Antifungals Flashcards

1
Q

What are the risk factors for acquiring fungal infections?

A
  • broad spectrum antibiotics
  • indwelling catheters
  • immunocompromised
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2
Q

What is the most common fungal target for drug therapy?

A

Ergosterol

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3
Q

What is the only broad spectrum antifungal used for serious systemic infections?

A

Amphotericin B

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4
Q

What is the unique mechanism for Amphotericin B and how’s administered?

A

Very Lipophilic and binds ergosterol in the membrane of the fungi causing membrane leakage and death. IV dose only.

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5
Q

What type of toxicity does Amphotericin B have and what are the effects?

A

Total Cumulative Dose Toxicity.

Symptoms - Renal Damage, can cause potassium imbalance.

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6
Q

What antifungal is used with Amphotericin B for serious Candida and Cryptococcus infections?

A

Flucytosine

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7
Q

What is the unique enzyme that Candida and Cryptococcus express that Flucytosine takes advantage of?

A

Fungal Cytosine Deaminase

Converts Flucytosine to 5-FU, which inhibits fungal DNA replication

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8
Q

How does the synergy between Flucytosine and Amphotericin B work?

A

Administering Flucytosine with Amphotericin B allows the Amphotericin B dose to be lower with same effects, thus less side effects.

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9
Q

What are common side effects of Flucytosine? What patients should you not use it with?

A

Leukopenia and Thrombocytopenia
Heptatoxicty
–Should not use with renal insufficiency or bone marrow suppression patients–

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10
Q

What is the common mechanism of Triazoles and Imidizoles?

A

Inhibits 14-alpha-sterol demethylase preventing ergosterol synthesis, which is a fungal P450.

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11
Q

What antifungal would be used to treat cryptococcus meningitis?

A

Fluconazole

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12
Q

What triazoles would be used to treat urinary candida?

A

Fluconazole (Diflucan) - penetrates CNS and urinary tract tissues.

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13
Q

What antifungal would be used to treat Blastomyces, Histoplasma, and oral Candida?

A

Itraconazole

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14
Q

What azole would be used to treat invasive Aspergillus and common strains of Candida?

A

Voriconazole

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15
Q

What are the limitations of Itraconazole and Voriconazole?

A

They cannot penetrate CNS or urinary tract.

Only Fluconazole can be used for Candida UTIs and CNS infections. Secreted in urine unchanged.

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16
Q

What are general side effects of azoles?

A

Heptatoxicity

Many drug interactions

17
Q

What azole inhibits CYP3A?

A

Itraconazole

18
Q

Which azole can cause visual disturbances and photosensitive rash?

A

Voriconazole

19
Q

What drug is used for invasive Aspergillus and difficult Candida?

A

Caspofungin

20
Q

How does Caspofungin work?

A

Noncompetitively inhibits Beta-(1,3)-D-glucan preventing cell wall synthesis

21
Q

When would you use Caspofungin?

A

Invasive Aspergillus and Candida

–or if patients on intolerant to other drugs, or reached their maximal dose. –

22
Q

What antifungal is used to treat urinary tract and mucous membrane Candida?

A

Fluconazole

23
Q

What is another antifungal that has the same mechanism as Fluconazole and can be used as suppositories?

A

Miconazole

24
Q

What antifungals are typically used as topical application for Candida?

A

Clotrimazole and Nystatin

25
What kind of Candida does Nystatin work well for?
Azole-Resistant strains of Candida
26
What antifungal is only used as ophthalmic drops?
Natamycin, mechanism similar to Amphotericin B.
27
What are common topical medications for dermatophytic infections?
Miconazole Clotrimazole Terbinafine Tolnaftate
28
What antifungal is used topically on nails to prevent fungus from growing?
Ciclopirox
29
Which antifungal causes a toxic build up of squalene in fungi?
Terbinafine
30
What can a patient take orally for a nail infection?
Terbinafine and Itraconazole (Many drug interactions)
31
What antifungal would be used for tinea capitis in children?
Griseofulvin
32
What antifungal has cross-reactivity with penicillins?
Griseofulvin, also induces cytochromes
33
How does Griseofulvin interfere with fungal growth?
Interferes with microtubule spindles