3.15 Antifungals
Fungi are important to humans in a variety of ways. Both microscopic and macroscopic fungi have medical relevance, but some pathogenic species can cause mycoses (illnesses caused by fungi). See Figure 3.11[1] for a microscopic image of Candida albicans, which is the causative agent of yeast infections. Some pathogenic fungi are opportunistic, meaning that they mainly cause infections when the host’s immune defenses are compromised and do not normally cause illness in healthy individuals. Fungi are also major sources of antibiotics, such as penicillin from the fungus Penicillium.[2]
Mechanism of Action: Antifungals disrupt ergosterol biosynthesis of the cell membrane, increasing cellular permeability and causing cell death.
Indications: There are several classes of antifungals, each with their own indications:
Imidazoles include miconazole, ketoconazole, and clotrimazole, which are used to treat fungal skin infections such as tinea pedis (athlete’s foot), tinea cruris (jock itch), and tinea corporis (ringworm of the body).
Triazole drugs, including fluconazole, can be administered orally or intravenously for the treatment of several types of systemic yeast infections, including oral thrush and cryptococcal meningitis, both of which are prevalent in clients with AIDS. Triazoles also exhibit more selective toxicity, compared with the imidazoles, and are associated with fewer side effects.[3]
Allylamines, a structurally different class of synthetic antifungal drugs, are commonly used topically for the treatment of dermatophytic skin infections like athlete’s foot, ringworm, and jock itch. Oral treatment with terbinafine is also used for fingernail and toenail fungus, but it can be associated with the rare side effect of hepatotoxicity.[4]
Polyenes are a class of antifungal agents naturally produced by certain actinomycete soil bacteria and are structurally related to macrolides. Common examples include nystatin and amphotericin B. Nystatin is typically used as a topical treatment for yeast infections of the skin, mouth, and vagina, but may also be used for intestinal fungal infections. The drug amphotericin B is used for systemic fungal infections like aspergillosis, cryptococcal meningitis, histoplasmosis, blastomycosis, and candidiasis. Amphotericin B was the only antifungal drug available for several decades, but its use has associated serious side effects, including nephrotoxicity.[5]
Nursing Considerations: Administration guidelines will vary depending on the type of fungal infection being treated. It is important to monitor response of the affected area and examine class specific administration considerations to monitor client response.
Side Effects/Adverse Effects: Common side effects of antifungal medications can include skin irritations and rashes. Additional adverse effects include hepatotoxicity, nephrotoxicity, hypokalemia, and ototoxicity.
Health Teaching & Health Promotion: The client should be advised to follow dosage instructions carefully and finish the drug completely, even if they feel their symptoms have resolved. The client should report any skin rash, abdominal pain, fever, or diarrhea to the provider. The client should monitor carefully for unexplained bruising or bleeding, which may be a sign of liver dysfunction.[6]
Now let’s take a closer look at the medication grid for various antifungals in Table 3.15.[7]
Table 3.15 Antifungal Medication Grid
| Class/Subclass | Prototype/Generic | Nursing Considerations | Therapeutic Effects | Side/Adverse Effects |
|---|---|---|---|---|
| Antifungals | clotrimazole | Check for allergies
Topical cream: Apply liberally twice daily to affected area |
Improve symptoms of tinea pedis (athlete’s foot), tinea cruris (jock itch), or tinea corporis (ringworm of the body) | Topical: Skin irritation or rash |
| fluconazole | Check for allergies
Route: PO/IV Single or multiple doses Caution if liver dysfunction Potential for fetal harm |
Improve symptoms of yeast infection | Hepatotoxicity | |
| terbinafine | Cream or aerosol
Wash affected area with soap and water and allow to dry completely before applying |
Improve symptoms of tinea pedis (athlete’s foot), tinea cruris (jock itch), tinea corporis (ringworm of the body) | External use only | |
| nystatin | PO: If order is “swish and swallow,” instruct client to swish for 30 seconds or as long as tolerated before swallowing, and then do not eat or drink for 10-30 minutes afterwards
Topical cream/powder: Apply liberally twice daily |
Improve symptoms of yeast infection of skin | Powder/cream is for external use only | |
| amphotericin B | Check for allergies
Route: IV Reconstitute and dilute as directed on packaging Administer slowly over several hours initially and monitor VS every 30 minutes; may require premedication Therapy may require several months Alert: Different amphotericin B preparations aren’t interchangeable Caution if renal impairment Boxed Warning: Don’t use to treat noninvasive forms of fungal disease in clients with normal neutrophil counts |
Improvement of systemic fungal infection such as aspergillus | Monitor fluid intake and output; report change in urine appearance or volume
Monitor BUN and creatinine levels two or three times weekly. Kidney damage may be reversible if drug is stopped at first sign of renal dysfunction Hydrate client before infusion to reduce risk of nephrotoxicity Obtain liver function tests once or twice weekly Monitor CBC weekly Monitor potassium levels and report signs of hypokalemia Check calcium and magnesium levels twice weekly Drug may be ototoxic. Report evidence of hearing loss, tinnitus, vertigo, or unsteady gait |
Critical Thinking Activity 3.15
Using the above grid information, consider the following clinical scenario question:
A client in a skilled nursing facility has been receiving nystatin applied to groin folds twice daily for several weeks, but there is no sign of improvement. What is the nurse’s best response?
Note: Answers to the Critical Thinking activities can be found in the “Answer Key” section at the end of the book.
- This image is a derivative of “Candida albicans” by Dr. Gordon Roberstad, Centers of Disease Control and Prevention. https://cnx.org/contents/y54zcuVm@1/Characteristics-of-Fungi, licensed under CC0 ↵
- This work is a derivative of Microbiology by OpenStax licensed under CC BY 4.0. Access for free at https://openstax.org/books/microbiology/pages/1-introduction ↵
- This work is a derivative of Microbiology by OpenStax licensed under CC BY 4.0. Access for free at https://openstax.org/books/microbiology/pages/1-introduction ↵
- This work is a derivative of Microbiology by OpenStax licensed under CC BY 4.0. Access for free at https://openstax.org/books/microbiology/pages/1-introduction ↵
- This work is a derivative of Microbiology by OpenStax licensed under CC BY 4.0. Access for free at https://openstax.org/books/microbiology/pages/1-introduction ↵
- uCentral from Unbound Medicine. https://www.unboundmedicine.com/ucentral ↵
- This work is a derivative of DailyMed by U.S. National Library of Medicine in the Public Domain. ↵