Chapter 42
Antifungal Drugs
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Fungi



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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
2
Yeasts



Single-cell fungi
Reproduce by budding
Can be used for


Baking
Alcoholic beverages
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
3
Molds


Multicellular
Characterized by long, branching filaments
called hyphae
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
4
Mycotic Infections

Four general types

Cutaneous
 Subcutaneous
 Superficial
 Systemic
• Can be life threatening
• Usually occur in immunocompromised host
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
5
Mycotic Infections (cont’d)

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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
6
Mycotic Infections (cont’d)

Vaginal candidiasis


Yeast infection
Pregnancy, women with diabetes mellitus, women
taking oral contraceptives
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
7
Classroom Response Question
A patient has developed an aspergillosis infection.
Which tissue does the aspergillosis affect?
A.
B.
C.
D.
Skin
Nails
Blood
Lungs
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
8
Antifungal Drugs


Drugs used to treat infections caused by fungi
Systemic


amphotericin B, caspofungin, fluconazole,
voriconazole, terbinafine
Topical

nystatin, terbinafine
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
9
Antifungal Drugs (cont’d)

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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
10
Mechanism of Action

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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
11
Mechanism of Action (cont’d)

griseofulvin



Disrupts cell division
Result: inhibited fungal mitosis (cell division)
Older drug; newer drugs are more commonly used
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
12
Mechanism of Action (cont’d)

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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
13
Mechanism of Action (cont’d)

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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
14
Mechanism of Action (cont’d)

Echinocandins: capsofungin, micafungin, and
anidulafungin

Prevent the synthesis of glucans (essential
components of fungal cell walls)
 Result: fungal cell death
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
15
Indications



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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
16
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)
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
17
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
18
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.
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
19
Antifungal Drugs:
Adverse Effects

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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
20
Antifungal Drugs:
Contraindications




Liver failure
Renal failure
Porphyria (griseofulvin)
Drug allergy
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
21
Antifungal Drugs:
Interactions


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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
22
Nursing Implications



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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
23
Nursing Implications (cont’d)



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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
24
Classroom Response Question
Fifteen 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 infusionrelated reaction.
D. Slow the infusion to reduce these adverse effects.
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
25
Nursing Implications (cont’d)

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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
26
Nursing Implications (cont’d)

Some oral forms should be given with meals to
decrease GI upset; others require an empty
stomach—be sure to check
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
27
Classroom Response Question
A patient is taking nystatin (Mycostatin) in an oral troche
form for oral candidiasis. Which instruction is correct?
A.
B.
C.
D.
Allow the troche to dissolve slowly in the mouth.
Swish the medication in the mouth and then swallow it.
Chew the troche thoroughly to activate the medication.
Swallow the troche whole without chewing.
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
28
Nursing Implications (cont’d)


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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
29
Nursing Implications (cont’d)

Monitor for therapeutic effects




Easing of symptoms of infection
Improved energy levels
Normal vital signs, including temperature
Monitor carefully for adverse effects
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
30