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(mul) pharmacology > (Ch 42) Antifungal Drugs > Flashcards

(Ch 42) Antifungal Drugs Flashcards

1
Q

What is the structure of a fungus?

A

Fungi are eukaryotic organisms with rigid cell walls that contain chitin as well as polysaccharides.

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2
Q

What is a mycosis?

A

Fungal infection which can be divided into

three groups:

  • systemic mycoses,*
  • subcutaneous mycoses,*
  • superficial mycoses.*
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3
Q

Name seven drugs used for

systemic and subcutaneous mycoses.

A
  1. Amphotericin B (Fungizone)
  2. Flucytosine (Ancobon)
  3. Ketoconazole (Nizoral)
  4. Fluconazole (Diflucan)
  5. Itraconazole (Sporanox)
  6. Voriconazole (VFEND)
  7. Caspofungin (Cancidas)
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4
Q

Name the 5 different

CLASSIFICATION OF ANTIFUNGAL DRUGS

A
  1. Polyene Antibiotics
  2. Azole Derivatives
  3. Allylamine Drugs
  4. Echinocandin Drugs
  5. Other Antifungal Drugs
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5
Q

Name all

Polyene Antibiotics

A

Amphotericin B

(ABELCET, AMBISOME, AMPHOTEC)

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6
Q

Name all 6

Azole Derivatives:

A
  1. Clotrimazole (GYNE-LOTRIMIN, MYCELEX)b
  2. Fluconazole (DIFLUCAN)
  3. traconazole (SPORANOX)
  4. Ketoconazole (NIZORAL)
  5. Voriconazole (VFEND)
  6. Posaconazole (NOXAFIL)
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7
Q

Name all

Allylamine Drugs

A

• Terbinafine (LAMISIL)c

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8
Q

Name all

Echinocandin Drugs

A

• Caspofungin (CANCIDAS)d

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9
Q

Name all

“Other Antifungal Drugs”

A
  1. Ciclopirox (LOPROX)
  2. Flucytosine (ANCOBON)
  3. Griseofulvin (GRIS-PEG)
  4. Tolnaftate (TINACTIN)
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10
Q

Systemic mycoses

can cause?

A

Systemic mycoses can cause

signs and symptoms of:

soft tissue infection, urinary tract infection, pneumonia, meningitis, or septicemia

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11
Q

The systemic mycoses are most commonly caused by members of the genera?

A

Aspergillus

Blastomyces

Candida

Coccidioides

Cryptococcus

Histoplasma

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12
Q

Echinocandin Drugs

What is the MOA

Ex. of the drug

A

Cyclic hexapeptide compounds that inhibit

fungal cell wall sysntesis

ex: Caspofungin

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13
Q

AMPHOTERICIN B

What is the classification of this drug?

A

Amphotericin B is a

polyene antibiotic

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14
Q

AMPHOTERICIN B

What is its importance?

A

It is the drug of choice for treating many

systemic mycotic infections.

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15
Q
  • Provide examples of*
  • Systemc mycotic infections:*
A

signs and symptoms of soft tissue infection:

urinary tract infection

pneumonia

meningitis

septicemia

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16
Q

Amphotericin B

How does this drug work?

A

Fungal cells contain ergosterol, a sterol specific to fungal cell membranes.

Amphotericin B binds to ergosterol* and *forms pores or channels within the membrane.

This allows electrolytes to leak from the cell*, which *results in cell death

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17
Q

Does amphotericin B bind to

cholesterol?

A

No.

Only ergosterol is affected by this drug.

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18
Q

Does amphotericin B enter the

CNS?

A

No

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19
Q

Amphotericin B

What is this drug’s antifungal spectrum?

A

Amphotericin B is effective against a broad spectrum of organisms including:

Candida
Histoplasma capsulatum

Cryptococcus neoformans

Blastomyces dermatitidis

Aspergillus
Coccidioides immitis

Mucormycosis

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20
Q

Amphotericin B

What is the route of administration?

A

Usually IV;

however, for fungal meningitis:

intrathecal (inject into spinal cord) administration is required.

-A topical form of amphotericin B also exists.

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21
Q

Amphotericin B

What are its pharmacokinetics?

A

Amphotericin B is poorly absorbed from the gastrointestinal tract.

Bile is the major route of excretion. A small part of the drug, however, is eliminated in the urine.

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22
Q
  • Amphotericin B*
  • How does resistance occur?*
A

ergosterol is replaced with other precursor sterols

for the cell membrane.

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23
Q

Amphotericin B

What are adverse signs to watch for during administration?

A
  1. Renal impairment—80% of patients exhibit a decreased glomerular filtration rat*_e and _*changes in renal tubular function.
  2. This drug can cause a renal tubular acidosis.
  3. Newer liposomal formulations of amphotericin B can help reduce the renal toxicity.
  4. Hypotension
  5. Fever, chills (“shake and bake” syndrome)
  6. Hypochromic normocytic anemia
  7. Neurological effects
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24
Q

FLUCYTOSINE

What type of drug is flucytosine?

A

A synthetic pyrimidine antimetabolite.

