CHAPTER 35
DRUGS FOR FUNGAL, PROTOZOAL, AND
HELMINTHIC INFECTIONS
LEARNING OUTCOME 1
Compare and contrast the pharmacotherapy of superficial and systemic fungal infections.
Concepts
Fungi are single-celled or multicellular organisms. They are more complex than bacteria and include
mushrooms, yeasts, and molds; their purpose is to decompose dead organisms. (See Table 35.1 for a list of
fungi.) Humans are exposed to fungi when they handle contaminated soil or inhale spores. Fungal infections are
classified as superficial or systemic. The superficial infections affect hair, skin, nails, and mucous membranes
and are treated with topical agents. The systemic infections affect internal organs, are less common, and can be
fatal in immunosuppressed patients; systemic infections are treated with oral or parenteral agents. Fungi are
unaffected by most antibiotics.
LEARNING OUTCOME 2
Identify the types of patients who are at greatest risk for acquiring serious fungal infections.
Concepts
The human body is quite resistant to fungi. Most serious fungal infections occur in patients with suppressed
immune defenses; for example, a patient with HIV. Community-acquired infections can affect those with intact
immune systems. Opportunistic infections are those nosocomial infections that occur in the immunosuppressed
patient. (See Table 35.1.)
LEARNING OUTCOME 3
Identify protozoan and helminthic infections that may benefit from pharmacotherapy.
Concepts
1. Protozoans are single-celled animals that cause disease in Africa, South America, and Asia. They thrive in
areas of poor sanitation, and travelers may transmit the organisms. Drugs used to treat bacterial and fungal
infections are ineffective.
2. Malaria is the most common protozoal disease and the second most fatal infectious disease in the world. It
is caused by the protozoan Plasmodium and transmitted by the bite of a female Anopheles mosquito.
Malaria requires multidrug therapy due to the complicated life cycle of the parasite. Drugs may be
administered for prophylaxis, as therapy for acute attacks, and for prevention of relapses. (See Figure 35.1
for the life cycle of Plasmodium.)
3. Goals of antimalarial therapy include prevention, treatment, and prevention of relapse. Prevention
includes the Centers for Disease Control recommendations for prophylactic antimalarials prior to, during,
and for one week after visits to infested areas. The treatment interrupts the erythrocytic stage and
eliminates the merozoites from red blood cells. Prevention of relapse involves elimination of the latent
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forms of Plasmodium residing in the liver.
4. Nonmalarial protozoan infections also thrive in unsanitary conditions. These other protozoal diseases
include amebiasis, toxoplasmosis, giardiasis, cryptosporidiosis, trichomoniasis, trypanosomiasis, and
leishmaniasis. (See Table 35.6 for a list of these infections.) Treatment of non-Plasmodium protozoan
disease requires a different set of medications from those used for malaria.
5. Helminths are parasitic worms that cause significant disease in certain regions of the world. The group
includes roundworms (nematodes), flukes (trematodes), tapeworms (cestodes), and enteriobiasis
(pinworms). Enteriobiasis is the most common helminth infection in the United States. Most helminths
enter the body through the skin or gastrointestinal tract. Pharmacotherapy for helminths is to kill the
parasites locally and disrupt their life cycles. Resistance has not yet become a problem.
LEARNING OUTCOME 4
Explain how an understanding of the Plasmodium life cycle is important to the effective
pharmacotherapy of malaria.
Concepts
Pharmacotherapy of malaria attempts to interrupt the complex life cycle of Plasmodium (see Figure 35.1). The
pharmacotherapy is aimed at prevention, treatment, and prevention of relapse. Prevention involves
administering prophylactic antimalarials prior to, during, and for one week after visits to infested areas.
Treatment involves interrupting the erythrocytic stage and eliminating the merozoites from red blood cells.
Prevention of relapse means attempting to eliminate the latent forms of Plasmodium residing in the liver.
