Antifungals Flashcards

1
Q

Polyene antibiotic that binds to Ergosterol and forms pores in the cell wall, leading to ion leakage and cell death

A

Amphotericin B

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2
Q

Antifungal agent with the broadest spectrum of activity, including fungicidal

A

Amphotericin B; used against yeasts, endemic mycoses, and pathogenic molds

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3
Q

Highly insoluble and formulated as deoxycholate colloidal suspension

A

Amphotericin B

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4
Q

PK of Amphotericin B

A

Slow IV infusion (poor oral absorption); Low penetration into CSF; Intrathecal for Meningeal disease

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5
Q

Often used as initial induction regimen to reduce fungal burden, then followed by an Azole

A

Amphotericin B

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6
Q

Preferred treatment for deep fungal infections during prenancy

A

Amphotericin B

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7
Q

AE of Amphotericin B

A

Infusion-related: fever and chills, muscle spasms, vomiting, headache, hypotension

Anemia due to decreased Erythropoietin

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8
Q

Premedication with which drugs may alleviate AE of Amphotericin B?

A

Antihistamines, Glucocorticoids, Antipyretics, or Meperidine

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9
Q

How does Amphotericin B cause renal toxicity?

A

Slow toxicity by binding Cholesterol and forming pores in the mammalian cell membranes

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10
Q

How can renal damage by Amphotericin B be attenuated?

A

Administration of Saline infusion with Amphotericin B

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11
Q

What should be monitored during Amphotericin treatment?

A

Liver and Kidney function, serum electrolytes (Mg and K), blood counts, and hemoglobin

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12
Q

How does Amphotericin B affect the CNS?

A

Slow toxicity: Intrathecal administration can cause seizures and neurological damage

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13
Q

3 Lipid formulations of Amphotericin B

A

Liposomal Amphotericin B (L-AMB)
Amphotericin B Lipid Complex (ABLC)
Amphotericin B Colloidal Dispersion (ABCD)

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14
Q

Why are Lipid formulations of Amphotericin B used?

A

Packaging Amphotericin B in lipid carriers reduces exposure to nephron –> reduces nephrotoxicity

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15
Q

Synthetic Pyrimidine antimetabolite that uses Cytosine permease to enter fungal cells

A

Flucytosine

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16
Q

MOA of Flucytosine

A

Fungistatic; Enters fungal cell via Cytosine permease –> converted to 5-Fluorouracil (5-FU) —> converted to 5-fluorodeoxyuridine monophosphate –> inhibits thymidylate synthase –> no synthesis of dTMP.

Fluorouridine triphosphate (5-FUTP) is also formed –> inhibits protein synthesis

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17
Q

PK of Flucytosine

A

Mammalian cells cannot convert it into its active metabolites

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18
Q

Combination of Flucytosine and which drug gives a synergistic effect?

A

Amphotericin B

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19
Q

Nicknamed the “suicide inhibitor”

A

Flucytosine

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20
Q

Description of Flucytosine

A

Narrow spectrum; used in combination with other drugs for synergism and to avoid resistance

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21
Q

Which drug is combined with Amphotericin B to treat systemic candidiasis and cryptococcosis?

A

Flucytosine

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22
Q

Indications of Flucytosine

A

Candida and/or Cryptococcal infections

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23
Q

AE of Flucytosine

A

Bone marrow toxicity; due to metabolism by intestinal flora to 5-Fluorouracil

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24
Q

Triazoles

A

Itraconazole, Fluconazole, Voriconazole, Posaconazole

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25
Q

Imidazoles

A

Ketoconazole, Miconazole, Clotrimazole

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26
Q

Are Azoles used for Systemic or Superficial mycoses?

A

Systemic mycoses

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27
Q

Classifications of Azoles

A

Imidazoles and Triazoles

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28
Q

MOA of Azoles

A

Azoles inhibit CYP450 enzyme 14-alpha-sterol demethylase, which usually converts Lanosterol to Ergosterol –> disrupts membrane function and increases permeability

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29
Q

Specificity of Azoles is due to a greater affinity for fungal CYP450 enzymes than for human CYP450 enzymes. Which Azoles have greater specificity?

A

Triazoles

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30
Q

AE of Azoles

A

GI upset; relatively non-toxic

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31
Q

PK of Ketoconazole

A

Strong inhibitor of CYP3A4; can potentiate Warfarin and Cyclosporine toxicities

Poor CSF penetration

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32
Q

How do Antacids, H2-blocker, and PPIs affect Ketaconazole absorption?

A

Ketaconazole is best absorbed at low gastric pH; these drugs interfere with absorption

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33
Q

Indications of Ketaconazole

A

Superficial mycoses; narrow spectrum

34
Q

AE of Ketaconazole

A

Decreased testosterone levels, gynecomastia, decreased libido in men, menstrual irregularities

High doses may inhibit adrenal steroid synthesis –> decrease plasma cortisol concentrations

35
Q

PK of Fluconazole

A

High oral bioavailability, good CSF penetration, Oral and IV

36
Q

Drug interactions of Fluconazole

A

Moderate inhibitor of CYP3A4 but strong inhibitor of CYP2C9 –> increased plasma levels of Zidovudine, Phenytoin, and Warfarin

37
Q

Fluconazole has no activity against which type of fungi?

