Ppt chapter 11

Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins

Antifungal Agents

Chapter 11


How Fungus Differs from Bacteria

• Fungus – Composed of a rigid cell wall made up of chitin and

various polysaccharides, and a cell membrane containing ergosterol.

– Protective layers of the fungal cell make the organism resistant to antibiotics.


Patients Susceptible to Fungal Infections

• Patients with AIDS and AIDS-related complex (ARC)• Patients taking immunosuppressant drugs• Patients who have undergone transplantation surgery or

cancer treatment• Members of growing elderly population no longer

protected from environmental fungi


Culture• A culture should be obtained prior to prescribing anti-

fungal agents.• Patients on antifungal agents are typically

immunosuppressed.


Amphotericin B Indications• Aspergillosis• Leishmaniasis• Cryptococcosis• Blastomycosis• Moniliasis • Coccidioidomycosis• Histoplasmosis• Mucormycosis• Candida infections (topically)


Amphotericin B• Indications - Progressive potential fatal fungal infections • Pharmacokinetics - IV form, excreted in the urine• Contraindications - Kidney disease• Adverse Reaction - Kidney failure


Systemic Antifungal Agents• Caspofungin (Cancidas) (IV)

– Approved for the treatment of invasive aspergillosis in patients who are refractory to other treatments

• Flucytosine (Ancobon) (Oral)– Less toxic drug used for the treatment of systemic

infections caused by Candida or Cryptococcus • Nystatin (Mycostatin, Nilstat) (Oral)

– Used for the treatment of intestinal candidiasis; also available in a number of topical preparations


Voriconazole and Terbinafine• Newer Agents• Voriconazole (Vfend)

– Available in oral and IV forms– Treats invasive aspergillosis and serious infections caused by

Scedosporium apiospermum, or Fuscariium species• Terbinafine (Lamisil)

– Blocks the formation of ergosterol– Inhibits a CYP2D6 enzyme system – Oral drug for the treatment of onychomycosis of the toenail or

fingernail


Azoles• Newer class of drugs used to treat systemic fungal

infections• Less toxic than amphotericin B• Less effective than amphotericin B


Question

Please answer the following statement as true or false.

Nystatin, taken orally, is used for the treatment of intestinal candidiasis.


Answer

True

Rationale: Nystatin (Mycostatin, Nilstat) (Oral) – Used for the treatment of intestinal candidiasis; also

available as a topical preparation.


Ketoconazole (Nizoral)• Used orally to treat many of the same mycoses as

amphotericin B• Works by blocking the activity of a steroid in the fungal

wall• Has side effect of blocking the activity of human steroids,

including testosterone and cortisol


Ketoconazole (Nizoral) (cont.)• Pharmacokinetics – Absorbed from the GI tract,

metabolized in the liver, excreted in the feces• Contraindications – Not drug of choice for patients with

endocrine or fertility problems• Adverse Reactions – Hepatic toxicity• Drug-Drug Interactions - Many


Fluconazole (Diflucan)• Not associated with the endocrine problems seen with

ketoconazole• Used to treat candidiasis, cryptococcal meningitis, and

other systemic fungal infections• Prophylactic agent for reducing the incidence of

candidiasis in bone marrow transplant recipients


Fluconazole (Diflucan) (cont.)• Pharmacokinetics - Available in oral and IV preparations,

excreted unchanged in the urine.• Contraindications – Renal dysfunction• Adverse Reactions – Liver or renal toxicity • Drug-Drug Interactions – Inhibits CYP450 may be

associated with drug–drug interactions


Itraconazole (Sporanox)• An oral agent used for the treatment of assorted systemic

mycoses• Associated with hepatic failure• Is slowly absorbed from the GI tract and is metabolized in

the liver by the CYP450 system• Is excreted in the urine and feces


Site of Action of Antifungals


Overall Contraindications to Systemic Antifungal Agents

• Patient’s with a known allergy• Pregnant or lactating women (with the exception of

terbinafine for life-threatening infections)• Patients with renal or liver disease

– May alter drug metabolism and excretion. Condition may worsen as a result of drug actions.


Overall Adverse Reactions to Systemic Antifungal Agents

• CNS Effects – Headache, dizziness, fever, shaking, chills

• GI Effects – Nausea, vomiting, dyspepsia, anorexia

• Hepatic Dysfunction• Dermatological Effects

– Rash and pruritus associated with local irritation• Renal Dysfunction


Question

Which of the following is considered a contraindication of Ketoconazole ?A. Patients with renal problemsB. Patients with fertility problemsC. Patients with hepatic problemsD. Patients with GI problems


Answer

B. Patients with fertility problems

Rationale: Contraindications – not drug of choice for patients with endocrine or fertility problems.


Topical Antifungal Infections• Caused by dermatophytes• Tinea Infections (Ringworm)

– Athlete’s foot (tinea pedis)– Jock itch (tinea cruris)

• Candida– Yeast infections of the mouth and vagina


Topical Antifungal Agents (cont.)

• Action/Indication– Work to alter the cell permeability of the fungus,

causing prevention of replication and fungal death – Indicated only for local treatment of mycoses,

including tinea infections• Contraindication/Cautions

– Limited to known allergy to any of these drugs


Topical Antifungal Agents (cont.)• Adverse Effects

– Local effects include irritation, burning, rash, and swelling

– When taken as a suppository or troche: nausea, vomiting, hepatic dysfunction, urinary frequency and burning, and change in sexual activity

• Drug-to-Drug Interactions– No reported drug–drug interactions


Prototype Antifungal Agent


Prototype Antifungal Agent


Prototype Antifungal Agent (Continued)


Use of Antifungals Across the Life Span


Nursing Considerations for Systemic Antifungal Agents

• Assessment: History and Physical Exam• Nursing Diagnosis• Implementation• Evaluation


Nursing Considerations for Topical Antifungal Agents

• Assessment: History and Physical Exam• Nursing Diagnosis• Implementation• Evaluation


Question

The nurse is caring for a patient with a fungal infection. Which of the following would be considered an adverse effect of an antifungal medication?A. Burning or irritation in the sexual partnerB. Abnormal kidney function testsC. Upper abdominal painD. Urinary retention


Answer

A. Burning or irritation in the sexual partner

Rationale: Adverse effects: Troche: nausea, vomiting, abnormal liver function tests; topical: stinging, redness, urticaria, edema; vaginal: lower abdominal pain, urinary frequency, burning or irritation in the sexual partner

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Ppt chapter 11

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