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D&D Infectious Disease FINAL > Pharm - Antifungals part 1 > Flashcards

Pharm - Antifungals part 1 Flashcards

1
Q

3 types of fungi

A

yeast
molds
dimorphic

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2
Q

_____ is a major problem for diabetic patients

A

onychomycoses (fungal infection of the nails)

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3
Q

fungal infections are medically called….

A

Mycoses

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4
Q

5 general categories of fungal infections

A

superficial
mucus membrane
subcutaneous
systemic (inhalation, wound)
opportunistic

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5
Q

5 patients at high risk for fungal infections

A

HIV
burn patients
barrier compromise
transplant patients
blood malignancies

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6
Q

tinea corporis

A

ringworm

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7
Q

tinea pedis

A

athlete’s foot

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8
Q

tinea barbae

A

fungal infection of beard/hair

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9
Q

tinea unguium

A

fungal infection of nails

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10
Q

tinea cruis

A

jock itch

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11
Q

tinea capis

A

fungal infection of the scalp

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12
Q

name 3 imidazoles that are antifungals

A

clotrimazole
ketoconazole
terconazole

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13
Q

2 polyene antifungals

A

amphotericin B
nystatin

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14
Q

3 echinocandin antifungals

A

capsofungin
micafungin
anidulafungin

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15
Q

MOA griseofulvin

A

interferes with microtubule assembly to inhibit mitosis

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16
Q

5 antifungals that inhibit ergosterol (steroid) synthesis

A

fluconazole
itraconazole
voriconazole

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17
Q

caspofungin is a ______ inhibitor

A

cell wall synthesis

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18
Q

name an antifungal that interferes with nucleic acid synthesis

A

5-fluorocytosine

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19
Q

site of action of oxaboroles

A

aminoacyl tRNA synthase

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20
Q

3 enzymes in ergosterol (steroid) synthesis

A

squalene synthase
squalene epoxidase
14a-sterol demethylase

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21
Q

why is ergosterol synthesis a target of many antifungals?

A

bc ergosterol is a major membrane component of fungus (NOT mammalian cells - so good target)

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22
Q

name 4 systemic antifungals for systemic infections

A

amphotericin B
flucytosine
triazoles
echinocandins

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23
Q

briefly explain the structure of amphotericin B

A

amphipathic

one side is lipid soluble and has no charge

the other side has a sugar with lot of OH groups - charged and water soluble

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24
Q

what route of administration is amphotericin B and why

A

all IV EXCEPT for fungal infections in the GI tract

poor oral absorption - insoluble in water. but if infection is in the GI, doesnt need to be absorbed anyway

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25
Q

is amphotericin B highly protein bound? what can you conclude from this?

A

more than 90% protein bound

thus, has long half life of 15 days

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26
Q

can amphotericin B enter the CNS well

A

NO

it’s big and has charge on one side

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27
Q

EXPLAIN the mechanism of action of amphotericin B

A

interacts directly with ergosterol IRREVERSIBLY– it’s ampipathic

the interaction creates a PORE in the membrane of the fungus which leads to ion leakage and ultimately death of the fungus

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28
Q

true or false

amphotericin B is considered fungicidal

A

TRUE

creates pore in the membrane by irreversibly binding ergosterol

29
Q

true or false

amphotericin B binds reversibly to ergosterol

A

FALSE

irreversibly

30
Q

resistance mechanism against amphotericin B

A

ergosterol modification or decrease in concentraiton of ergosterol in the membrane

31
Q

liposomal vs non liposomal amphotericin B

A

they are different formulations of amphotericin B but…

liposomal is less potent (so more expensive), but also less nephrotoxic toxic

32
Q

major toxicity of amphotericin B

A

nephrotoxicity

33
Q

rank the binding affinity of amphotericin B to:

liposomal vehicle
ergosterol
cholesterol

A

highest affinity to: ergosterol
liposomal vehicle
lowest affinity to cholesterol

this is good bc cholesterol is the HUMAN major membrane component - we dont want to target this

34
Q

true or false

amphotericin B is a narrow spectrum antifungal

A

FALSE

broad spectrum

really only used for life threatening systemic infections like meningitis, that is not responding to other treatment

35
Q

bc of toxicity, amphotericin B can be used initially to ___ and then be replaced with___

A

decrease fungal titers and then be replaced by other agents like azoles

36
Q

2 toxicities of amphotericin B

A

NEPHROTOXICITY
hemolytic anemia

37
Q

briefly explain the structure of flucytosine and what this means regarding its use

A

it is small and water soluble

thus, can be given orally, and also has good bioavailability on ALL body fluids including the CSF

38
Q

true or false

unlike amphotericin B, flucytosine has a narrow spectrum of action

(what does this mean about its clinical use?)

