Fluconazole (because it crosses BBB - okay to use in renal patients, just reduce the dose)

Question 28

What is a main contraindication of fluconazole?

Answer 28

Patients with kidney disease

Question 29

What is miconazole commonly used to treat?

Answer 29

Malassezia dermatitis (topical)

Question 30

Which antifungal is commonly used to treat Malassezia dermatitis that doesn't respond to topical therapy?

Answer 30

Itraconazole

Question 31

Which antifungal is combined with steroids and antibiotics for treatment of otitis in dogs?

Answer 31

Clotrimazole

Question 32

What is the mechanism of action of allylamines?

Answer 32

They inhibit ergosterol synthesis

Question 33

Name a drug in the allylamine class

Answer 33

Terbinafine

Question 34

Is terbinafine a systemic or local antifungal?

Answer 34

Both

Question 35

Is terbinafine fungicidal or fungistatic?

Answer 35

Fungicidal

Question 36

Which antifungal is synergistic with Amphotericin B?

Answer 36

Flucytosine

Question 37

True or False: Chlorhexidine alone is effective in the treatment of dermatophytosis

Answer 37

False

Question 38

Which compound can be used to treat white line disease in horses?

Answer 38

Chlorine dioxide gas