LEARNING OUTCOME 5
Describe the nurse’s role in the pharmacologic management of fungal, protozoan, and helminth
infections.
Concepts
1. The role of the nurse in the pharmacologic management of fungal, protozoal, and helminth infections
involves careful monitoring of a patient’s condition and providing education as it relates to the prescribed
drug treatment. Obtain baseline medical, surgical, and drug history; lifestyle and dietary habits, including
use of herbal or alternative therapies; and a detailed description of symptomology and current therapies.
Obtain baseline culture and sensitivity tests prior to the beginning of therapy. Contraindicated in patients
with known hypersensitivity to the drugs.
2. Systemic antifungal therapy: This class of antifungal drugs should be used cautiously in those with renal
impairment, patients with severe bone-marrow suppression, and patients who are pregnant. Amphotericin
B (Fungizone) causes some degree of kidney damage in 80% of the patients who take it, so closely monitor
fluid and electrolyte status. Amphotericin B can cause ototoxicity: assess for hearing loss, vertigo, unsteady
gait, or tinnitus.
3. Azole therapy: Do not give ketoconazole (Nizoral) to patients with chronic alcoholism because this drug
can be toxic to the liver. Assess for nausea, vomiting, abdominal pain, or diarrhea. Also monitor for signs
and symptoms of hepatotoxicity, such as pruritus, jaundice, dark urine, and skin rash. Azoles may affect
glycemic control in diabetic patients, so monitor blood-sugar levels carefully in these patients. Monitor for
alcohol use because it increases the risk of side effects, such as nausea and vomiting, and increases blood
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pressure.
4. Superficial antifungal therapy: Assess for signs of contact dermatitis; if this is present, withhold the drug
and notify the primary health care provider. Do not use superficial antifungals, such as nystatin
(Mycostatin), intravaginally during pregnancy to treat infections caused by Gardnerella vaginalis or
Trichomonas species; use cautiously in patients who are lactating. The medications may be “swished and
swallowed” or “swished and spit” when used to treat oral candidiasis. Monitor for side effects such as
nausea, vomiting, and diarrhea when the patient is taking high doses.
5. Antiprotozoal drugs: Contraindicated in patients with hematological disorders or severe skin disorders
such as psoriasis or with patients who are pregnant. Use cautiously in patients with preexisting
cardiovascular disease and those who are lactating. Test for G6PD deficiency. Chloroquine (Aralen) may
precipitate anemia in those with G6PD deficiency and may cause bone-marrow depression. Obtain a
baseline ECG because of potential cardiac complications associated with some antimalarial drugs. Monitor
for GI side effects such as vomiting, diarrhea, and abdominal pain; oral antimalarials can be given with
food to reduce GI distress. Monitor for signs of toxicity.
6. Nonmalarial, antiprotozoal drug therapy: Antiprotozoal therapy is contraindicated in patients with
blood dyscrasias or active organic disease of the CNS and during the first month of pregnancy. These drugs
are contraindicated in alcoholics; the medication is not administered until more than 24 hours after the
patient’s last drink of alcohol. Closely monitor vital signs and thyroid function during therapy, because
serum iodine may increase and cause thyroid enlargement with iodoquinol (Yodoxin). Monitor for GI
distress; oral medications can be given with food to decrease unpleasant effects. Patients taking
metronidazole (Flagyl) may complain of dryness of the mouth and a metallic taste. Monitor for signs of
CNS toxicity, such as seizures, paresthesia, nausea, and vomiting, and for allergic responses, such as
urticaria and pruritus.
7. Antihelminthic drugs: Antihelminthic therapy should be used cautiously in patients who are pregnant or
lactating, have preexisiting liver disease, or are younger than age 2. Identification of the specific worm
must be done before treatment is initiated by analyzing samples of feces, urine, blood, sputum, or tissue.