A

Aspergillus and filamentous fungi

38
Q

DOC for Asperigillosis

A

Voriconazole

39
Q

Contraindications of Itraconazole

A

Potentially fatal arrhythmias when given with Cisapride or Quinidine

40
Q

PK of Itraconazole

A

Metabolism by CYP3A4 and strong inhibitor of CYP3A4
Poor CSF penetration
Absorption reduced by antacids, H2-blockers, and PPIs

41
Q

Indications for Itraconazole

A

Dimorphic fungi (Blastomyces, Sporothrix, and Histoplasma), Dermatophytoses, Onchomycosis, and Aspergillus (but replaced by Voriconazole for this)

42
Q

AE of Voriconazole

A

Transient visual disturbances and numerous drug interactions

43
Q

PK of Voriconazole

A

Metabolized by and inhibits CYP2C19, CYP2C9, and CYP3A4

44
Q

Antifungal activity of Posaconazole

A

Zygomycetes such as Mucor

45
Q

Which two Imidazoles have similar spectrum of activity to Itraconazole?

A

Posaconazole and Voriconazole

46
Q

PK of Posaconazole

A

Inhibits CYP3A4

47
Q

Only Systemic Azole with renal elimination (all others are hepatic)

A

Fluconazole

48
Q

Which Systemic Azole has the highest CSF:serum ratio i.e. best CSF absorption?

A

Fluconazole

49
Q

Antifungal activity of Capsofungin

A

Candida and Aspergillus

50
Q

PK of Capsofungin

A

IV

51
Q

MOA of Capsofungin

A

Inhibits synthesis of beta 1-3-D-glucans in the fungal cell wall –> disruption of cell wall and death

52
Q

An Echinocandin

A

Capsofungin

53
Q

MOA of Griseofulvin

A

Disrupts mitotic spindle –> inhibits mitosis

54
Q

Indications of Griseofulvin

A

Treatment of dermatophytosis; replaced by Itraconazole and Terbinafine

55
Q

PK of Griseofulvin

A

Absorption enhanced by fatty meals

56
Q

Drug Interactions of Griseofulvin

A

Induces CYP450 enzymes: increases metabolism of Warfarin, etc.

57
Q

Antifungal Allylamine

A

Terbinafine

58
Q

MOA of Terbinafine

A

Inhibits Squalene epoxidase –> decreased Ergosterol synthesis and toxic accumulation of squalenes in fungal cell

59
Q

Indications of Terbinafine

A

Most effective against Onychomycosis; also used for Tinea cruris and Tinea corporis

60
Q

AE of Terbinafine

A

GI effects, rash, etc.

61
Q

Drug interactions of Terbinafine

A

Doesn’t affect CYP450 –> NO DRUG INTERACTIONS

62
Q

Polyene macrolide Antifungal with similar structure and MOA as Amphotericin B

A

Nystatin

63
Q

Only used for Candidiasis in cutaneous, vaginal, oral administration

A

Nystatin

64
Q

PK of Nystatin

A

Too toxic for IV administration and not absorbed from GI, skin, or vagina –> little toxicity

65
Q

Indication of topical Amphotericin B

A

Cutaneous candidiasis

66
Q

2 Azoles most commonly used topically

A

Miconazole and Clotrimazole; both OTC

67
Q

PK of Terbinafine

A

Accumulates in keratin; available orally or as topical cream

68
Q

Treatment of esophageal candidiasis

A

IV/Oral Fluconazole

69
Q

Treatment of urinary candidiasis

A

IV/Oral Fluconazole

70
Q

Treatment of oropharyngeal candidiasis

A

Mild: topical Clotrimazole or Nystatin
Moderate to severe: Oral Fluconazole
AIDS patient: Oral Fluconazole

71
Q

Treatment of vulvovaginal candidiasis

A

Topical Azoles or Oral Fluconazole

72
Q

Treatment of recurrent vulvovaginal candidiasis

A

Oral Fluconazole

73
Q

Treatment of Candidemia

A

IV Fluconazole or an IV Echinocandin

74
Q

Treatment of cutaneous candidiasis

A

Topical Amphotericin B, topical Azole, or topical Nystatin

75
Q

Treatment of Cryptococcosis

A

Amphotericin B + Oral Flucytosine then Oral Fluconazole

76
Q

Treatment of invasive Aspergillosis

A

IV and then Oral Voriconazole

77
Q

Treatment of Mucormycosis

A

Amphotericin B

78
Q

Treatment of Fusariosis

A

Amphotericin B

79
Q

Treatment of Onychomycosis

A

Oral Terbinafine or Oral Itraconazole or Oral Fluconazole

80
Q

DOC for Pneumocystis jiroveci pneumonia treatment and prophylaxis in immunocompromised

A

Co-trimoxazole

81
Q

Alternative therapies for Pneumocystic jiroveci

A
Clindamycin + Primaquine 
Atovaquone 
Dapsone + Trimethoprim
Pentamidine 
Moderate to severe: also give Prednisone