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Yr 2 Gastrointestinal > Wk 2 - Pharmacology: Antifungal Drugs > Flashcards

Wk 2 - Pharmacology: Antifungal Drugs Flashcards

1
Q

List the different types of fungi that cause fungal infections in humans.

A
  • True yeast – single-celled eukaryotic organisms e.g. Cryptococcus
  • Yeast like fungi – non-branching filaments e.g. Candida albicans
  • Filamentous fungi – branching filaments (mycelium) e.g. Aspergillus, dermatophytes (ringworm)
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2
Q

Fungal infections are generally superficial and affect ____ and ____.

A

Fungal infections are generally superficial and affect skin and mucous membranes.

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3
Q

Among immunocompromised individuals, fungal infections present after _____ as _____ infections.

A

Among immunocompromised individuals, fungal infections present after broad-spectrum antibiotic as opportunistic infections.

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4
Q

What are the main types of antifungal drugs?

A
  1. Polyenes
  2. Imidazoles / Triazoles
  3. Others: Flucytosine, Griseofulvin, Terbinafine
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5
Q

Avoidance and good hygiene are a component of…

A

effective treatment of fungal infections

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6
Q

What are the mechanisms of action of antifungal drugs? List three.

A
  1. Cell wall synthesis inhibitors
  2. Nucleic acid synthesis inhibitors
  3. Mitotic spindle
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7
Q

Give examples of antifungal drugs that inhibit cell wall synthesis.

A
  • Polyenes
  • Imidazole
  • Triazoles
  • Terbinafine
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8
Q

Give an example of an antifungal drug that inhibits nucleic acid synthesis.

A

Flucytosine

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9
Q

Give an example of an antifungal drug that acts in the mitotic spindle.

A

Griseofulvin

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10
Q

Most antifungal drugs act as…

A

cell wall synthesis inhibitors

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11
Q

Describe how a fungus makes its cell wall.

A
  1. Squalene (part of cholesterol formation)
  2. Converted into lanosterol (becomes cholesterol) - via squalene epoxidase
  3. In fungi, also made into ergosterol (via lanosterol demethylase)
  4. Ergosterol is incorporated into cell wall of fungi
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12
Q

How do polyenes antifungals work?

A
  • Bind to ergosterol (which makes up fungi cell wall) and compete with it
  • They cause pore generation in fungi membrane
  • Which prevents fungi’s ability in maintaining its environment (loss of K ions mainly)
  • Leading to its death eventually
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13
Q

List some side effects of antifungal polyenes.

A

Side effects:

  • Few because most are used topically
  • Some cause GI upset internally if need to taken orally and also nephrotoxicity
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14
Q

Give examples of polyene antifungals.

A
  • Amphotericin – IV used for systemic fungal infection, most fungi and yeasts – C.albicans
  • Nystatin – C.albicans infection of skin and mucous membranes, oesophageal and intestinal candidiasis
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15
Q

What are imidazoles?

A

Antifungal drugs that inhibit cell wall synthesis

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16
Q

How do imidazoles work?

A
  • Block lanosterol demethylase
  • Removing ergosterol completely
  • Lead to growth arrest
  • Fluidity of cell wall increases, cell permeability increases
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17
Q

What is one side effect of blocking lanosterol demethylase?

A

Enzyme (lanosterol 14a-demethylase) is P450 like, Ketoconazole (antifungal) can also block adrenal gland hormone and steroid formation

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18
Q

What is imidazole used to to treat?

A

Local treatment of vaginal candidiasis, dermatophyte infections

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19
Q

List the three different imidazoles used as antifungals.

A
  1. Clotrimazole
  2. Miconazole
  3. Ketoconazole
20
Q

Clotrimazole (antifungal imidazole) is used to treat…

A
  • Vaginal candidiasis
  • Ring worm
21
Q

Miconazole (antifungal imidazole) is used…

A
  • Locally to treat oral infections
  • For intestinal infections (possible drug interactions)
22
Q

Ketoconazole (antifungal imidazole) is used to treat…

A
  • Systemic mycoses
  • Vulval candiasis
23
Q

Ketoconazole has the best ____ (oral/buccal) absorption.

A

Ketoconazole has the best oral absorption.

24
Q

What are triazoles?

A

Antifungal drugs that inhibit cell wall synthesis via inhibiting lanosterol demethylase from concerting lanosterol to ergosterol (ergosterol is what makes up fungal cell wall)

25
Q

Give three examples of triazoles (antifungal cell wall inhibitors).

A
  1. Fluconazole
  2. Itraconazole
  3. Voriconazole
26
Q

Fluconazole (triazole antifungal) is used for…

A
  • Candida
  • Cryptococcus
27
Q

Fluconazole (triazole antifungal) has the ability to penetrate the…

A

Cerebrospinal fluid

28
Q

Itraconazole (triazole antifungal) is used for…

A
  • Mucocutaneous candidiasis
  • Dermatophytes
29
Q

Voriconazole (triazole antifungal) is used for…

A

Life-threatening aspergillosis

30
Q

What drug is used for life-threatening aspergillosis?

A

Voriconazole

31
Q

Itraconazole is contraindicated in…

A

individuals who take calcium channel blockers (due to increased negative ionotropic effect).

32
Q

What is terbinafine?

A

Antifungal cell wall synthesis inhibitor

33
Q

What is the mechanism of action of terbinafine?

A
  • Blocks squalene epoxidase
  • Stops formation of lansosterol from squalene
  • Leads to membrane disruptions and death
34
Q

Terbinafine is used in treatment of…

A

dermatophyte (ringworm) of the nail

35
Q

What is flucytosine?

A

Antifungal drug

36
Q

How does flucytosine work?

A

Penetrates the fungal cell wall and is converted to 5-fluorouracil which competes with uracil, thus interfering with fungal RNA and protein synthesis.

37
Q

Generally, flucytosine is only used in combination with…

A

Only used in combination with amphotericin (polyene) or fluconazole (triazole)

38
Q

What is griseofulvin?

A

Antifungal that acts on the mitotic spindle

39
Q

What is griseofulvin’s mechanism of action?

A

It is thought to inhibit fungal cell mitosis and nuclear acid synthesis. It also binds to and interferes with the function of spindle and cytoplasmic microtubules by binding to alpha and beta-tubulin.

40
Q

What is griseofulvin used to treat?

A

Mainly prescribed for infections occurring on the skin or scalp

41
Q

What are the three antifungals that are most used?

A
  1. Amphotericin (polyene)
  2. Itraconazole (Triazole)
  3. Fluconazole (Triazole)
42
Q

Name an OTC antifungal.

A

Clotrimazole (imidazole)

43
Q

What is the site of action of most antifungal drugs?

A

Cell wall synthesis inhibitors

44
Q

Triazole blocks the formation of what cell component?

A

Ergosterol via lanosterol demethylase inhibition

45
Q

Griseofulvin is used against which infection?

A

Dermatophytes - ringworms

Yr 2 Gastrointestinal (37 decks)

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