It is related in structure to an anticancer drug called 5-fluorouracil (5-FU).

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25
Q

Flucytosine

When is it used?

A

Flucytosine is used predominantly in conjunction with amphotericin B

or

itraconazole

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26
Q

Flucytosine

How does flucytosine work?

A

It enters fungal cells through a cytosine- specific permease and is first converted to 5-FU. Subsequently, it is converted to

5- fluorodeoxyuridine monophosphate (5- FdUMP).

This acid inhibits thymidylate synthetase, which is an essential enzyme in the production of DNA .

NOTE: Mammalian cells do not convert flucytosine to 5-FU and therefore are not affected.

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27
Q

Flucytosine

Is its antifungal spectrum broad or narrow?

A

Narrow;

it affects only the following:

Candida
Cryptococcus neoformans

Agents causing chromomycosis

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28
Q

How is flucytosine usually

administered?

A

PO

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29
Q

What are the pharmacokinetics of

flucytosine?

A

Flucytosine distributes well throughout the tissues*, including the *cerebrospinal fluid (CSF).

It is excreted intact in the urine.

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30
Q

Flucytosine

What are the toxicities of this drug?

A

1. Hematological—reversible bone marrow depression leading to neutropenia and thrombocytopenia

  1. Elevated hepatic enzymes
  2. Gastrointestinal disturbances—nausea,

vomiting, severe enterocolitis

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31
Q

Ketokonazole

Into what category does this drug fit?

A

Ketoconazole is the prototypical azole* used for *systemic mycoses.

Other drugs in this category include:

fluconazole, itraconazole, and voriconazole.

They all have the same mechanism of action but different therapeutic indications* and *pharmacokinetics.

Their development provided a way to treat systemic infections orally.

32
Q
  • Ketokonazole*
  • azoles MOA?*
A

They block cytochrome P-450–mediated lanosterol demethylation to ergosterol.

The specific enzyme that is blocked is called C-14-α demethylase.

33
Q

What is ketoconazole’s spectrum?

A

It is useful and mostly used as a second line agent against Histoplasma, Candida, Cryptococcus, Blastomyces, and dermatophytes.

It has largely been replaced by itraconazole for the treatment of all mycoses because of increased effectiveness and reduced toxicities.

34
Q

ketoconazole’s

How is this drug administered?

A

PO -ONLY

35
Q

Ketoconazole

  • What are its pharmacokinetics?*
  • Name 2 drugs that impair its absorption.*
A

Ketoconazole depends on gastric acidity to be dissolved and absorbed;

drugs such as cimetidine and antacids impair its absorption.

Ketoconazole is _metabolized in the liver_ and excreted through the bile.

36
Q

What are ketoconazole’s major toxicities?

A

-Gynecomastia and decreased libido due to inhibition of testosterone* and *cortisol synthesis

-GI distress—nausea, vomiting

-Hepatic dysfunction—inhibits cytochrome P-450 system

-Allergies

37
Q

Ketaconazole

State contraindications to the use of this drug

A

Never use ketoconazole and amphotericin B together

—they antagonize each other’s actions.

38
Q

Fluconazole

What are the major advantages of

fluconazol*_e over _*ketoconazole?

A

Fluconazole can enter the CSF in high concentrations* and *is not dependent on

acidic pH for absorption.

It also does not cause the endocrine dysfunction seen with ketoconazole.

39
Q

What are the therapeutic uses of

fluconazole?

A

-Disseminated or progressive coccidioidal infections such as meningitis—(drug of choice)

-Disseminated histoplasmosis
Oral, esophageal, and vaginal candidiasis.

  • -Candidemia of the nonimmunosuppressed patient.*
  • -Prophylaxis of cryptococcal meningitis in AIDS patients whose infection has been controlled by amphotericin B*
40
Q

Ketoconazole

How is it administered and excreted?

A

Orally** or **IV

Eliminated through the

kidneys.

41
Q

What t_oxicities_ are associated with

Fluconazole?

A

Can inhibit the cytochrome P450 system responsible for the metabolism of several other drugs such as cyclosporine, warfarin, and phenytoin

Similar to most azoles,

do not administer to pregnant women.

42
Q
A
43
Q

ITRACONAZOLE

What is itraconazole’s therapeutic use?

A

Itraconazole is the drug of choice for patients with indolent nonmeningeal infections of:

blastomycosis, histoplasmosis, coccidioidomycosis and cutaneous sporotrichosis.

44
Q

ITRACONAZOLE

Is it effective in CNS infections?

A

No,

it does not easily penetrate the

blood- brain barrier.

45
Q

ITRACONAZOLE

How can this drug be administered?

A

IV or oral

46
Q

ITRACONAZOLE

Where is it metabolized?

A

In the liver.

It is a potent inhibitor of the

cytochrome P450 system.

47
Q

What are the adverse effects of

itraconazole?

A
  • GI distress, hypertriglyceridemia, rash, hypokalemia, hypertension, and hepatotoxicity.*
  • It does not have the endocrinological side effects of ketoconazole.*
48
Q

VORICONAZOLE

When is voriconazole used?

