Chapter 42

Antifungal Drugs

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Very large and diverse group of microorganisms, including yeasts and molds

Fungal infections also known as mycoses Some fungi are part of the normal flora of the

skin, mouth, intestines, and vagina

Fungi

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Single-cell fungi Reproduce by budding Can be used for

Baking Alcoholic beverages

Yeasts

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Multicellular Characterized by long, branching filaments

called hyphae

Molds

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Four general types Cutaneous Subcutaneous Superficial Systemic

• Can be life threatening

• Usually occur in immunocompromised host

Mycotic Infections

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Candida albicans May follow antibiotic therapy, antineoplastics,

or immunosuppressants (corticosteroids) May result in overgrowth and systemic infections Growth in the mouth is called thrush or oral

candidiasis Common in newborn infants and

immunocompromised patients

Mycotic Infections (cont’d)

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Vaginal candidiasis Yeast infection Pregnancy, women with diabetes mellitus, women

taking oral contraceptives

Mycotic Infections (cont’d)

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Classroom Response Question

A patient has developed an aspergillosis infection. Which tissue does the aspergillosis affect?

A.Skin

B.Nails

C.Blood

D.Lungs

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Drugs used to treat infections caused by fungi Systemic

amphotericin B, caspofungin, fluconazole, voriconazole, terbinafine

Topical nystatin, terbinafine

Antifungal Drugs

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Broken down into major groups based on their chemical structure: Polyenes: amphotericin B and nystatin Imidazoles: ketoconazole Triazoles: fluconazole, itraconazole, voriconazole Echinocandins: caspofungin, micafungin Drugs that are listed individually, not by chemical

structure:• griseofulvin, flucytosine

Antifungal Drugs (cont’d)

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flucytosine Also known as 5-fluorocytosine (antimetabolite) Taken up by fungal cells and interferes with DNA

synthesis Result: fungal cell death Older drug; newer drugs are more commonly used

Mechanism of Action

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griseofulvin Disrupts cell division Result: inhibited fungal mitosis (cell division) Older drug; newer drugs are more commonly used

Mechanism of Action (cont’d)

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Polyenes: amphotericin B and nystatin Bind to sterols in cell membrane lining Result: fungal cell death Do not bind to human cell membranes or kill human

cells

Mechanism of Action (cont’d)

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Imidazoles and triazoles: ketoconazole, fluconazole, itraconazole, voriconazole Inhibit fungal cell cytochrome P-450 enzymes,

resulting in cell membrane leaking Result: altered cellular metabolism and fungal cell

death

Mechanism of Action (cont’d)

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Echinocandins: capsofungin, micafungin, and anidulafungin Prevent the synthesis of glucans (essential

components of fungal cell walls) Result: fungal cell death

Mechanism of Action (cont’d)

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Systemic and topical fungal infections Drug of choice for the treatment of many severe

systemic fungal infections is amphotericin B Choice of drug depends on type and location of

infection

Indications

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Classroom Response Question

A patient is diagnosed with onychomycosis. The nurse anticipates use of which medication for the treatment of this condition?

A.terbinafine (Lamisil)

B.voriconazole (Vfend)

C.fluconazole (Diflucan)

D.amphotericin B (Amphocin, Fungizone)

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Adverse Effects: Amphotericin B

Cardiac dysrhythmias Neurotoxicity; tinnitus; visual disturbances; hand

or feet numbness, tingling, or pain; convulsions Renal toxicity, potassium loss, hypomagnesemia Pulmonary infiltrates Fever, chills, headache, nausea, occasional

hypotension, gastrointestinal upset, anemia

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Classroom Response Question

A patient is receiving amphotericin B lipid complex. The nurse knows that an advantage of the lipid formulations of this drug is that they

A.have a lower cost.

B.can be administered quickly.

C.take longer to be absorbed.

D.cause fewer adverse effects.

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fluconazole Nausea, vomiting, diarrhea, stomach pain, Increased liver enzymes Use with caution in patients with renal and liver

dysfunction nystatin

Nausea, vomiting, anorexia, diarrhea, rash

Antifungal Drugs: Adverse Effects

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Liver failure Renal failure Porphyria (griseofulvin) Drug allergy

Antifungal Drugs: Contraindications

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Many antifungal drugs are metabolized by the cytochrome P-450 enzyme system

Coadministration of two drugs that are metabolized by this system may result in competition for these enzymes, and thus higher levels of one of the drugs

Antifungal Drugs: Interactions

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Before beginning therapy, assess for hypersensitivity, possible contraindications, and conditions that require cautious use

Obtain baseline VS, CBC, liver and renal function studies, and ECG

Assess for other medications used (prescribed and over-the-counter) to avoid drug interactions

Nursing Implications

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Follow manufacturer’s directions carefully for reconstitution and administration

Monitor vital signs of patients receiving IV infusions every 15 to 30 minutes

During IV infusions, monitor I&O to identify adverse effects

Nursing Implications (cont’d)

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Classroom Response QuestionFifteen minutes after an infusion of amphotericin B was started, the patient begins to complain of fever, chills, muscle pain, and nausea. His heart rate has increased slightly, but his blood pressure is down to 100/68. What is the nurse’s priority?

A.Notify the prescriber immediately.

B.Recognize an impending anaphylactic reaction and stop the infusion.

C.Assess for other symptoms of this expected infusion-related reaction.

D.Slow the infusion to reduce these adverse effects.

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amphotericin B To reduce the severity of the infusion-related

reactions, pretreatment with an antipyretic (acetaminophen), antihistamines, antiemetics, and corticosteroids may be given

Use IV infusion pumps and the most distal veins possible

Nursing Implications (cont’d)

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Some oral forms should be given with meals to decrease GI upset; others require an empty stomach—be sure to check

Nursing Implications (cont’d)

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Classroom Response Question

A patient is taking nystatin (Mycostatin) in an oral troche form for oral candidiasis. Which instruction is correct?

A.Allow the troche to dissolve slowly in the mouth.

B.Swish the medication in the mouth and then swallow it.

C.Chew the troche thoroughly to activate the medication.

D.Swallow the troche whole without chewing.

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Nystatin given as an oral lozenge or troche should be slowly and completely dissolved in the mouth (not chewed or swallowed whole)

Nystatin suspension should be swished thoroughly in the mouth as long as possible before swallowing

Nursing Implications (cont’d)

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Monitor for therapeutic effects Easing of symptoms of infection Improved energy levels Normal vital signs, including temperature

Monitor carefully for adverse effects

Nursing Implications (cont’d)

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