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Pharmacology > Exam 3: Antifungals > Flashcards

Exam 3: Antifungals Flashcards

1
Q

What is the MOA of antifungals and what are the two exceptions to this?

A

They target the cell membrane or cell wall, except for Griseofulvin and Flucytosine

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2
Q

What is Amphotericin B produced by?

A

Streptomyces Nodosus

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3
Q

What is the MOA of amphotericin B?

A

Interaction with sterol of fungal membrane, ergosterol, that results in the loss of intracellular components through depolarization and pore formation

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4
Q

What is the spectrum of Amphotericin B. Is it fungicidal or static?

A

Broad spectrum.

Fungicidal

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5
Q

What is the DOC for most systemic fungal infections?

A

Amphotericin B

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6
Q

What is the likely cause of the toxicities of amphotericin?

A

It binds to human membrane sterols as well as fungal sterols.
Due to either
1) Infusion of drug
2) Reactions occurring over time

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7
Q

What are the infusion related toxicities of Amphotericin B?

A

Immediate.

Chills, fever, muscle spasms, headache, vomiting. May occur with each injection and can be lessened by slowing the infusion rate or decreasing daily dose

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8
Q

What are the toxicities that occur from reactions over time with Amphotericin B?

A
  • Powerful nephrotoxicity agent (dose dependent and can cause irreversible kidney damage)
  • Azotemia (BUN and creatinine elevated)
  • Hepatic failure
  • Hypersensitivity
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9
Q

What is the MOA of Flucytosine?

A

Flucytosine is converted to 5- fluorouracil which interferes with fungal DNA and RNA synthesis

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10
Q

What is the spectrum of Flucytosine?

A

Lower than amphotericin B, used for cryptococcus neoformans, some strains of candida, aspergillosis fumigatus, etc.

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11
Q

What is the DOC for crytococcus infections?

A

Flucytosine plus amphotericin B (significant synergistic effect)

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12
Q

Does Amphotericin B or Flucytosine have better CSF penetration?

A

Flucytosine

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13
Q

What are the toxicities of Flucytosine?

A

Depression of bone marrow, GI disturbace, elevated ALT/AST

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14
Q

What is the MOA of the “-azoles”?

Static or cidal?

A

Inhibits synthesis of ergosterol, leads to depletion of ergosterol and accumulation of toxic sterols causing increased permeability and inhibition of fungal growth.

Fungistatic

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15
Q

What is the spectrum of ketoconazole?

A

Broad spectrum antifungals

Poor CNS penetration

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16
Q

What are the toxicities associated with ketoconazole?

A
  • Potent inhibitor of P450s, drug interactions
  • Gynecomastia and impotence due to inhibition of adrenal and testicular function
  • Prolonged QT
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17
Q

What are the contraindications of Ketoconazole?

A

Hepatic disease

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18
Q

Why is fluconazole used in Fungal meningitis?

A

It penetrates well into body fluids, particularly CSF where drug concentration reaches 50-90%

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19
Q

What are the toxicities associated with Fluconazole?

A
  • Less toxic than amphotericin B or Flucytosine and better tolerated than Ketoconazole
  • Less drug interactions, but potent inhibitor of CYP2C9
  • Headache
20
Q

What is used for suppressive therapy and/or prophylactic therapy in HIV+ patients?

A

Fluconazole

21
Q

How is fluconazole administered?

A

Oral or IV

22
Q

How is Ketoconazole administered?

A

Oral, or available in shampoos and creams

23
Q

How is Voriconazole administed?

A

Oral or IV

24
Q

What is the DOC for Aspergillus?

A

Voriconazole and amphotericin B

25
Q

What are the toxicities associated with Voriconazole?

A

-Drug interactions (potent inhibitor of P450s)
-Genetic polymorphism of CYP2C19
Extensive metabolizer results in low drug concentration
Poor metabolizer results in high drug concentration
-Reversible visual impairment

26
Q

What is the spectrum of Itraconazole?

A

Active against many of the same fungi as ketoconazole and fluconazole, but has greater activity against Apergillus (but not DOC!)

27
Q

What are the toxicities associated with Itraconazole?

A
  • Drug interactions (potent inhibitor of CYP34A)

- GI effects

28
Q

How is itraconazole administered?

A

Oral or IM

29
Q

How does Itraconazole bioavailability change when taken via capsule and oral solution?

A
  • Capsules: 40-50% if administered on empty stomach, 90-100 when administered with meal
  • Oral solution: 55% under fed conditions, increases to 72% under fasting
30
Q

What is the spectrum for Isavuconazonium?

A

Indicated for the treatment of Mucormycosis and invasive aspergillosis

31
Q

What are the toxicities associated with Isavuconazonium?

A
  • Drug interactions (moderate inhibitor of CYP3A4)
  • Nephrotoxicity
  • Decrease in the QT interval
32
Q

What are the contraindications of Isavuconazonium?

A

Patients with familial short QT syndrome

33
Q

What is the spectrum for Posaconazole?

A

Indicated for the treatment of Apergillus and candida

34
Q

What are the toxicites associated with Posaconazole?

A
  • Drug interactions (potent inhibitor of CYP3A4)

- GI upset, stomatitis, vaginal bleeding, hypokalemia, and thrombocytopenia

35
Q

What are the 3 drugs in the Echinocandins class?

A

Caspofungin, Micafungin, and Andulafungin

36
Q

What makes Caspofungin a good treatment option for Apergillosis?

A

Lack of nephrotoxicity and few drug interactions

37
Q

How is caspofungin administered?

A

IV slow infusion

38
Q

What is the MOA of Griseofulvin? Is it cidal or static?

A

Binds to the microtubules of certain fungi. It binds specifically to keratin and prevents infection in new skin. Fungistatic

39
Q

What is the DOC for onychomycosis?

A

Griseofulvin

40
Q

What are the contraindications for griseofulvin?

A
  • Acute intermittent porphyria
  • Hepatocellular failure
  • Pregnancy and men 6 months prior to fathering a child
41
Q

What are the toxicites associated with griseofulvin?

A

GI upset, headache*, disulfiram like effects, hematological disturbances, rashes, photosensitivity, etc

42
Q

What is the MOA of Terbinafine? Is it cidal or static?

A

Interferes with sterol biosynthesis, inhibits squalene monooxygenase, build up of squalene is toxic to fungi.
Fungicidal

43
Q

What is terbinafine used to treat?

A

Less active against candida, but effective for onychomycosis (not DOC).

44
Q

What is nystatin used for?

A

Potent antibiotic used for candidal infections.

45
Q

How is nystatin administered?

A

Orally for GI candida infections and topically for other candida infections

46
Q

What is efinaconazole used for? How it it administered?

A

Onychomycosis of the toenail caused by trichophyton rubrum and trichophyton mentagrophytes
Topical

Pharmacology (25 decks)

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