A

TRUE

thus given in combo with other agents for synergy and to avoid resistance.

many enzymes involved in the conversion of flucytosine to its active form – easy to develop resistance

39
Q

flucytosine + Amp B is used to treat……

flucytosine + itraconazole is used to treat….

A

cryptococcal meningitis

chromoblastomycosis

40
Q

explain the MOA of flucytosine

A

through cytosine permease, it is able to get into the fungus

there, it’s amine is removed by CYTOSINE DEAMINASE** and through several other steps is converted to its active form – 5-FdUmp WHICH INHIBITS thymidylate synthease – enzyme responsible for convering dUMP to dTMP and thus ultimately inhibits DNA SYNTHESIS

41
Q

active form of flucytosine

A

5-FdUmp

INHIBITS THYMIDYLATE SYNTHASE

which is responsible for converting dUMP to dTMP — thus inhibits DNA synthesis

42
Q

how does flucytosine not get into human cells to inhibit the synthesis of OUR DNA?

A

bc we have less cytosine permease and cytosine deaminase

43
Q

true or false

compared to triazole, flucytosine has a much more narrow spectrum of activity

A

true

44
Q

true or false

flucytosine is not effective against candida

A

false - it is

45
Q

fungi can increase the synthesis of ______ to compete with flucytosine

A

pyrimidines

46
Q

adverse effects flucytosine

A

bone marrow toxicity - myelosuppression, anemia, leukopenia, thrombocytopenia

47
Q

2 classes of azole antifungals

A

imidazoles and triazoles

48
Q

3 imidazoles (the rest of the azoles are triazoles)

A

3 imidazoles:

ketoconazole
miconazole
clotrimazole

49
Q

explain the MOA of azole antifungals

A

interfere with ergosterol biosynthesis

they do this by inhibiting 14a sterol demethylase**

this creates a “fake” ergosterol called toxic 14a-methyl sterols - they get incorporated into the fungal membrane. they are toxic – they cause leakage and ultimate death of the fungus

50
Q

which azoles are MORE SELECTIVE for fungal enzymes rather than human:

triazole or imidazole

A

triazoles are more selective for fungal

51
Q

what enzyme do azoles inhibit

A

14a sterol demethylase

52
Q

3 resistance mechanisms to azoles

A

-ERG11 mutation (codes for 14-a-sterol demethylase) or increased production of the enzyme

-mutation c5,6 sterol reductase

-increased efflux of azole

53
Q

most fungi are susceptible to azoles

WHAT ARE THE ONLY 2 RESISTANT FUNGI TO AZOLES**

A

mucomycosis

candida krusei

54
Q

true or false

a lot of fungi are resistant to azoles

A

FALSE - only 2

mucomycosis and candida krusei

55
Q

**important clinical concern of azoles

A

AZOLES ARE CYP3A4 (and other) INHIBITORS!!!!!!!! DDI CONCERN

56
Q

zidovudine/efavirenz + azoles

A

increased plasma levels of the antivirals bc azoles are CYP inhibitors and antivirals are CYP substrates

57
Q

true or false

itraconazole is a triazole

A

true

58
Q

AE of itraconazole

A

hepatotoxicity (d/c)
rash - hypersensitivity/SJS

59
Q

route administration itraconazole

A

oral or IV

abospriton increased when given w food - well absorbed in acidic pH

60
Q

what drug is a fluorinated bis-triazole

A

fluconazole

61
Q

advantage of fluconazole over other azoles

A

drug interactions are less common

62
Q

can fluconazole penetrate into the brain

A

yes

63
Q

what is the TI of fluconazole

A

WIDE

64
Q

fluconazole can be used to treat ______ after 2 weeks of amphotericin B

A

cryptococcal meningitis

65
Q

AE fluconazole

A

NVD
headache
rash - rare SJS
rare hepatic failure

66
Q

AE voriconazole

what kind of azole is it

how administered

A

visual disturbances, rash

triazole

oral or IV

67
Q

which particular azole is known for prolonging QTc interval

A

posaconazole

68
Q

which triazole has NO QT PROLONGATION

A

isavuconazole

69
Q
A

D&D Infectious Disease FINAL (21 decks)

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