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Pharm Exam 2 > Antifungal 1 > Flashcards

Antifungal 1 Flashcards

1
Q

Yeasts shape

A

oval or round

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2
Q

Yeasts grow via

A

budding

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3
Q

Molds composed of

A

hyphae

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4
Q

Dimporphic fungi (syndromes)

A
  1. Sporotrichosis
  2. Coccidiodiomycosis
  3. Paracoccidioidomycosis
  4. Blastomycosis
  5. Chromoblastomycosis
  6. Histoplasmosis
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5
Q

Cells of fungi that are pathogenic in humans are…

A

nonmotile and have a rigid cell wall

(usually containing chitin and polysaccharides)

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6
Q

Two exceptions to the “non-transmissible” rule

A

Ringworm of scalp

Neonatal candida

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7
Q

Dermatomycoses live on ___ tissue

A

keratinized

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8
Q

Antifungals to treat dermatomycoses

A

Tolnaftate

Clotrimazole

Griseofulvin

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9
Q

Tolnaftate MOA

A

Inhibits squalene epoxidase

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10
Q

Why doesn’t inhibition of squalene epoxidase affect mammillian cells as much as fungi?

A

The fungal enzye is more sensitive to the drug

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11
Q

Steps in ergosterol synthesis

A
  • Squalene

(squalene epoxidase)

  • Protonated squalene
  • Lanosterol
  • Ergosterol
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12
Q

Other squalene epoxidase inhibitors

A

Terbenafine

Naftifine

Butenafine

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13
Q

Clotrimazole MOA

A

Inhibits +++Fe-CYP450

which catalyzes the 14a-demethylation of lanosterol

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14
Q

Normal intermediate between Lanosterol and Ergosterol contains______

A

COOH group on D ring

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15
Q

How do azoles (like clotrimazole) block CYP450 during ergosterol synthesis

A

The electrons on N bind to the Fe3+ on CYP450.

This happens more readily with fungal enzyme than with humans

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16
Q

Two other examples of -azole antifungal agents

A

Miconazole

Ketoconazole

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17
Q

___ used for systemic treatment of dermatomycoses

A

Griseofulvin

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18
Q

Griseofulvin MOA

A

Disrupts the mitotic spindle by binding to polymerized MTs to inhibit mitosis

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19
Q

Griseofulvin is used for this (possibly long term)

A

Onychomycoses

Treatment lasts up to a year since keratin in old tissue may support fungal growth.

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20
Q

Antifungals to treat systemic infections

A

Amphoteracin B

Flucytosine

Itraonazole

Fluconazole

Echinocandins

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21
Q

AMP B contains __ and ___

A

lipophilic polyene region and hydrophilic polyalcohol region

22
Q

AMP B must be administered ____ . Why?

A

IV

Poor water solubility

23
Q

Major Amp B acute reaction

A

Fever and Chills

24
Q

Major Amp limiting toxicities

A

Nephrotoxicity

hypokalemia

25
Q

AmpB is ___ for treatment of ____

A

broad spec

deep mycoses

26
Q

AmpB MOA

A

binds directly to ergosterol in fungal membranes

Opens pores that let out small organic molecules

27
Q

AmpB - binding ergosterol vs cholesterol

A

10x more strongly

28
Q

Fluorocytosine MOA

A

Susceptible fungi convert:

5FC >> 5FU >> 5 fluorodeoxyuridine monophosphate

29
Q

5FDUMP function

A

inhibits thymidylate synthase

(inhibits DNA synth)

30
Q

Mechanism of DUMP to DTMP conversion

A
  • Michael addition >> enolate created
  • added to iminium in methyleneTHF (thiss eliminates THF)
  • Uracil derivative formed
  • Delivery of hydride from THF to the uracil intermediate (via Michael reation)
  • Generates enolate >> eliminates the enzyme = product
31
Q

mechanistically, what does the 5FU do?

A

Elimination of F+ is impossible b/c Fluorine is the most electronegative element

**functions as ANTIMETABOLITE

32
Q

incorported into RNA in place of uracil

A

5-fluorouracil

Due to vanderwall radius similarity of F & H

33
Q

5FU is also used as a ___ in humans

A

Anti-cancer agent

34
Q

5 fluorocytosine is used with ___ to treat ___ infections

A

AmpB

Candida and Crypto meningitis

35
Q

High level of ____ to 5 FC

A

resistance

**administration with AmpB can kill resistant strains when they emerge

36
Q

Whats one of the mechanisms of synergy between AmpB and 5FC

A

AmpB increases permeability of fungal cells

enhanes uptake of 5FC

37
Q

5FC toxicity: main concern

A

bone marrow suppression

leads to leukopenia and thrombocytopenia

38
Q

Ketoconazole ROA and use

A

Oral

Systemic infetions (blasto, histo, coccidio, paracoc)

39
Q

Ketoconazole vs AmpB

A

Keto is tolerated better but is less effective

40
Q

Fluconazole is a ______ (as opposed to a ____)

A

Triazole (3N’s in a 5 membered ring)

Imidizole (2N’s)

41
Q

Fluconazole penetrates well into _____

A

the CNS

makes it appropriate for fungal meningitis

42
Q

Fluconazole is first line for…

A

prevention of relapse of crypto meningitis in AIDS patients (who recieved AmpB)

43
Q

Fluconazole infrequently causes…

A

hepatotoxicity

44
Q

Itraconazole composition

A

1-1-1-1 racemic mixture of 4 diastereomers

(its a triazole like fluconazole)

45
Q

Itraconazole ineffective for ___

A

treating CNS infections - doesnt appear in CSF

**very heavily bound to plasma proteins and is bound in tissues

46
Q

Itraconazole preferred over ketoconazole for ____

A

non-meningeal histoplasmosis

(also disseminated histo in AIDS patients who were given AmpB)

47
Q

Itraconazole AE’s

A

heart failure

hepatoxicity

DDI with other P450 drugs (contraindicated with Cisapride, pimozide, quinidine, and dofetilide)

48
Q

Echinocandins MOA

A

inhibit 1,3-ß-glucan synthase

Halts production of 1,3 B glucan for cell wall

49
Q

Echinocandins spectrum

Synergistic with what others?

A

Broad spec

Voriconazole

AmpB

50
Q

Echinocandins ROA and AE’s

A

IV

hepatotoxicity and hypersensitivity reactions

Pharm Exam 2 (12 decks)

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