Focus on
PHARMACOLOGY
ESSENTIALS FOR HEALTH PROFESSIONALS
CHAPTER
13
Antifungal,
Antimalarial, and
Antiprotazoal
Agents
Fungal Infections
• Fungi may enter body through skin,
mucous membranes, and respiratory
tract.
• Healthy individuals are usually resistant
to most fungal infections, or mycoses.
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Fungal Infections
• Use of broad-spectrum antimicrobials,
immunosuppressive drugs for cancer
and organ transplantation, and HIV
place more patients at risk for
mycoses.
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Common Mycoses
• Candidiasis (also moniliasis or thrush)
– Yeast infection in the mouth caused by
Candida albicans
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Courtesy of Charles J. Kirkpatrick, M.D., President,
Innovative Therapeutics, Inc.
Figure 13-1
Oral Candida albicans. Courtesy of Charles J. Kirkpatrick, M.D. President,
Innovative, Therapeutics, Inc.
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Superinfections
• Usually occur in anal and genital areas
or in the vagina or mouth
• Normally, the vaginal bacteria
Doderlein bacillus controls overgrowth
of fungi.
• Penicillin therapy may destroy these
bacteria, allowing fungi to multiply
rapidly.
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Superinfections
• Ask all patients if they have a history of
allergies, such as hay fever, rashes or
asthma, or have had unusual reactions
to any drugs taken orally or by
injection.
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Thrush in Infants
• Causes difficulty in breastfeeding and
chronic diaper rash
• May infect the mother’s nipples,
causing drying or cracking
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Antifungals:
Mechanism of Action
• Most antifungal drugs interfere with
synthesis of ergosterol, a chemical in
fungal cell membranes.
– Cause change in permeability of fungal cell
membrane, slowing growth or destroying
fungal organism
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Antifungal Drugs
• Three categories of antifungal drugs:
1. Drugs for systemic mycoses
2. Oral drugs for mucocutaneous infections
3. Topical drugs for mucocutaneous
infections
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Table 13-1
Antifungal Agents
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Table 13-1 (continued) Antifungal Agents
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Systemic Antifungals
•
•
•
•
Amphotericin B (Amphocin)
Flucytosine (Ancobon)
Ketoconazole (Nizoral)
Griseofulvin (Fulvicin, Grifulvin V)
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Amphotericin B (Amphocin)
• Has widest spectrum of antifungal
activity of any systemic antifungal drug
– IV: treats systemic fungal diseases
– Topical: treats superficial moniliasis
infections
– Nasal spray: for prophylaxis of aspergillosis
in immunocompromised patients
– Oral: treats oral candidiasis
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Amphotericin B:
Adverse Effects
• Common: chills and fever, nausea and
vomiting, diarrhea, abdominal cramps,
dyspepsia, headache, vertigo,
thrombophlebitis, anemia, skin rashes
• Serious: renal damage, blood
dyscrasias, loss of hearing, cardiac
arrest
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Amphotericin B:
Contraindications
• Use cautiously in patients with impaired
renal function
• Interacts with antineoplastics, cardiac
glycosides, corticosteroids, nephrotoxic
drugs (including antibiotics and
pentamidine), thiazides, and flucytosine
(Ancobon)
• Should not be used with leukocyte
transfusions
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Amphotericin B:
Patient Information
• Teach patients to report loss of
hearing, dizziness, cloudy or pink urine,
or greatly increased urination.
• Advise patients that treatment of
cutaneous infections, such as nail
infections, usually requires several
months of therapy.
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Amphotericin B
and Kidney Damage
• Amphotericin B (Amphocin) is
nephrotoxic (damages kidneys).
• Elderly patients who have renal
impairment should be tested for
creatinine clearance.
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Interactions Between Gossypol
and Amphotericin B
• The herb gossypol, which is derived
from cottonseed oil, is sometimes used
to treat endometriosis in women.
• Use of gossypol with amphotericin B
increases the risk of nephrotoxicity.
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Flucytosine (Ancobon)
• Drug of choice to treat chromomycosis
• Second choice to treat systemic
candidiasis
• May be combined with amphotericin B
for first-choice treatment of
aspergillosis or cryptococcosis (a fungal
disease of the lungs), especially in
patients with meningitis
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Flucytosine:
Adverse Effects
• Common: nausea, vomiting, diarrhea,
skin rashes
• Serious: bone marrow suppression,
manifest by anemia, leukopenia,
thrombocytopenia
• Infrequent: sedation, confusion,
headache, hallucinations, vertigo
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Flucytosine: Contraindications
• Use with extreme caution in patients
with impaired hepatic or renal function
or bone marrow suppression.
• Interacts with amphotericin B, causing
synergistic effects and enhancing
toxicity
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Flucytosine:
Patient Teaching
• Teach patients to report fever, sore
mouth or throat, and unusual bleeding
or bruising.
• Advise patients that duration of therapy
is 4 to 6 weeks.
• Warn women to avoid breastfeeding.
