anti fungal drugs Flashcards

(55 cards)

1
Q

Why do ppl get fungi infections?

A

Immune system declining

Large application of antibiotic??

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2
Q

Fungal infections fall into 2 distinct categories

A

Superficial mycoses (skin, mucous )
-contagious

Deep seated mycoses (systemic, lung, CNS)
-non-contagious

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3
Q

allylamine and benzylamine antifungal drugs

A

inhibit ergosterol biosynthesis at the level of squalene epoxidase

naftifine
terbinafine
butenafine

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4
Q

azole antifungal drugs

A

inhibit cytochrom P450 dependent enzymes C14 a-demethylase involved in the biosynthesis of ergosterol

Imidazoles (less potent)
-miconazole
-clotrimazole
-ketoconazole

Triazoles(potent)
- fluconazole
-itraonazole
-voriconazole
-posaconazole

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5
Q

polyene antifungal drugs

A

interact with sterols in the cell membrane to form channels through which small molecules leak from the inside of the fungal cell to the outside and kill the fungal

nystatin
pimaricin (natamycin)
amphoteticin B

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6
Q

echinocandins

A

concentrated-dependent,

noncompetitive inhibitors of b-1,3 gluten synthase

caspofugngin
micafungin
anidula fungin

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7
Q

anti metabolit and other antifungal drugs

A

5-fluorytosine acts as an inhibitor of both DNA and RNA synthesis via the intracytoplasmic conversion of 5-flurocytosine to 5-fluorouracil

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8
Q

polyene structure

A

alternating conjugated double bonds that constitute a part of there macrolide ring structure

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9
Q

is polyenes are fungicidal or fungistatic

A

fungicidal

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10
Q

what is polyene toxicity due to ?

A

polyenes bind to cholesterol, although they have a 500x affinity for ergosterol over cholesterol

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11
Q

what was the first broad spectrum anti fungi

A

nystatin

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12
Q

what forms are nystatin available in

A

topical cream
oral suspension
pill

not available IV for humans

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13
Q

what bacteria was natamycin isolated from

A

streptomycin natalensis from South africa

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14
Q

this medication is not absorbed systemically, used for the treatment of fungal keratitis and used as a natural antifungal food additive

A

natamycin

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15
Q

amphotericin B dosage form

A

injection as well as pill

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16
Q

why is the use of amphotericin B limited

A

toxicity in the liver and kidneys

don’t give with other nephrotoxic drugs

foliation with liposomes has been approved

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17
Q

amphotericin B characteristics

A

insoluble in water
must be formulated as a suspension that is not absorbed in GI
systemic= IV administration
highly protein bound
half life >18 hrs
does not close BBB

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18
Q

toxicities of amphotericin B

A

simulate host immune cells –> release of inflammatory cytokine

nephrotoxicity
hypokalemia
hypomagnesemia
bone marrow suppression

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19
Q

what was the first antifungal allyamine

A

naftifine

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20
Q

what drug was synthesized as a potential serotonin reuptake inhibitor

A

naftifine

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21
Q

naftifine is only used for

A

topical indications

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22
Q

terbinafine (lamisil) characteristics

A

readily absorbed in the GI
40% ora biovailability
high level of metabolism by multiple CYP
high protein binding
plasma half-life of 36 hrs
accumulates in nails with a half life of 300hrs

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23
Q

Terbinafine is active against

A

a broad spectrum of fungal strains

24
Q

this is a benzylamine instead of a allylamine

25
tolnaftate
-thiocarbamate that can be made very expensive -athletes foot, ringworm, jock itch -only topical -no candida
26
amorolfine
-onychomycosis treatment -ony used topically -can be combined with terbinafine to improve efficacy
27
Azole
-five membered nitrogen heterocyclic ring -containing at least one other non carbon atom ( n, s, o)
28
what are imidazole agents usually used for
external fungal infections
29
what are triazole agents more commonly used for
systemic infections
30
clotrimazole
-first discovered -a stable carbocation, imidazole ring -not well absorbed -cream, aerosolized spray, solution (ear inf)
31
Miconazole
-2nd member of azoles -imidazole ring -most widely used -superficial and internal use -neonatal thrush -absorbed when taken internally --> DDI -racemic compound , only R - active enantiomer not used due to cost
32
what azoles are substituted with a chlorine
isoconazole econazole
33
what azoles are substituted with a sulfur
feniconazole ( more rapid clearance) sulconazole tioconazole (in the rink instead of linker) sertaconazole ( cyclic sulfur atom) butoconazole ( linker atom on other ring)
34
omoconazole
- has designed simple pH sensitivity onto limited half-life of the active ingredient -external use only -accidental ingestive is safe bc will not survive stomach acid
35
oxiconazole
acid sensitive functional group the helps render the compound safer for accidental ingestion
36
Bifonazole
-structually unique azole -target two different processes in the sterol biosynthesis pathway -reason why azoles should be limited by ppl who are taking statin to control cholesterol
37
ketoconazole
- first azole to be used for systemic candida -poor PK ( moderate absorption, high protein binding, short half life)
38
Itraconazole
-better pharmacokinetic than ketoconazole -readily metabolized by CYP3A4 -99.8% protein bound, protects it from rapid metabolism and clearance
39
posconazole
- the most active triazole for systemic infections -excellent PK profile -no significant adverse event up to 1600 mg/day
40
fluconazole
- two triazole units -does not have a chiral center -less expensive -less likely ti have undesired side effect by a spector isomer -broad spectrum -excellent PK (90% bioavailability ) - not highly metabolized -inhibit 2c9, 3A4
41
terconazole
a simplified and cheaper triazole
42
voriconazole
-available as tablet and IV -DOC for aspergillosis - ADR: hepatotoxicity, visual disturbances, hallucinations, rash, QT prolongation - many DDI (immunosuppressants)
43
abafungin
- not an azole -ihibits 14a-sterol demethylase -limited antibacterial activity -suggesting more than one MOA
44
what is the penicillins of antifunal
echinocandins
45
echinocandins and pneumocandin moa
herbal compounds able to block cell wall synthesis
46
capsofungin
used to treat aspergillosis
47
are echinocandins fungicidal or static
fungicidal agents candida spp fungistatic against aspergillus
48
echinocandins AE
hepatitis rash
49
caspofungin
-the first to be approved by FDA 27 years after echinocandins -broad spectrum antifungal activity -new class -IV only -half life = 10 hrs , 1 single injectable is suitable -used for patients that don't respond to other
50
micafungin
-injectable -similar PK to caspofungin -no DDI -decreased toxicity -useful for the Treatment of severely immunocompromised patients
51
anidulafungin
-newest antifugual -longer half life = 27 hours -lower protein bouncing =84% -metabolism through hydrolysis** -no CYP** -no DDI -excellent therapeutic index
52
all of the echinocandins represent the
last line defense
53
griseofulvin
-ringworm -oral suspension (insoluble) -poor oral biovailabity -half life 9 hours * -metabolized by bioconjugation **
54
flucytosine
-a nucleic acid analog -water soluble -well absorbed after oral Administration -used with other antifungal -flucytosine+ amp B to treat cryptococcosis and disseminated candidiasis -flucytosine + azoles treat cryptococcal meningitis
55
ciclopirox
-mechanism unknown -used in combination with azole or allylamine