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Pharm Exam 8 > L13 Antifungals > Flashcards

L13 Antifungals Flashcards

1
Q

How do most antifungals work in a general sense?

A

All except for Griseofulvin and Flucytosine target the cell membrane or wall

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2
Q

What are the major drug classes that are used for systemic fungal infections?

A

Amphotericin B is DOC for all systemic mycoses
Flucytosine
Azoles
Echinocandins

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3
Q

MOA of Amphotericin B

A

Binds to ergosterol in the cell membrane and creates a pore. Does not inhibit synthesis of ergosterol. Fungicidal

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4
Q

Spectrum of Amphotericin B

A

Broad

Some protozoa and Entamoeba also covered

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5
Q

Amphotericin B

Administration, Tissue penetration, Excretion

A

IV only, 6 weeks to 3-4 months
Poor CNS and Aqueous Humor
Slow excretion by the kidney–can cause nephrotoxicity
Renal/Hepatic impairment and hemodialysis have little effect in drug concentration

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6
Q

Amphotericin B Toxicities

A

Because it binds to Ergosterol can also bind weakly to cholesterol in human cell membranes–thought to be cause of toxicities.
Can occur:
1) With infusion: chills, fever, muscle spasms, vomiting, headache; prevented with slower infusion
2) Over time: Nephrotoxicity leading to azotemia (elevated BUN and Creatinine in almost all patients) (don’t combine with other nephrotoxic agents like Aminoglycosides),

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7
Q

MOA of Flucytosine

A

Converted to 5-FU (Fluorouracil) by cytosine deaminase which interferes with fungal DNA and RNA synthhesis
Only Fungi and Bac have the necessary enzyme

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8
Q

What is the DOC for Cryptococcus?

A

Flucytosine

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9
Q

Flucytosine

Administration, tissue penetration, elimination

A

Oral admin.
Differs from Amphotericin B in that it penetrates the CNS and Aqueous humors quite well
Renal elimination–impairment can lead to toxicity

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10
Q

Which anti-fungal agent can cause a depression of bone marrow causing anemia, leukopenia, thrombocytopenia?

A

Flucytosine

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11
Q

What are the toxicities of Flucytosine?

A

Bone marrow depression
GI disturbances (because Bac have the enzyme to convert to 5-FU)
Elevated liver enzymes

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12
Q

Are Azoles static or cidal?

A

Static

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13
Q

MOA of Azoles

A

Inhibit the synthesis of ergosterol and thereby force production of toxic metabolites

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14
Q

Spectrum of Ketoconazole

A

Broad

Think of it like Amphotericin B

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15
Q

Ketoconazole

Admin., tissue penetration, elimination

A

Oral
CNS penetration low, largely bound to albumin
Extensively metabolized by the liver prior to elimination
Serious hepatotoxicity
Shows up in urine, saliva, milk

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16
Q

Ketoconazole toxicity

A

Serious hepatotoxicity
Inhibits P450 enzymes (CYP3A4)
Inhibits adrenal and testicular function
Other azoles often preferred due to decreased drug interactions.

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17
Q

MOA of Fluconazole (Diflucan)

A

Inhibits P450 of fungus blocking ergosterol synthesis
Has a lower affinity for human P450 than Ketoconazole but can still increase levels of phenytoin, cyclosporine, warfarin, etc.

18
Q

Use for Fluconazole

A

Cryptococcal meningitis–penetrates well into CSF
Candidiasis
Prophylaxis in HIV for the above diseases

19
Q

Fluconazole

Admin., tissue distribution

A

Oral or IV

Penetrates well into CSF compared to Ketoconazole

20
Q

Fluconazole toxicity

A

Less toxic than amphotericin B or flucytosine and better tolerated than ketoconazole
Many less drug interactions than other azoles
No inhibition of adrenal or testicular steroidogenesis

21
Q

Itraconazole

Admin., use, metabolism

A

Oral admin. in capsule or solution
Same coverage as other azoles but especially good against aspergillus (though voriconazole is the DOC)
Hepatically metabolized

22
Q

Voriconazole characteristics

A 
Similar to Fluconazole
Oral and IV
Hepatic elimination
Many drug interactions
Visual impairment in 50%
DOC for aspergillus
Unlike Fluconazole good against molds
23
Q

Isavuconazole

A

New antifungal
Treatment of mucormycosis and invasive aspergillosis
IV and oral
Decreases QT interval and is therefore contraindicated in patients with familial short QT

24
Q

Which drug category inhibits the synthesis of fungal cell walls by inhibiting Beta(1,3)-D-glucan synthase?

A

Echinocandins
These include:
Caspofungin, Micafungin, Anidulafungin
Used for esophageal candidiasis and others

25
Q

What drug would be given for invasive aspergillosis in refractory patients and how would it be administered?

A

Caspofungin
IV–slow infusion
also good for esophageal candidiasis

26
Q

What drug is used for prophylaxis of candida in patients undergoing hematopoietic stem cell transplantation?

A

Micafungin

IV admin

27
Q

What are the topical fungal treatments?

A

Griseofulvin (oral admin)
Terbinafine (oral or topical)
Nystatin (oral or topical)

28
Q

What is the DOC for onychomytosis? MOA?

A

Griseofulvin

Binds to the microtubules of fungi and destroys the mitotic spindle structure

29
Q

What makes Griseofulvin unique?

A

Binds to keratin and prevents infection in new skin structures
Requires 6 months to work

30
Q

Griseofulvin contraindications

A

acute intermittent porphyria, hepatocellular failure, pregnancy (teratogenic coming from mother or father)

31
Q

Terbinafine (Lamisil) admin and MOA and use

A

Oral or topical
Interferes with sterol biosynthesis
Effective against onychomycosis–superior to Griseofulvin and itraconazole
Fungicidal against dermatophytes but much less active against candida

32
Q

What is Nystatin primarily used for? MOA?

A

Candida infections

Alters permeability of the cell leading to death–forms pores in the membrane like ampho B

33
Q

Efinaconazole (Jublia)

A

Newest topical fungal drug

Used for onychomytosis of toenails caused by trichophyton sp.

34
Q

Miconazole nitrate (Monistat)

A

Use: trichophyton, epidermophyton, microsporum, candida, cryptococcus, aspergillus

35
Q

Clotrimazole (Lotrimin)

A

Use: dermatophytes, yeasts, Malassezia furfur

36
Q

What is the causative agent of Tinea versicolor?

A

Malassezia furfur

37
Q

Tolnaftate (Tinactin)

A

Tinea versicolor

Not effective for onychomycoses

38
Q

Which drugs inhibit ergosterol production?

A

Terbinafine

Azoles

39
Q

Which drugs form pores in the walls of fungi?

A

Amphotericin B

Nystatin

40
Q

Which drugs act like the penicillins of antifungals and prevent synthesis of the molecules needed to make the cell wall?

A

Echinocandins

Pharm Exam 8 (6 decks)

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