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Chapter 43: Antifungal Agents
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A 43-year-old man is being treated with amphotericin B for esophageal candidiasis. Which of the following serum laboratory tests should be monitored closely?
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Answer is d. Azotemia occurs in 80% of patients who receive C-AMB for deep mycoses. Lipid formulations are less nephrotoxic. Nephrotoxicity is dose-dependent, usually transient, and increased by concurrent therapy with other nephrotoxic agents.
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A 56-year-old man with cryptococcal meningitis is being treated with flucytosine and amphotericin B. Flucytosine is metabolized to 5-flurouracil by fungal cells which inhibits DNA synthesis. The selectivity of flucytosine is due to a lack of which enzyme in mammalian cells:
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d. Uracil phosphoribosyl transferase
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e. Thymidylate synthetase
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Answer is a. The selective action of flucytosine is due to the lack of cytosine deaminase in mammalian cells, which prevents the metabolism to 5-flurouracil.
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A 48-year-old woman with a history of atrial fibrillation is being treated with warfarin. She has recently developed coccidiodal meningitis and treatment with fluconazole is started. A potential drug–drug interaction that may result in elevated plasma warfarin concentration is likely because fluconazaole inhibits
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Answer is c. Fluconazole is an inhibitor of CYP3A4, CYP2C9, and CYP2C19 (see Table 43-3). Warfarin is metabolized by CYP2C9 (see Chapter 19). The inhibition of CYP2C9 would cause an increase in warfarin plasma concentrations unless the warfarin dose is adjusted accordingly.
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