Monitor lab results; cases of leukopenia, thrombocytopenia, and agranulocytosis have been associated with
the use of albendazole (Albenza). The patient needs to be educated on the nature of the worm infestation.
Inform the patient that some types of worms will be expelled in stool as they are eradicated. Instruct the
patient to take showers rather than baths and to change undergarment, linens, and towels daily.
LEARNING OUTCOME 6
For each of the classes shown in Drugs at a Glance, know representative examples, and explain their
mechanism of drug action, primary actions, and important adverse effects.
Concepts
1. Antifungal Drugs—Agents for Systemic Infections. Prototype drug: amphotericin B (Fungizone).
Mechanism of action: binds to ergosterol in fungal-cell membranes, causing them to become permeable or
leaky. Primary use: has a wide spectrum of activity that includes most of the fungi pathogenic to humans.
Adverse effects: fever and chills, vomiting, and headache at the beginning of therapy, which subside as
treatment continues. Phlebitis is common during IV therapy. Some degree of nephrotoxicity is observed in
most patients. Electrolyte imbalances frequently occur. Cardiac arrest, hypotension, and dysrhythmias are
possible. (See Table 35.2.)
2. Antifungal Drugs—Agents for Systemic Infections. Prototype drug: fluconazole (Diflucan). Mechanism
of action: to interfere with the synthesis of ergosterol. Primary use: to penetrate most body membranes to
reach fungal infections in the CNS, bone, eyes, urinary tract, and respiratory tract. May not be effective
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against nonalbicans Candida species. Adverse effects: nausea, vomiting, and diarrhea with high doses. (See
Table 35.3.)
3. Antifungal Drugs—Superficial Infections. Prototype drug: nystatin (Mycostatin). Mechanism of action:
binds to sterols in the fungal-cell membrane, allowing leakage of intracellular contents. Primary use:
topically used for Candida infections of the vagina, skin, and mouth. It may also be used orally to treat
candidiasis of the intestine. Adverse effects: few, other than minor skin irritation; when given orally, it may
cause nausea, vomiting, and diarrhea. (See Table 35.4.)
4. Antiprotozoal Drugs—Antimalarial Agents. Prototype drug: chloroquine (Aralen). Mechanism of
action: concentrates in the food vacuoles of Plasmodium residing in red blood cells. Once in the vacuole, it
is believed to prevent the metabolism of heme, which then builds to toxic levels within the parasite.
Primary use: it has been the prototype medication for treating malaria for over 60 years. Adverse effects:
nausea and diarrhea. At higher doses, CNS and cardiovascular toxicity may be observed. (See Table 35.5.)
5. Antiprotozoal Drugs—Nonmalarial Antiprotozoal Agents. Prototype drug: metronidazole (Flagyl).
Mechanism of action: to act as an antiprotozoal drug that also has antibiotic activity against anaerobic
bacteria. Primary use: to treat most forms of amebiasis. Adverse effects: anorexia, nausea, diarrhea,
dizziness, and headache. Dryness of the mouth and an unpleasant metallic taste may be experienced. (Table
35.7.)
6. Antihelminthic Drugs. Prototype drug: mebendazole (Vermox). Mechanism of action: to act as a broadspectrum antihelminthic drug. Primary use: in the treatment of a wide range of helminth infections.
Adverse effects: few, but as the worms die, some abdominal pain, distension, and diarrhea may be
7. Prototype Drug
 amphotericin B (Fungizone)
 fluconazole (Diflucan)
 nystatin (Mycostatin)
 chloroquine (Aralen)
 metronidazole (Flagyl)
 mebendazole (Vermox)
LEARNING OUTCOME 7
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Use the nursing process to care for patients receiving drug therapy for fungal, protozoan, and helminth
infections.
