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Fungi
• Fungi are microorganisms that include yeasts and molds
• Most of the time fungi exist in harmony with humans
• Fungal infection is called a mycosis or mycotic infection
• Local or systemic
• Fungi that cause mycoses of the skin and mucous membranes are
called dermatophytes
• Fungi more closely resemble human cells
• Drugs act in a different way than antibacterials
• Usually have more side effects and reactions when taken systemically
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How Fungus Differs from Bacteria
Patients Susceptible to Fungal Infections
• Patients with AIDS and AIDS-related complex (ARC)
• Patients taking immunosuppressant drugs
• Patients who have undergone transplantation surgery or cancer
treatment
• Members of growing elderly population no longer protected from
environmental fungi
• Fungus
• Composed of rigid cell
wall made up of chitin and
polysaccharides, and a
cell membrane containing
ergosterol.
• Protective layers of the
fungal cell make it
resistant to antibiotics
• Conversely, bacteria are
resistant to antifungals
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Antifungal Drugs
Systemic Antifungals
• Administered PO, IV, topically, and vaginally to treat a variety of
mycoses
• 6 Classes:
• Treat systemic fungal infections
• Can be toxic to the host and are not to be used indiscriminately
• Culture and sensitivity testing should be done prior to
prescribing anti-fungal agents
• See table 11.1
•
azoles, polyenes, allylamines, antifungal antibiotics, antimetabolites, and
echinocandins
• May be administered systemically or topically
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Sites of Action of Antifungals
Use of Antifungals Across the Life Span
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Azole Antifungals
Azole Antifungals
• Adverse Effect- Liver toxicity and teratogenic effects
• Drug-Drug Interaction
• Itraconazole has a black box warning regarding the
potential for serious cardiovascular
effects with lovastatin, simvastatin, triazolam,
midazolam, pimozide, or dofetilide.
• Inhibits CYP450 enzyme system
• cyclosporine, digoxin, oral hypoglycemics, warfarin,
oral anticoagulants, and phenytoin.
• Ergotism with ergot alkaloids
• Indications – Systemic & topical fungal infections
• less toxic than amphotericin B but also less effective
• fluconazole (Diflucan), itraconazole (Sporanox), ketoconazole (Nizoral),
posaconazole (Noxafil), terbinafine (Lamisil), voriconazole (Vfend),
isavuconazonium (Cresemba)
• MOA- Bind to sterols and can cause cell death (fungicidal); inhibit
glucan synthesis (fungistatic)
• Pharmacokinetics – Absorbed rapidly from the GI tract,
metabolized in the liver and excreted in urine and feces
• Contraindications – Hepatic and renal dysfunction,
pregnancy and lactation and drugs that prolong the QTc
interval (e.g. ergot-alkaloids)
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Other Antifungal Agents
Echinocandin Antifungals
• Amphotericin B (Abelcet, AmBisome) –
• Indications – Systemic & topical fungal infections
• binds to the sterols in the fungus cell wall-changes
permeability
• fungicidal effect or fungistatic effect
• reserved for progressive, potentially fatal infections
due to serious adverse effects
• anidulafungin (Eraxis), caspofungin (Cancidas), and micafungin (Mycamine).
• MOA – Inhibit glucan synthesis leading to death of the cell wall
• Pharmacokinetics – Given IV, rapid onset, metabolized degradation and
excreted in feces
• Flucytosine (Ancobon)
• Contraindications – Hepatic /renal dysfunction, pregnancy and lactation
• Alters cell membrane leading to death
• Adverse Effects - Liver toxicity, tetrogenic effects and bone marrow
supression
• Griseofulvin (Gris-Peg)
• Drug-Drug Interaction- Cyclosporine
• Changes cell permeability
• Nystatin (generic)
• binds to sterols in the cell wall, changes membrane
permeability
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Other Antifungal Agents - Pharmacokinetics
• Amphotericin B (Abelcet, AmBisome) –
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•
Other Antifungal Agents Contraindication/Cautions
• Amphotericin B (Abelcet, AmBisome) –
• Differentiate the brand used as the dosages vary
• Use cautiously in pregnancy; avoid in renal impairment
• Contraindicated in lactation
• Flucytosine
• extreme caution in renal impairment
• use during pregnancy and lactation only if the benefits
clearly outweigh risks
• Nystatin
• Do not use in pregnancy or lactation unless benefits clearly
outweigh risks.
• IV form, excreted in urine
Flucytosine (Ancobon)
• IV form, excreted in the urine; PO form well
absorbed in GI tract, excreted unchanged in the
urine and feces
Griseofulvin (Gris-Peg)
PO; metabolized in the liver; excreted in urine.
•Nystatin (generic)
• Not absorbed from the GI tract; passes
unchanged in the stool
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Other Antifungal Agents: Drug-Drug Interactions
Other Antifungal Agents: Adverse Effects
• Amphotericin B and other nephrotoxic drugs (such as) – increased risk
of severe renal impairment,
• Cyclosporine, or corticosteroids and other liver enzyme inhibitors
• Hepatotoxicity,
• Nephrotoxicity (severe for amphotericin B)
• Bone marrow suppression
• Rash/dermatological changes
• N, V, D, anorexia, weigh loss
• Pain at injection site – phlebitis/thrombophlebitis
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Topical Antifungals
Nursing Considerations for Systemic
Antifungal Agents
• Indication and MOA- Alter the cell permeability of the fungus,
prevent replication, leading to fungal death, indicated only for local
treatment of mycoses, including tinea infections
• Assess:
• clotrimazole (Lotrimin, Mycelex), econazole (Ecoza), efinaconazole (Jublia),
ketoconazole (Extina, Nizoral, Xolegel), miconazole (Lotrimin AF, Monistat-3),
• History of allergy to antifungal
• Physical status
• Culture of the infected area
• Renal and hepatic function tests and CBC
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• Pharmacokinetics- not absorbed systemically, so do not undergo
metabolism or excretion
• Contraindications- Limited to known allergy to any of these drugs
• Adverse Effects - Irritation, burning, rash, and swelling at the site
• Drug-Drug Interactions - Unknown
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Nursing Considerations for Topical
Antifungal Agents
Assess:
• Known allergy to any topical antifungal agent
• Physical status
• Culture and sensitivity testing
• Area of application for color, temperature, and evidence of lesions
Teach:
• How to apply
• Care of the site
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