A

This is one of the newer azoles with a broader spectrum than its predecessors.

Currently it is reserved for use in:

invasive Aspergillosis,

life-threatening infections with Fusarium

or

Scedosporium apiospermum.

49
Q

VORICONAZOLE

How is it administered?

A

Oral or IV

50
Q

VORICONAZOLE

How is it metabolized?

A

Through the cytochrome P450 system.

Drugs that induce* or *inhibit that system* can *cause dramatic changes in plasma concentrations of voriconazole.

Coadministration of rifampin or rifabutin is contraindicated

because of increased voriconazole metabolism.

51
Q

VORICONAZOLE

What are its Adverse effects?

A

Transient blurred vision or color perception has been reported shortly after administration.

Hepatotoxicity occurs occasionally.

Rash

52
Q

CASPOFUNGIN

What is it?

A

This drug is the prototype of a class of antifungals called echinocandins.

53
Q

CASPOFUNGIN

MOA

A

It inhibits cell wall synthesis by blocking the formation of β(1,3)-D-glucan.

54
Q

CASPOFUNGIN

Administration?

A

IV- Only

55
Q

CASPOFUNGIN

USE:

A

Invasive Aspergillus infections

for patients who have failed therapy with other agents such as amphotericin B or Voriconazole.

56
Q

Caspofungin

any adverse effects?

A

Yes

phlebitis at the injection site

and

flushing from histamine release

57
Q
  • Identify six major drugs*
  • used to treat*

superficial mycotic infections

A
  1. Griseofulvin(Fulvicin)
  2. Nystatin(Mycostatin)
  3. Miconazole(Monistat)
  4. Clotrimazole(Canestencream)
  5. Econazole(Spectazole)
  6. Terbinafine(Limisil)
58
Q

GRISEOFULVIN

What is its mode of action?

A

Griseofulvin enters susceptible fungal cells and inhibits microtubule function.

With long-term therapy (weeks to months), this drug accumulates in the newly synthesized stratum corneum, making these cells undesirable for fungal growth.

59
Q

GRISEOFULVIN

What is the antifungal spectrum of this drug?

A

It is effective only against dermatophytes, including Trichophyton, Microsporum, and Epidermophyton.

Griseofulvin has largely been replaced by terbinafine because it requires 6 to 9 months of therapy and is more toxic.

60
Q

GRISEOFULVIN

What are the pharmacokinetics of this drug?

A

Griseofulvin is absorbed well orally, especially with a high-fat diet,

and

distributed to the keratin-containing stratum corneum.

It is eliminated through the bile.

61
Q

GRISEOFULVIN

State this drug’s adverse effects.

A

Headache
Hepatotoxicity
GI irritation
Rarely teratogenic or carcinogenic

62
Q

NYSTATIN

What is the structure of drug?

A

Nystatin is a polyene s_imilar in structure_ to amphotericin B, with the same mechanism of action. It creates pores in the cell membrane of the fungi.

63
Q

NYSTATIN

What is the route of administration?

A

Topical for skin and mucocutaneous infections or oral for thrush

Note: Thrush, 0ral candidiasis, is a yeast/fungi infection of the genus Candida that develops on the mucous membranes of the mouth.

happens most often to toddlers and children but can affect anyone. Antifungal medications, which are generally taken for 10 to 14 days, to treat thrush

64
Q

NYSTATIN

What is nystatin’s therapeutic use?

A

Treatment of superficial Candida infections

65
Q

NYSTATIN

What are its adverse effects?

A

Bitter taste

nausea

66
Q

Miconazole-Clotrimazole-Econazole

ROA?

A

Topical.

They are highly toxic if used systemically.

67
Q

Miconazole-Clotrimazole-Econazole

Are other azole drugs

used topically?

A

Yes.

Terconazole and butoconazole

are two of the more recently developed drugs, but they are all very similar drugs.

68
Q

Miconazole-Clotrimazole-Econazole

What are the indications for use?

A

Superficial infections of the skin and mucous membranes (vulvovaginitis).

Effective against Candida and dermatophytoses

69
Q

Miconazole-Clotrimazole-Econazole

  • What are the pharmacological properties*
  • of these drugs?*
A

They are very similar to ketoconazole in mechanism of action and spectrum.

70
Q

Miconazole-Clotrimazole-Econazole

What are the side effects?

A

Since they are only given topically the most common adverse effects include

itching, erythema, and burning.

71
Q

TERBINAFINE

What is it used for?

A

Terbinafine is a first-line agent used to treat dermatophyte infections,

especially onychomycosis

72
Q

TERBINAFINE

What is its route of administration?

A

Although it is used to treat superficial infections,

it is given

orally or topically

73
Q

Terbinafine

How does it work?

A

Inhibits an enzyme (squalene epoxidase) used to synthesize ergosterol.

Accumulation of squalene is toxic to fungi

74
Q

Terbinafine

What are the toxic effects?

A
  • Rash, headache and GI irritation.*
  • Rarely* hepatotoxicity and neutropenia may occur. The drug is contraindicated in pregnancy.
75
Q
A

(mul) pharmacology (18 decks)

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