Antifungals Flashcards

1
Q

Types of Fungal infections

A
  1. Superficial mycoses- Affects skin, mucous membranes, hair & nails
  2. Subcutaneous mycoses- Affects dermis, subcutaneous tissues & adjacent bone
  3. Systemic mycoses- Affects internal organs
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2
Q

MC Systemic fungal infections

A
  1. Candidiasis
  2. Cryptococcosis
  3. Aspergillosis
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3
Q

hjd

A
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4
Q
A

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5
Q

Classification of Antifungals by MOA

A
  1. Alter cell membrane permeability
    - Polyenes
    - Azoles
    - Allylamines
  2. Block Nucleic acid synthesis
    - Flucytosine
  3. Disrupt microtubule function
    - Griseofulvin
  4. Disrupt fungal cell wall
    - Echinocandins
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6
Q

Classification of Antifungals by Clinical use

A
  1. Drugs for Subcutaneous & Systemic mycoses
    - Systemic drugs = Amphotericin B, Flucytosine, Azoles & Echinocandins
  2. Drugs for superficial mycoses
    - Systemic drugs
    - Topical drugs
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7
Q

Amphotericin B MOA

A

Binds to Ergosterol –> Forms pores in cell membrane –> Leakage of intracellular ions & macromolecules –> Cell death

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8
Q

Amphotericin Activity

A
  • Broadest spectrum

- Activity against Clinical significant yeasts, Organisms causing endemic mycoses & Pathogenic molds

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9
Q

Pharmacokinetics of Amphotericin B

A
  • Highly insoluble
  • Poor GI absorption = MUST be IV
  • Low CSF Penetration = Intrathecal therapy necessary for meningitis
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10
Q

Uses of Amphotericin B

A
  • Nearly all life-threatening fungal infections

- Used as initial induction to rapidly reduce fungal burden –> Pts, then continue w/ an azole

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11
Q

Infusion- related AEs of Amphotericin B

A
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12
Q

Other/ Slow toxicity AEs of Amphotericin B

A
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13
Q

Lipid formulations of Amphotericin B

A

Developed to reduce Nephrotoxicity

  1. Liposomal Amphotericin B (L-AMB)
  2. Amphotericin B Lipid Complex (ABLC)
  3. Amphotericin B colloidal Dispersion (ABCD)
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14
Q

MOA of Flucytosine

A

Taken up by fungal cells via Cytosine Permease –> Converted intracellularly to 5-flurouracil (5-FU) –> Converted to 5-fluorodeoxyuridine monophosphate (5-FdUMP)
- Also forms Fluorouridine Triphosphate (5-FUTP)

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15
Q

Actions of %- Fluorodeoxyuridine Monophosphate (5-FdUMP)

A

Inhibits Thymidylate Synthetase –> Blocks dTMP synthesis/ Inhibits DNA synthesis

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16
Q

Actions of Fluorouridine Triphosphate (5-FUTP)

A

Inhibits protein synthesis

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17
Q

Why is Flucytosine & Amphotericin B combined

A

Mammalian cells are unable to convert the parent drug to its active metabolite

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18
Q

Specrum of Flucytosine

A
  • Fungistatic
  • Narrow spectrum
  • NEVER used as single agent - Avoid resistence
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19
Q

Uses of Flucytosine

A
  • Serious infections caused by susceptible strains of Candida &/or Cryptococcus

USED w/ Amphotericin B to avoid resistance

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20
Q

AEs o Flucytosine

A
  • Bone marrow toxicity

Results from metabolism to 5-fluorouracil

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21
Q

Classification & names of Azoles

A
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22
Q

MOA of Azoles

A

Inhibits 14-a-sterol demethylase –> Dec Ergosterol synthesis –> Disrupt membrane function –> Inc permeability

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23
Q

Ergosterol synthesis

A

Conversion of Lanosterol to Ergosterol by the fungal Cytochrome P450 enzyme 14-a-sterol Demethylase

24
Q

AEs of Azoles

A
  • Relatively non-toxic

- Minor GI upset

25
Q

MOA of Ketoconazole

A
26
Q

Uses of Ketoconazole

A
27
Q

Pharmocokinetics of Fluconazole

A
28
Q

Uses of Fluconazole

A
29
Q

Pharmacokinetics of Itraconazole

A
  • Metabolized by CYP3A4
  • Strong CYP3A4 Inhibitor
  • Poor bioavailability
  • Poor CSF penetration
  • Absorption dec. by Antacids, H2 blockers, & PPI
30
Q

Uses of Itraconazole

A
31
Q

AEs of Itraconazole

A

Fatal arrhythmias when given w/ Cisapride or Quinidine

32
Q

Spectrum of Voriconazole

A

Similar to Itraconazole

33
Q

Uses of Voriconazole

A

DOC for Invasive aspergillosis

34
Q

AEs of Voriconazole

A
  • Transient visual disturbances
35
Q

Spectrum of Posaconazole

A

Similar to Itraconazole + Activity against Zygomycetes (eg. Mucor)

36
Q

Pharmacokinetics of Posaconazole

A

Inhibits CYP3A4

37
Q

Properties of Systemic Azoles

A
38
Q

Names of Echinocandins

A

Caspofungin

39
Q

MOA of Caspofungin

A

Inhibits 1-3-D-glucans synthesis in fungal cell wall –> Cell death

40
Q

Spectrum of Caspofungin

A
  • Active against CANDIDA & ASPERGILLUS

- NO activity against Cryptococcus neoformans

41
Q

Pharmacokinetics of Caspofungin

A
  • IV only

- Large cyclic peptides linked to long-chain fatty acids

42
Q

Names of Systemic Drugs used for Superficial mycoses

A
  1. Griseofulvin
  2. Terbinafine
  3. Ketoconazole
  4. Fluconazole
  5. Itraconazole
43
Q

MOA of Griseofulvin

A

Disrupts mitotic spindle –> Inhibits Mitosis

44
Q

Uses of Griseofulvin

A
  1. Dermatophytosis only (Severe cases of skin, hair & nails)

- Replaced largely by Itraconazole & Terbinafine

45
Q

Pharmacokinetics of Griseofulvin

A
  • Absorption improved when given w/ fatty foods

- P450 Inducer - Inc metabolism of other drugs like warfarin

46
Q

MOA of Terbinafine

A

Inhibits Squalene Epoxidase –> Inhibits Ergosterol synthesis & Cause toxic level accumulation of squalene in fungal cells

47
Q

Uses of Terbinafine

A
  • Onychomycosis
48
Q

AEs of Terbinafine

A
  • GI upset
  • Rash
  • Headache
  • Taste disturbance
  • Inc serum liver transaminases
49
Q

Pharmacokinetics of Terninafine

A
  • Inhibits CYP2D6
  • Causes Inc liver transaminases
  • Allylamine
  • ORAL
50
Q

Names of Topical drugs used for Superficial Mycoses

A
  1. Nystatin
  2. Amphotericin B
  3. Clotrimazole
  4. Miconazole
  5. Ketoconazole
  6. Terbinafine
51
Q

Pharmacokinetics of Nystatin

A
  • Oral/ Vaginal or Cutaneous (too toxic for IV)
  • NO GI, skin or vagina absorption –> Little toxicity
  • Similar to Amphotericin B MOA & structure
  • Polyene macrolide
52
Q

Uses of Nystatin

A

Candidiasis ONLY

53
Q

Topical use of Terbinafine

A

Tinea cruris & Tinea corporis

- Topical cream

54
Q

Topical Azoles

A

Clotrimazole & Miconazole (MC used)

- OTC

55
Q

Treatment for

A