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Ketoconazole (Nizoral)
• Drug of choice for treatment of
blastomycosis, coccidioidosis, and
histoplasmosis.
• Alternative drug for candidiasis
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Ketoconazole: Adverse Effects
• Common: nausea and vomiting,
diarrhea, pruritus (severe itching),
abdominal cramps, headache,
photophobia, fever, impotence
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Ketoconazole: Contraindications
• Use cautiously in patients with a history
of liver disease, alcoholism, or HIV
infection.
• Safety during pregnancy and lactation
and in children younger than 2 years
not established.
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Ketoconazole: Contraindications
• Interacts with cimetidine (Tagamet)
and rifampin (Rifadin)
• Decreases biosynthesis of androgens
and estrogens
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Ketoconazole: Patient Teaching
• Advise patients to promptly report
signs and symptoms of hepatotoxicity.
• Tell patients to avoid over-the-counter
(OTC) drugs for gastric distress (such
as Rolaids, Tums, and Alka-Seltzer).
• Tell patients to take drug as directed.
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Griseofulvin
(Fulvicin, Grifulvin V)
• Fungistatic, but not fungicidal (having a
killing action on fungi).
• Highly effective in management of
dermatophyte infections of skin, hair,
and nails.
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Griseofulvin: Adverse Effects
• Common: hypersensitivity, skin rashes,
pruritus, serum sickness, severe
headache, insomnia, fatigue, mental
confusion, psychotic symptoms,
vertigo, heartburn, nausea, vomiting,
diarrhea, flatulence, dry mouth,
unpleasant taste sensations
• Serious: nephrotoxicity and
hepatotoxicity
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Griseofulvin: Contraindications
• Do not use in patients with porphyria (a
group of diseases affecting heme, the
oxygen-binding portion of hemoglobin)
or liver disease.
• Safe use during pregnancy, lactation,
or in children younger than 2 years not
established
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Griseofulvin: Contraindications
• Interacts with alcohol, barbiturates,
oral anticoagulants, estrogen
• May decrease efficacy of oral
contraceptives
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Griseofulvin: Patient Teaching
• Teach patients to avoid exposure to
intense natural or artificial sunlight.
• Advise patients to take drug as
prescribed.
• Warn women to avoid breastfeeding.
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Malarial Infections
• A serious disease caused by a
protozoan, a single-celled highly mobile
microorganism
• Plasmodium protozoans, which cause
malaria, are transmitted to humans by
mosquitos.
• Malaria can become a long-term
condition and can kill affected persons
because of its severity.
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Table 13-2
Antimalarial Drugs
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Antimalarial Agents:
Mechanism of Action
• Interrupt different points of cycle of
parasite (an organism that lives on or
in another and from which it draws its
nourishment)
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Antimalarial Drugs
•
•
•
•
Chloroquine (Aralen)
Primaquine (Primaquine)
Quinine (Quinamm)
Hydroxychloroquine (Plaquenil)
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Chloroquine (Aralen)
• Drug of choice for oral treatment of all
malaria except that caused by resistant
P. falciparum
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Chloroquine: Adverse Effects
• Common: pigmentation of skin and nail
beds, pruritus, fatigue
• Serious: toxic psychosis, ototoxicity,
retinopathy, corneal opacities
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Chloroquine: Contraindications
• Patients with liver disease,
hypersensitivity to 4-aminoquinolines,
psoriasis, porphyria, renal disease
• Should not be used in children or in
pregnant or lactating women
• Certain antacids and laxatives decrease
chloroquine absorption.
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Chloroquine: Patient Teaching
• Tell patients to promptly report visual
or hearing disturbances, muscle
weakness, loss of balance, fever, sore
mouth or throat, unexplained fatigue,
easy bruising, or bleeding.
• Advise patients to wear dark glasses in
sunlight.
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Chloroquine: Patient Teaching
• Warn patients against driving or other
potentially hazardous activities.
• Urine may be rusty yellow or brown.
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Primaquine (Primaquine)
• Used for radical cure of relapsing vivax
or ovale malaria
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Primaquine: Adverse Effects
• Recommended doses are generally well
tolerated.
• Infrequent: nausea, vomiting,
abdominal cramps, headache
• Serious (but rare): leukopenia,
agranulocytosis, cardiac arrhythmias
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Primaquine: Contraindications
• Avoid use in patients with rheumatoid
arthritis and lupus erythematosus, and
in pregnant patients.
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Primaquine: Patient Teaching
• Instruct patients to examine urine and
report darkening or red tinge or a
decrease in urine volume.
• Advise patients to report chills, fever,
pain in the diaphragm, and cyanosis.
• Warn women to avoid breastfeeding.
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Quinine (Quinamm)
• First-line therapy for falciparum
malaria, especially severe disease
• Not used in chemoprophylaxis because
of its toxicity
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Quinine: Adverse Effects
• Common: visual and hearing
disturbances, fever, headache, flushing,
syncope (fainting), vomiting, diarrhea,
abdominal pain
• Serious: cardiovascular collapse
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Quinine: Contraindications
• Avoid in patients with visual or auditory
problems.
