Antifungal

Antifungal Drugs
Chapter 41

Mechanism of action
Drug effects
Indications

I Fungal Infections

A. Fungi: very large and diverse group of microorganisms that include all yeasts and molds.
1. yeasts:
a. single celled fungi
b. reproduce by budding.
c. also used for baking and alcoholic beverages
2. molds:
a. multicellular.
b. Characterized by long, branching filaments called hyphae.
B. fungal infections aka mycoses (mycotic infections)
1. cutaneous
2. subcutaneous
3. superficial
4. systemic
a. usually occur in an immunocomprimised host
b. can be life threatening
5. diseases
a. Candida albicans
i. due to antibiotic therapy, antineoplastics, or immunosuppressants (corticosteroids)
ii. may result in overgrowth and systemic infections
b. in the mouth
i. oral candidiasis or thrush
ii. newborn infants and immunocompromised patients
iii. contagious
c. vaginal candidiasis
i. “yeast infection”
ii. pregnancy, diabetes mellitus, oral contraceptives, antibiotics
C. some fungi are part of the normal flora of the skin, mouth, intestines, and vagina.






II Antifungal agents:
A. drugs used to treat infections caused by fungi
B. systemic work in the blood stream
C. topical work on the skin
D. broken down into major groups based on their mechanisms of action
E. Agents
1. Polyenes
a. amphotericin B
b. nystatin
2. flucytosine
3. imidazoles
a. ketoconazole
b. muconazole
c. clotrimazole
d. fluconazole
4. griseofulvin
5. allylmine
a. terbinafine

III Mechanism of Action
A. polyenes (amphotericin B and nystatin)
1. bind to sterols in cell membrane lining
2. result: fungal death
3. do not bind to human cell membranes or kill human cells
B. flucytosine
1. aka 5-fluorocytosine (antimetabolite)
2. taken up by fungal cells and interferes with DNA synthesis
3. result: fungal cell death
C. imidazoles (...azoles)
1. inhibit an enzyme, resulting in cell membrane leaking
2. lead to altered cell membrane
3. result: fungal death
D. Griseofulvin
1. disrupts cell division
2. result: inhibited fungal mitosis (reproduction)
IV Indications (systemic and topical fungal infections)
A. Choice of agent depends on type and location of infection
B. Agent of choice for the treatment of many severe systemic fungal infections is amphotericin B
V Side Effects
A. Amphotericin B “shake and bake”
1. fever
2. headache
3. chills
4. malaise
5. hypotension
6. muscle and joint pain
7. lowered potassium and magnesium levels
8. dysrhythmias
9. nausea
10. anorexia
11. main concern is renal toxicity (b/c renally eliminated)
12. neurotoxicity: seizures and paresthesias
B. fluconazole
1. nausea, vomiting, diarrhea, stomach pain
2. increased liver function studies
C. flucytosine
1. n/v, anorexia, headache, dizziness, others
D. griseofulvin
1. rash, urticaria, headache, n/v, anorexia, others
VI Nursing Implications
A. Before beginning therapy, assess for hypersensitivity, possible contraindications, and conditions that require cautious use.
B. Obtain baseline VS, CBC, liver function studies, and ECG
C. Assess for other medcations used (prescribed and OTC) in order to avoid drug interactions.
D. Follow manufacturer’s directions carefully for reconstitution and admin.
E. Monitor VS’s op patients receiving IV infusions every 15 – 30 minutes
F. During IV infusions, monitor I & O and urinalysis findings to identify adverse renal effects.
G. Amphotericin B
a. to reduce the severity of the infusion-related reactions, pretreatment with an antipyretic (acetaminophin), antihistamines, and antiemetics may be given.
b. A test dose of 1mg per 20ml 5% dextrose in water infused over 30 min should be given.
c. use iv infusion pumps and the most distal veins possible
H. Tissue extravasation of fluconazole at the iv site may lead to tissue necrosis. Monitor the iv site carefully.
I. Oral forms of griseofulvin should be given with meals to decrease GI upset.
J. Monitor carefully for side/adverse effects
K. Monitor for therapeutic effects
1. easing for the sympotoms of infection
2. improved energy levels
3. normal vital signs, including temp


Questions
Are fungal infections are difficult to treat. True
Know that oral candidiasis is contagious.
How would we prevent side effects? Tylenol, steroid, antihistamine.