Amphotericin B usually is administered to treat severe systemic fungal infections and meningitis caused by fungi sensitive to the drug. It’s never used for noninvasive forms of fungal disease because it’s highly toxic. It’s usually the drug of choice for severe infections caused by Candida, Paracoccidioides brasiliensis, Blastomyces dermatitidis, Coccidioides immitis, Cryptococcus neoformans, and Sporothrix schenckii. It’s also effective against Aspergillus fumigatus, Microsporum audouinii, Rhizopus, Candida glabrata, Trichophyton, and Rhodotorula.
Last-ditch effort
Because amphotericin B is highly toxic, its use is limited to the patient who has a definitive diagnosis of life-threatening infection and is under close medical supervision.
Topical concerns
Nystatin is used primarily to treat candidal skin infections. Different forms of nystatin are available for treating different types of candidal infections. Topical nystatin is used to treat candidal skin or mucous membrane infections, such as oral thrush, diaper rash, vaginal and vulvar candidiasis, and candidiasis between skin folds.
Drug interactions
Nystatin doesn’t interact significantly with other drugs, but amphotericin B may have significant interactions with many drugs.
• Because of the synergistic effects between flucytosine and amphotericin B, these two drugs commonly are combined in therapy for candidal or cryptococcal infections, especially for cryptococcal meningitis.
• The risk of kidney toxicity increases when amphotericin B is taken with aminoglycosides, cyclosporine, or acyclovir.
• Corticosteroids, extended-spectrum penicillins, and digoxin may worsen the hypokalemia (low blood potassium levels) produced by amphotericin B, possibly leading to heart problems. Moreover, the risk of digoxin toxicity is increased.
• Amphotericin B plus nondepolarizing skeletal muscle relaxants (such as pancuronium bromide) increase muscle relaxation.
• Electrolyte solutions may inactivate amphotericin B when diluted in the same solution. Amphotericin B preparations must be mixed with dextrose 5% in water; they can’t be mixed with saline solution.
• Magnesium and potassium levels and kidney function must be monitored frequently in patients receiving amphotericin.
Oral history
Oral nystatin is used to treat GI infections.
口服史
口服制霉菌素用于治疗GI感染。
Vocabulary for Today
amphotericin B – n. 两性霉素B
Candida – n. 念珠菌
Paracoccidioides brasiliensis – n. 巴西副球孢子菌
Blastomyces dermatitidis – n. 皮炎芽生菌
Coccidioides immitis – n. 粗球孢子菌
Cryptococcus neo- formans – n. 隐球菌
Sporothrix schenckii – n. 申克孢子丝菌
Aspergillus fumigatus – n. 烟曲霉菌
Microsporum audouinii – n. 奥杜盎小孢子菌
Rhizopus – n. 根霉菌属
Candida glabrata – n. 光滑念珠菌
Trichophyton – n. 发癣菌
Rhodotorula – n. 红酵母菌
flucytosine – n. 氟胞嘧啶
nondepolarizing – a. 非去极化的
pancuronium bromide – n. 泮库溴铵
Test 1. Which of the following antifungal agents is associated with bone marrow suppression and renal failure?
A. Miconazole
B. Itraconazole
C. Ketoconazole
D. Flucytosine
2. The health education nurse provides instructions to a group of clients regarding measures that will assist in preventing skin cancer. Which instructions should the nurse provide? Select all that apply.
A. Sunscreen should be applied every 8 hours.
B. Use sunscreen when participating in outdoor activities.
C. Wear a hat, opaque clothing, and sunglasses when in the sun.
D. Avoid sun exposure in the late afternoon and early evening hours.
E. Examine your body monthly for any lesions that may be suspicious.
All of the drugs are antifungal agents but only flucytosine has been associated with bone marrow suppression and synergizes with other drugs which suppress bone marrow functions. Miconazole and ketoconazole may produce hepatotoxicity, gastro-intestinal upset and headaches. Amphotericin B may produce nephrotoxicity while itraconazole is associated with gastro-intestinal upset and rare liver dysfunction.
2. B, C, E
The client should be instructed to avoid sun exposure between the hours of brightest sunlight: 10 a.m. and 4 p.m. Sunscreen, a hat, opaque clothing, and sunglasses should be worn for outdoor activities. The client should be instructed to examine the body monthly for the appearance of any cancerous or any precancerous lesions. Sunscreen should be reapplied every 2 to 3 hours and after swimming or sweating; otherwise, the duration of protection is reduced.