51 Pharm Antivirals + Antifungals

Question 1

What is the difference between fungistatic and fungicidal?

Answer 1

Fungistatic - inhibits growth
Fungicidal - kills

Question 2

What is an important principle regarding duration of fungal treatment?

Answer 2

Treatment must be of sufficient duration because many drugs are fungistatic and fungi grow slowly

Question 3

Why does antifungal treatment often cause signs to worsten before they get better?

Answer 3

Inflammation

Question 4

What part of fungi do antifungals usually target?

Answer 4

Cell membrane or cell wall

Question 5

What kind of case would you prescribe Amphotericin B for?

Answer 5

Severe systemic fungal infections

Question 6

Amphotericin B is (fungistatic/fungicidal).

Answer 6

Fungicidal

Question 7

What is the MOA of amphotericin B?

Answer 7

Binds ergosterol, causes rapid K+ efflux (and other cations), inhibits fungal glycolysis, causes oxidative damage

Question 8

T or F: amphotericin B can be administered orally or IV.

Answer 8

F; poor oral bioavailability so IV

Question 9

What kind of toxicity should you worry about when using Amphotericin B?

Answer 9

Nephrotoxicity (dose dependent)

Question 10

(Imidazoles/triazoles) have a greater effect on mammalian cholesterol synthesis.

Answer 10

Imidazoles

Question 11

What is the MOA of azole antifungals?

Answer 11

Inhibits ergosterol synthesis causing accumulation of toxic methylated sterols in the plasma membrane; alters membrane fluidity and barrier function.

Question 12

Azole antifungals are (fungistatic/fungicidal).

Answer 12

Fungistatic

Question 13

What negative effects can azoles have on the patient?

Answer 13

Inhibition of mammalian CYP450; hepatotoxicity

Question 14

When in the day should ketoconazole be administered and why?

Answer 14

After a meal because it is only soluble in acidic environments

Question 15

What are the clinical indications for ketoconazole?

Answer 15

Superficial yeast infections, dimorphic fungi, or dermatophytosis

Question 16

What are some toxic/adverse effects of ketoconazole?

Answer 16

-Nausea, anorexia, vomiting
-Increase in hepatic enzymes not associated w/ injury
-Hepatic disease or failure
-Inhibition of mammalian CYP450
-Inhibits cortisol and testosterone synthesis

Question 17

T or F: fluconazole is effective against yeast, molds, and dimorphic fungi.

Answer 17

F; not effective againt molds

Question 18

How is ketoconazole eliminated?

Answer 18

Hepatic metabolism

Question 19

How is fluconazole eliminated?

Answer 19

Renal excretion

Question 20

What is itraconazole effective against?

Answer 20

All significant fungi including molds

Question 21

What kind of toxicity can fluconazole cause?

Answer 21

Rare hepatic toxicity

Question 22

What are potential adverse effects of itraconazole?

Answer 22

Vomiting (esp cats), hepatotoxicity, cutaneous vasculitis

Question 23

What is voriconazole effective against?

Answer 23

Molds

Question 24

What drug is analagous to itraconazole?

Answer 24

Posaconazole

Question 25

T or F: flucytosine is toxic to cats.

Answer 25

F; toxic to dogs

Question 26

What is flucytosine effective against?

Answer 26

Candida and cryptococcus

Question 27

What adverse effects can flucytosine have?

Answer 27

Bone marrow suppression, nausea, vomiting, diarrhea, cutaneous eruptions in dogs

Question 28

What is griseofulvin used to treat?

Answer 28

Dermatophytosis

Question 29

What is the MOA of griseofulvin?

Answer 29

Binds microtubules of mitotic spindle to inhibit fungal mitosis

Question 30

What are some toxic effects of griseofulvin?

Answer 30

Idiosyncratic toxicity in cats; teratogenic during early gestation in mares

Question 31

What are common topical antifungals?

Answer 31

Clotrimazole (otomax), enilconazole, miconazole

Question 32

What would you use caspofungin for?

Answer 32

Treat systemic aspergillosis or candidiasis

Question 33

What is the MOA of caspofungin?

Answer 33

Inhibition of glucan synthesis; disruption of cell wall

Question 34

Why is it difficult to make selective antiviral agents?

Answer 34

Viruses are obligate intracellular parasites that use host cell machinery, have variable life cycles, and can become resistant. Plus screening is tested in vitro and not all viruses will grow in vitro

Question 35

What are acyclovir and valacyclovir used to treat?

Answer 35

Herpesvirus

Question 36

What is the MOA of acyclovir and valacyclovir?

Answer 36

Targets replication by inhibiting DNA polymerase

Question 37

What domestic species is valacyclovir toxic to?

Answer 37

Cats

Question 38

What is the MOA of penciclovir and famciclovir?

Answer 38

Inhibits DNA polymerase and is a substitute for guanosine

Question 39

What are idoxuridine/trifluridine used to treat?

Answer 39

FHV-1

Question 40

What is the MOA of idoxuridine/trifluridine?

Answer 40

Interrupts DNA polymerase; substitute for thymidine

Question 41

How is idoxurine administered and why?

Answer 41

Topical and ophthalmic because it can cause toxic neoplastic changes, genetic mutations, or infertility