• Use cautiously in patients with
underlying cardiac abnormalities.
• Reduce dosage in patients with renal
insufficiency.
• Interactions: Aluminum-containing
antacids may block absorption; quinine
can raise warfarin and digoxin levels
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Quinine: Patient Teaching
• Advise patients to report faintness.
• Instruct patients to eat a balanced diet
with no excesses in fruit juices or milk.
• Warn patients to avoid OTC drugs and
to take as directed.
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Hydroxychloroquine (Plaquenil)
• Suppresses malaria attacks caused by
P. vivax, P. malariae, P. ovale, and
susceptible strains of P. falciparum
• Used adjunctively with primaquine
(Primaquine) for eradication of P. vivax
and P. malariae
• Commonly prescribed for treatment of
rheumatoid arthritis and lupus
erythematosus
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Hydroxychloroquine:
Adverse Effects
• Common: nausea, vomiting, anorexia,
diarrhea, abdominal cramps, weight
loss, fatigue, vertigo, headache,
anxiety, retinopathy, blurred vision,
mood changes
• Serious (but rare): aplastic anemia,
agranulocytosis, thrombocytopenia,
alopecia, retinopathy
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Hydroxychloroquine:
Contraindications
• Visual field changes, psoriasis,
porphyria
• Safe use for juvenile arthritis or in
lactating women not established.
• Use cautiously in patients with liver
disease, alcoholism, and impaired renal
function.
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Hydroxychloroquine:
Contraindications
• Interactions: Aluminum-and
magnesium-containing antacids and
laxatives decrease absorption
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Hydroxychloroquine:
Patient Teaching
• Instruct patients about adverse effects
and related symptoms.
• Advise patients to take as directed.
• Instruct patients to keep this drug out
of reach of children and to avoid
breastfeeding.
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Antimalarial Drugs in Children
• Children who will travel to countries
that require antimalarial vaccinations
should be vaccinated 4 to 6 weeks prior
to leaving.
• Dosages for children and infants must
be specially prepared and guidelines
followed exactly.
• Overdosage can be fatal.
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Protozoal Infections
• Entamoeba histolytica and Giardia
lamblia cause dysentery (an
inflammatory disease of the lower
intestinal tract) in humans.
• Trichomonas vaginalis (T. vaginalis)
causes a sexually transmitted disease
called trichomoniasis.
• G. lamblia causes giardiasis.
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Centers for Disease Control and Prevention (CDC)
Figure 13-2
Vaginal discharge with microorganisms due to trichomoniasis.
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Antiprotozoal Agents
•
•
•
•
•
Metronidazole (Flagyl)
Iodoquinol (Yodoxin)
Tetracyclines
Paromomycin (Humatin)
Combination therapy can eliminate
parasites from all sites
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Table 13-3
Antiprotozoal Agents
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Metronidazole (Flagyl)
• Used to treat liver abscess, intestinal
amebiasis, trichomoniasis, anaerobic
infections, vaginosis, diarrhea, colitis,
and pelvic inflammatory disease (PID)
• For prevention of postoperative
infection following colorectal surgery
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Metronidazole: Adverse Effects
• Common: nausea, vomiting, anorexia,
abdominal cramps, metallic or bitter
taste, skin rashes, pruritus, flushing,
fever, vertigo, headache, confusion,
depression, restlessness, insomnia
• Sometimes: dark-colored urine
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Metronidazole: Contraindications
• Avoid in patients with diseases of the
central nervous system.
• Withhold during pregnancy in most
cases.
• Interactions: cimetidine, disulfiram,
lithium, oral anticoagulants,
phenobarbital, alcohol, phenytoin
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Metronidazole: Patient Teaching
• Instruct patients to take as directed.
• Advise patients to refrain from
intercourse during therapy for
trichomoniasis unless a condom is used
to prevent reinfection.
• Advise patients to have sexual partners
treated concurrently.
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Iodoquinol (Diquinol, Yodoxin)
• Anti-amebicide, anti-infective,
antiprotozoal agent
• Works in intestinal lumen
• Enters cells of protozoa, affecting DNA,
inhibiting synthesis, and causing cell
death
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Iodoquinol: Adverse Effects
• Common: diarrhea, nausea, vomiting,
abdominal pain, anorexia, headache,
rash, pruritus, blurred vision, optic
atrophy, permanent loss of vision,
thyroid hypertrophy
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Iodoquinol: Contraindications
• Avoid in patients with hypersensitivity
to any iodine-containing preparations
or foods, and those with hepatic or
renal damage.
• Safe use during pregnancy or lactation
is not established.
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Iodoquinol: Patient Teaching
• Instruct patients to report skin rash,
chills, fever, weakness, or fatigue.
• Advise patients to take as directed.
• Explain to patients that their stools
need to be examined at 1, 3, and 6
months after termination of treatment.
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