LEC 21 - Antifungal Agents Flashcards Preview

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Flashcards in LEC 21 - Antifungal Agents Deck (71):
1

What is the target of the azoles?

Lanoesterol to Ergosterol synthesis 

2

What fungi is Griseofulvin used for?

Microsporum 

Trichophyton 

(Dermatophytes) 

3

What drugs are added along with Nystatin in Panalog?

Thiostrepton 

Polypeptide antibiotic 

Triamicinolone

4

What is the specific mechanism by which Terbinafine works?

Inhibits the synthesis of ergosterol 

Does so by blocking the enzyme squalene monoxygenase therefore inhibiting the conversion of squalene to sterols 

Accumulation of toxic intermediate squalene occurs 

5

How are azoles distributed throughout the body?

Tissues with high lipid content 

 

6

How is clortrimazole or Miconazole given?

Topically for treatment of yeast or dermatophyte infections 

Nasal infustion for nasal aspergillosis 

7

How is terbinafine used to treat birds?

Systemic mycotic infections 

(ie. aspergillosis) 

8

What adverse effects are seen with Amphotericin B?

Renal toxicity

9

What is posaconazole used for?

Otic + oral preperations 

10

How is Amphotericin B eliminated?

Biphasic 

65% excreted unchanged 

20% urine 

45% feces

 

11

How is Natamycin used in horses?

DOC for fungal keratitis

12

What are the two anti-fingal drugs that do not target the cell wall/membrane?

Griseofulvin

Flucytosine 

13

Polyenes (3) 

Amphotericin B 

Nystatin 

Natamyscin 

14

Why is the action of Griseofulvin so slow?

Infected cells are shed and replaced with uninfected cells

15

When is terbinafine fungistatic?

yeast infections

16

Which azole is best at reaching the cerbropinal fluid?

Fluconazole

17

Fungus susceptible to Amphotericin B - (5) 

Systemic mycoses 

Aspergillus 

Blastomyces 

Coccidioides 

Cryptococcus 

Histoplasma 

18

What fungi does Azoles work against? (4) 

Blastomyces 

Coccidioides 

Cryptococcus 

Histoplasma

19

What is the target of Griseofulvin?

Microtubules 

20

What animals is Amphotericin B used in?

Dogs 

Cats 

Horses 

21

How does renal toxicity occur due to Amphotericin B?

Causes renal vasoconstriction 

Decreased GFR 

Damage to tubular epithelium

22

What are the adverse side effects of flucytosine?

Mild GI upset 

Rarely - Bone marrow suppression 

23

Where does griseofulvin distribute?

Precursor cells of skin, hair shafts, and nails 

24

How is terbinafine adminstered?

Oral or Topically 

25

Azoles (6) 

Ketoconazole 

Fluconazole 

Clotrimazole 

MIconazole 

Itraconazole 

Posaconazole

26

What fungi does Terbinafine not reach the appropriate MIC?

Sporothrix

27

How is Nystatin used in poultry?

Feed-additive to prevent crop mycosis + mycotic diarrhea 

28

How are azoles absorbed?

With food that stimualtes bile flow 

29

Why is fluconazole + itraconazole more likely to be choosen for systemic mycoses infections?

longer half lives 

Greater activity 

Lower toxicity 

30

How is terbinafine used in dogs and cats?

Dermatophytic infections

31

How is terbinafine metabolized and excreted?

Metabolized in the liver (demethylated + deaminated + Dealkylated) 

Excreted into the urine 

32

Where does terbinafine distribute?

Skin and into sebum 

 

33

How is ketoconazole given?

Orally, BID 

for 3 to 6 months when used for systemic infections

34

How are the azoles metabolized?

Microsomal enzymes (CYP450) of the liver 

Excreted in the bile 

35

How does terbinafine move through the body?

99% is attached to albulmin 

36

Other anti-fungal agents that do not belong in specific groupings (3) 

Terbinafine 

Griseofulvin 

Flucytosine

37

How can you increase the absorption of griseofulvin?

High fat foods

38

What are the three groups of anti-fungal drugs?

Polyenes 

Azoles 

Others....

39

How is flucytosine given?

Orally 

3 to 4 times a day 

minimum of 4 weeks

40

How does terbinafine differ from azoles in regards to metabolism?

Does not block cytochrome P450 enzymes 

41

What is the specific mechanism of action for Griseofulvin?

Binds to microtubules of certain fungi and destroys the mitotic spindle structure

42

How is fluconazole and itraconazole administered?

Oral or IV to dogs + Cats for systemic mycoses 

Given for 1 to 3 months 

43

What is the half life of Amphotericin B?

24 to 48 hours 

1 to 2 weeks 

***remember it is biphasic 

44

When is terbinafine fungicidal?

Dermatophyte infectiosn

45

What is the target of terbinafine?

Squalene to Squalene epoxide synthesis 

46

What are the adverse effects of the azoles?

Vomiting, Diarrhea in cats 

47

What is the target of Echinocandins?

B-glucan synthase

48

What are the adverse effects of Nystatin + Natamycin? 

Rare 

GI upset 

49

What animals is giseofulvin used in?

Dogs 

Cats 

Horses

50

What is the topical treatment of choice for canidia + aspergillus when it comes to the azoles?

Clortimazole 

Miconazole 

Dermatophyte infections as well

51

What fungi do Nystatin + Natamycin work against?

Candida 

Malassezia 

52

How is Nystatin + Natamycin administered?

Topically to eye + ear + skin 

Orally for mucosal infections of mouth + GI tract 

53

What are the adverse effects of griseofulvin?

Leukopenia + anemia in kittnes 

Teratogenic in pregnant cats 

54

What is ketoconazole used for?

Dogs + Cats + Horses + Birds 

Systemic mycoses + severe yeast infections 

55

What situation is flucytosine used alone for treatment?

Aspergillosis + Candia infections in some birds

56

What is the exact mechanism of action for polyene agents?

Interaction with sterol of fungal membrane (Ergosterol) resulting in the loss of intracellular components 

= Pore formation 

57

Where is griseofulvin stored?

Growing keratin cell producing skin + hair + horn

58

How is griseofulvin adminstered?

orally BID in dogs and cats 

orally SID for horses

59

How is griseofulvin aborbed?

25% to 70% 

60

Where is flucytosine distributed?

Well distributed, includes the CNS

61

What is flucytosine FUNGICIDAL against?

Cryptococcus 

Canidida 

Aspergillus 

62

How is Amphotericin B adminstered?

Diluted in 5% dextrose + given IV

63

How is Nystatin absorbed and excreted?

Not absorbed well 

Excreted in feces 

64

What is the specific mechanism of action for flucytosine?

Metabolic antagonism of fungal DNA + RNA 

Converted to 5-fluorouracil which interferes with fungal DNA/RNA synthesis 

65

How is flucytosine metabolized and excreted?

Unchanged 

Excreted in urine

66

What is Amphotericin B mixed with to reduce toxicity?

Ketoconazole 

Fluconazole 

Itraconazole 

67

What specific enzyme does flucytosine inhibit?

Thymidylate synthase 

68

When is flucytosine combined with amphotericin B?

Treatment of cryptococcus in dogs + cats

69

What physiological condition in cats and dogs can be treated with Ketoconazole?

Hyperadrenocorticism 

70

What is amphotericin B mixed with to get into CNS, bone, or ocular infections?

Flucytosine

71

What is the specific mechanism of action when it comes to Azoles?

Inhibits synthesis of ergosterol 

Leads to depletion of ergosterol in cell membrane + accumulation of toxic intermediates 

Increases membrane permeability + inhibition of fungal growth