Concepts
1. Patients Receiving Amphotericin B—Assessment: Obtain a complete health history, including allergies,
drug history, allergies, and possible drug interactions. Assess signs and symptoms of current infection
noting location, characteristics, presence or absence of drainage and character of drainage, duration,
presence or absence of fever or pain. Obtain a culture and sensitivity of suspected area of infection to
determine need for therapy. Obtain baseline vital signs, especially pulse and blood pressure. Obtain renal
function including blood tests (CBC, chemistry panel, BUN, and creatinine).
2. Patients Receiving Amphotericin B—Nursing Diagnoses: Infection (current or risk for concurrent
bacterial infection); Pain, related to infection; Hyperthermia; Deficient Knowledge (drug therapy); Risk for
Injury, related to adverse drug effects; Risk for Deficient Fluid Volume, related to fever, diarrhea caused by
adverse drug effects; Risk for Decreased Cardiac Output, Ineffective Tissue Perfusion, related to adverse
effects of IV antifungals; Risk for Noncompliance, related to adverse drug effects, deficient knowledge, or
length of therapy.
3. Patients Receiving Amphotericin B—Planning: Patient will experience therapeutic effects (e.g.,
diminished signs and symptoms of infection, decreased fever); be free from or experience minimal adverse
effects. Verbalize an understanding of the drug’s use, adverse effects, and required precautions.
Demonstrate proper self-administration of the medication (e.g., dose, timing, when to notify provider).
4. Patients Receiving Amphotericin B—Implementation: Monitor vital signs frequently, especially pulse
and blood pressure, during and after infusion. Monitor kidney function. Monitor for GI distress. Monitor for
fluid overload and electrolyte imbalance, especially hypokalemia. Monitor for signs and symptoms of
toxicity and hypersensitivity. Monitor IV site frequently for any signs of extravasation or thrombophlebitis.
5. Patients Receiving Amphotericin B—Evaluation: The patient experiences therapeutic effects (e.g.,
diminished signs and symptoms of infection, decreased fever); is free from or experiences minimal adverse
effects. Verbalizes an understanding of the drug’s use, adverse effects and required precautions.
Demonstrates proper self-administration of the medication (e.g., dose, timing, when to notify provider).
6. Patients Receiving Pharmacotherapy for Superficial Fungal Infections—Assessment: Obtain a
complete health history including allergies, drug history, and possible drug interactions. Obtain a culture
and sensitivity of suspected area of infection to determine need for therapy. Obtain baseline liver-function
tests.
7. Patients Receiving Pharmacotherapy for Superficial Fungal Infections—Nursing diagnoses: Infection
(current or risk for concurrent bacterial infection); Pain, related to infection; Hyperthermia; Deficient
Knowledge (drug therapy); Risk for Injury, related to adverse drug effects; Ineffective Tissue Perfusion,
related to adverse effects of IV antifungals; Risk for Noncompliance, related to adverse drug effects,
deficient knowledge, or length of therapy.
8. Patients Receiving Pharmacotherapy for Superficial Fungal Infections—Planning: The patient will
experience therapeutic effects (e.g., diminished signs and symptoms of infection, decreased fever); be free
from or experience minimal adverse effects. Verbalize an understanding of the drug’s use, adverse effects,
and required precautions. Demonstrate proper self-administration of the medication (e.g., dose, timing,
when to notify provider).
9. Patients Receiving Pharmacotherapy for Superficial Fungal Infections—Implementation: Monitor for
possible side effects or hypersensitivity. Encourage compliance with instructions when taking oral
antifungals. Monitor topical application. Avoid occlusive dressings. Monitor for contact dermatitis with
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topical formulations. Encourage infection-control practices.
10. Patients Receiving Pharmacotherapy for Superficial Fungal Infections—Evaluation: The patient
experiences therapeutic effects (e.g., diminished signs and symptoms of infection, decreased fever); is free
from or experiences minimal adverse effects. Verbalizes an understanding of the drug’s use, adverse effects,
and required precautions. Demonstrates sproper self-administration of the medication (e.g., dose, timing,
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