LEC 2 - Antifungals Flashcards

1
Q

What are the three categories of a fungal disease?

A

Superficial
Subcutaneous
Systemic

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2
Q

What is involved in a systemic fungal infection?

A

Normally start in the lungs

Then spreads to other organs

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3
Q

What is involved in a subcutaneous fungal infection?

A

Dermis
Subcutaneous tissues
Occasionally adjacent

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4
Q

What is involved in a superficial fungal infection?

A

Skin
Other keratinized structures
Mucous membranes

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5
Q

Are most antifungals -cidal or -static?

A

Fungistatic

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6
Q

What is clearance of a fungus in a host most dependent?

A

Host’s response to the presence of the fungus

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7
Q

When is clearance in a host unlikely in regards to a fungus?

A

Immunosuppressed animals

Primary/Secondary immunodeficiency disease

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8
Q

What are the three major reasons that treating a fungal infection takes so much longer than a bacterial infection?

A

Grow more slowly
Most medications are -static so immune system has to work
Fungus can cause inflammatory response making worse

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9
Q

What are the four major classes of antifungals?

A

Allylamines
Azoles
Echinocandins
Polyenes

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10
Q

Spectrum: Allyamines

A

Broad

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11
Q

Major drugs: Allyamines

A

Naftitine
– and –
Terbinafine

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12
Q

Administration route: Naftitine

A

Topical

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13
Q

Administration route: Terbinafine

A

Topical + Systemic table

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14
Q

Action: Allyamines

A

Inhibit activity of squalene epoxidase

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15
Q

What happens when the activity of squalene epoxidase is inhibited?

A

Lack of ergoseterol + Increased squalene

= Toxic effect

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16
Q

Where does terbinafine concentrate in the body?

A

Dermis
Epidermis
Adipose tissue
Nails

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17
Q

What can terbinafine be used for?

A

Dermatophytes
Aspergillus spp.
Dimorphic fungi
Yeast

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18
Q

Spectrum: Azoles

A

Fungistatic + Broad

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19
Q

Activity: Azoles

A

Inhibition of sterol 14-a demethylase

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20
Q

Groups: Azoles (not specific medications)

A

Imidazoles
— and –
Triazoles

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21
Q

What does the inhibition of sterol 14-a demethylase cause?

A

Depletion of ergosterol and increase in 14-a methylsterols

Disrupts fungal membrane + growth

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22
Q

What is important to remember when giving an azole to an animal?

A

Cytochrome P450 dependent - can cause serious drug interactions

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23
Q

What animal is the use of Azoles contraindicated in? Why?

A

Pregnant animals

due to Teratogenicity

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24
Q

Medications: Imidazoles

A

Ketoconazole
Clotrimazole
Miconazole
Econazole

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25
Q

Medications: Triazoles

A

Fluconazole
Itraconazole
Voriconazole
Posaconazole

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26
Q

Which, Imadazoles or Triazoles, has greater affinity for fungus?

A

Triazoles

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27
Q

What is the drug of choice for aspergillus?

A

Voriconazole

28
Q

Why was Voriconazole produced?

A

To overcome resistance that was occurring to fluconazole + itraconazole

29
Q

What is posaconazole good for?

A

Deep mycoses

30
Q

Spectrum: Echinocandins

A

Narrow

31
Q

Activity: Echinocandins

A

1,3 B-glucan synthesis inhibition

32
Q

What happens when 1,3 B glucan is inhibited by Echinocandins?

A

Component of cell wall is destroyed

33
Q

Forms: Echinocandins

A

Caspofungin
Micafungin
Anidulafungin

34
Q

What is caspofungin not effective against?

A

Cryptococcus neoformans
– or –
Zygomycetes

35
Q

Spectrum: Polyenes

A

Broad

36
Q

Medication: Polyenes

A

Amphotericin B

37
Q

Activity: Amphotericin B

A

Binds to sterols
W/ somewhat of an affinity to ergosterol
changes cell permeability

38
Q

Administration: Polyenes

A

IV

39
Q

What is the problem with giving Amphotericin B via IV?

A

Nephrotoxic

– binds to sterol rich cell membranes in renal tubules

40
Q

What are the 3 formulations of polyenes?

A

Lipid complex
Liposomal
Colloid suspension

41
Q

What fungus have some resistance to polyenes?

A

Canidia
– and –
Aspergillus

42
Q

What are the five other antifungal compounds?

A
Griseofulvin 
Flucyctosine 
Isodides 
Morpholines 
Nucleoside-peptides
43
Q

Use: Griseofulvin

A

Dermatophyte infections

44
Q

Action: Griseofulvin

A

Interferes with microtubule formation

Inhibits division

45
Q

What is a side effect of Griseofulvin?

A

Teratogenic effects

46
Q

Medicine: Fluorinated Pyrimidine

A

5-Flucytosine

47
Q

Action: Fluorinated Pyrimidine

A
Cell entry 
Competes with uracil in RNA synthesis 
 = RNA miscoding + Inhibition of protein synthesis 
Inhibition of thymidylate synthesis 
   = Inhibition of DNA synthesis
48
Q

Spectrum: 5 - Flucytosine

A

Narrow - mostly yeasts

49
Q

What should 5-Flucytosine be used with? Why?

A

Quick to build resistance

Use with = Amphotericin B + Fluconazole

50
Q

What are the two types of Iodides?

A

Sodium
– and –
Potassium

51
Q

What type of iodide should be used in animals?

A

Sodium

52
Q

Action: Sodium iodide

A

Interferes with cell metabolic enzymes

53
Q

Use: Sodium iodide

A

Treatment of sporotrichosis

54
Q

What three major things can happen with Iodide use?

A

Iodism
Host defense defense system impairs
Infertility

55
Q

Define: Iodism

A
Lacrimation 
Increased respiratory secretion 
Inappetence 
Tachycardia 
Cardiomyopathy in CATS
56
Q

What causes the host defense system to be impaired with sodium iodide use?

A

Decreased immunoglobulin production
– and –
Reduced phagocytosis in leukocytes

57
Q

Medicines: Morpholines

A

Amorolfine

58
Q

Action: Amorolfine

A

Inhibits ergosterol synthesis

59
Q

Administration: Amorolfine

A

Topically

60
Q

Medication: Nucleoside Peptides

A

Nikkomycin Z

61
Q

Action: Nikkomycin Z

A

Inhibits chitin synthase - no fungal wall development

62
Q

What does Nikkomycin Z help increase the effects of?

A

Flucytosine
Azoles
Echinocandins

63
Q

Medication: Substituted Pyridone

A

Ciclopirox olamine

64
Q

Action: ciclopirox olamine

A

Alters membrane transport
Damages fungal cell membrane
Interferes with metabolism

65
Q

Spectrum: Subsituted pyridone

A

Broad

66
Q

What is Subsituted pyridone fungicidal for?

A

CA
Malassezia
Dermatophytes